IntroductionA transformer is a passive electrical device that transfers electrical energy from one electrical circuit to another, or multiple circuits. Its transmission current is AC. Transformer is commonly used to increase or decrease the supply. As one of the types, high-frequency transformers use frequencies from 20 KHz to over 1MHz. This paper tells the design process of high-frequency transformers (HFTs), that is, how to calculate high frequency transformer?How to Make High Frequency Transformer?CatalogIntroductionⅠ Transformer Core1.1 Magnetic Core Material1.2 Core Structure1.3 Core Parameters1.4 Coil Parameters1.5 Coil Turns1.6 Assembly Structure1.7 Temperature Rise CheckⅡ Types of High Frequency Transformer2.1 Transformer Classifications2.2 Design RulesⅢ Transformer Core Selection CaresⅣ Main Transformer ParametersⅤ How to Calculate High Frequency Transformer?5.1 Design Principles and Methods of Transformers5.2 AP Method Analysis5.3 Parameters of Power Supply5.4 Transformer Turns CalculationⅠ Transformer CoreIn real transformers, the two coils are wound onto the same iron core. The transformer core provides a magnetic path to channel flux. The use of highly permeable material (which describes the material's ability to carry flux), as well as better core construction techniques, helps provide a desirable, low reluctance flux path and confine lines of flux to the core. The following introduces some important aspect of the transformer core.1.1 Magnetic Core MaterialWhich material is best for high frequency transformer core? Soft ferrite is widely used in switching power supply due to its own characteristics. Its advantages are high resistivity, low AC eddy current loss, low price, and easy processing into various shapes. It also has disadvantages, including low working magnetic flux density, low permeability, large magnetostriction, and relatively sensitive to temperature changes. Choosing suitable materials can fully meet the design requirements of high-frequency transformers, and they have ideal performance and price advantage.1.2 Core StructureTransformer core as a main part, the factors to be considered when selecting the magnetic core structure are: reducing magnetic leakage and leakage inductance, increasing the heat dissipation spacing of the coil, which is beneficial to shielding, easy coil winding, and convenient assembly and wiring. Magnetic leakage and leakage inductance are directly related to the core structure. If the magnetic core does not require an air gap, a closed ring-shaped or square-shaped magnetic core is better.1.3 Core ParametersIn the design of the magnetic core parameters, special attention should be paid to the magnetic flux density on working not only limited by the magnetization curve, but also by the loss, and the working mode of power transmission. When the magnetic flux changes in one direction: ΔB=Bs-Br, which is not merely limited by the saturation magnetic flux density, but also mainly by the loss, (the loss causes a temperature rise to affect the magnetic flux density). Working magnetic flux density Bm=0.6～0.7ΔB.Opening the air gap can reduce Br to increase the magnetic flux density change value ΔB. After then, the excitation current increases, but the magnetic core volume can be reduced. For magnetic flux work in two-way: ΔB=2Bm. In this case, it is also necessary to pay attention to the fact that the volt-second area of the positive and negative changes of the excitation is not equal due to various reasons, and the DC bias problem occurs. Therefore, a small air gap can be added to the magnetic core, or a DC blocking capacitor can be added in the circuit design.1.4 Coil ParametersCoil parameters include the number of turns, wire section (diameter), wire form, winding arrangement and insulation arrangement.The wire diameter is determined by the current density of the winding. Usually J is 2.5～4A/mm2. The choice of wire diameter should consider the skin effect. If necessary, make adjustments after checking the temperature rise of the transformer.1.5 Coil TurnsGenerally used winding arrangement: The primary winding is close to the magnetic core, and the secondary winding feedback winding is gradually arranged outward. Two winding arrangements are recommended as following:1) If the voltage of the primary winding is high, and the secondary winding voltage is low, the secondary winding can be used close to the magnetic core, and next is the feedback winding, and the primary winding is in the outermost, which is beneficial to the primary winding to the magnetic core. Insulation arrangement.2) To increase the coupling between the primary and secondary windings, half of the primary windings can be close to the core, then the feedback winding and secondary windings, and another half primary windings in the outermost layer, which will reduce leakage inductance helpfully.1.6 Assembly StructureThe assembly structure of a high-frequency power transformer is divided into two types: horizontal and vertical. If using plane magnetic cores, chip magnetic cores and thin film magnetic cores, they all adopt a horizontal assembly structure.1.7 Temperature Rise CheckThe temperature rise check can be carried out by calculation and sample testing. The experimental temperature rise is lower than the allowable temperature rise by more than 15 degrees, increasing the current density and reducing the wire section appropriately. If it exceeds the allowable temperature rise, appropriately reduce the current density and increase the wire section. For example, increase the heat dissipation area of the magnetic core and wire diameter.Transformer SymbolⅡ Types of High Frequency Transformer2.1 Transformer ClassificationsPower transformers are divided into three categories according to the topology:(1) Flyback transformer(2) Forward transformer(3) Push-pull transformer (in full-bridge/half-bridge)The suitable topological structure of the magnetic core structure is shown in the table on the following:Core StructureTransformer Circuit TypeFlyback TypeForward TypePush-pull TypeE cores++0Planar E Cores-+0EFD Cores-++ETD Cores0++ER Cores0++U Cores+00RM Cores0+0EP Cores-+0P Cores-+0Ring Cores-++Remarks: "+"=Appropriate   "0"=Normal   "-"=None2.2 Design Rules1) If the DC filter inductor, and the inductor core only works in one quadrant, the inductors belonging to this type include Boost inductors, Buck inductors, Buck/boost inductors, forward and push-pull transformer filtering inductors, and single-ended transformers.2) The magnetic core of the forward transformer only works in one quadrant, so the transformer needs to be magnetically reset.3) The magnetic core of the push-pull transformer is bidirectional alternating magnetization. Converters belonging to this category include push-pull converters, half-bridge and full-bridge converters, and AC filter inductors. Ⅲ Transformer Core Selection Cares1) Soft ferrite is widely used in switching power supply due to its low price, good adaptability and high frequency performance.2) Soft ferrites are common in two series: manganese-zinc ferrite and nickel-zinc ferrite. The components of manganese-zinc ferrite are Fe2O3, MnCO3, and ZnO. It is mainly used in various filters below 1MHz, inductors, transformers, etc., with a wide range of applications. The components of nickel-zinc ferrite are Fe2O3, NiO, ZnO, etc., which are mainly used for various induction windings above 1MHz, anti-interference magnetic beads, and sharing antenna matching devices.3) Manganese-zinc ferrite cores are the most widely used in switching power supplies. Depending on their use, the choice of materials is also different. The cores used in the power input filter part are mostly high-permeability, and their material grades are mostly R4K～R10K, that is, ferrite cores with a relative permeability of 4000～10000. For main transformers and output filters, most of them have high saturation magnetic flux density, and their Bs is about 0.5T (ie 5000GS). Ⅳ Main Transformer Parametersa.Transformer TopologyWith a higher saturation magnetic flux density Bs and a lower residual magnetic flux density Br,  Bs has a certain impact on the transformer and winding results. Theoretically, if Bs is high, the number of winding turns will decrease, and the copper loss will also decrease. In practical applications, there are many circuit forms of switching power supply high-frequency converters. For transformers, their working forms can be divided into two categories:BipolarThe circuit is half-bridge, full-bridge, push-pull, etc. The positive and negative half-cycle excitation currents in the transformer primary winding are identical in magnitude and opposite in direction. Therefore, the magnetic flux changes in the transformer core also move symmetrically up and down. Maximum change range of B is △B=2Bm, and the DC component in the core basically cancels out.UnipolarThe circuit is single-ended forward, single-ended flyback, etc. The primary winding of the transformer adds a unidirectional square wave pulse voltage in one cycle (single-ended flyback is the case). The transformer core is unidirectionally excited, and the magnetic flux density varies from the maximum value Bm to the residual magnetic flux density Br. At this time, △B=Bm－Br. If Br is reduced and the saturation magnetic flux density Bs is increased, △B can be increased. It can reduce the number of turns and the copper loss. b. Low Power Loss at High FrequenciesThe power loss of ferrite not only affects the output efficiency of the power supply, but also causes the core heating, waveform distortion and other undesirable consequences. The heating problem of the transformer is extremely common in practical applications. It is mainly caused by the copper loss and core loss. If Bm is selected too low when designing the transformer, and more winding turns will cause the winding to heat up, and at the same time transfer heat to the magnetic core. Conversely, if the core is the main heating body, it will also cause the winding to heat up.When selecting ferrite materials, the power loss is required to have a negative temperature coefficient relationship. If the core loss is the main body of heat, the temperature of the transformer will rise, which will cause the core loss to increase further, eventually burn out the power tube, transformer and other components. Therefore, when developing power ferrites at home and abroad, it is necessary to solve the problem of the negative temperature coefficient of the magnetic material itself. This is also a significant feature of the magnetic material for power supply. c. PermeabilityHow much is the appropriate permeability? This should be determined according to the switching frequency of the actual circuit. Generally, materials with a relative permeability of 2000 have an applicable frequency below 300kHz, and sometimes it can be higher, less than 500kHz. For materials higher than this value, a lower magnetic permeability should be selected, generally around 1300. d. Higher Curie TemperatureThe Curie temperature is the temperature at which the magnetic material loses its magnetic properties, general above 200℃. However, the actual working temperature of the transformer should not be higher than 80℃. This is because when the temperature is above 100℃, its saturation magnetic flux density Bs has dropped to 70% of that at room temperature. Therefore, an excessively high operating temperature will cause the saturation flux density of the magnetic core to drop more severely. Furthermore, when it is higher than 100°C, its power consumption has a positive temperature coefficient, which will lead to a vicious circle. For the R2KB2 material, the temperature corresponding to its allowable power consumption has reached 110°C, and the Curie temperature is as high as 240°C, which meets the requirements for high-temperature use. Ⅴ How to Calculate High Frequency Transformer?5.1 Design Principles and Methods of TransformersThere are two principle methods for designing transformers: area product AP method. AP is the product of the core cross-sectional area Ae and the coil effective window area Aw.PT-power of transformerAe- effective cross-sectional areaAw- core window areaKo-core window utilization factor, typical value is 0.4.Kf-form factor, square wave is 4, and sine wave is 4.44.Bw-the working magnetic intensity of the magnetic coreFs-switch operating frequencyKj-current density coefficient, take 395A/cm2X-core structure coefficient5.2 AP Method AnalysisAccording to the design method of power transformer, the general steps of designing transformer with area product AP method:1. Select the core material and calculate the apparent power of the transformer.2. Determine the core cross-sectional size AP, and then select the core size according to it.3. Calculate the inductance and number of turns of the primary and secondary sides.4. Calculate the length of the air gap.5. Find the wire diameter according to the current density and the effective value current of the primary and secondary sides.6. Determine whether the copper loss and iron loss meet the requirements (allowable loss and temperature rise).5.3 Parameters of Power SupplyInput voltage: 175-264VACOutput voltage: 21VOutput power: 3AThe frequency is set at 60KHz, and the duty cycle is initially set at 0.45. Using a flyback topology, choose the core material and determine the apparent power PT of the transformer.Consider the cost, choose PC40 material here:Check the PC40 data and get Bs=0.39T, Br=0.06TBm= ΔBmax*0.6=0.198T, round it to 0.2TIn order to prevent the magnetic core from being saturated momentarily, reserve a certain margin and take Bm= ΔBmax*0.6=0.198T, take 0.2T.Transformer apparent power PT, for the flyback transformer:Calculate AP:Where:J is the current density, usually taking 395A/cm2.Ku is the effective use coefficient of the copper window, which is determined according to the safety requirements and the number of output channels, generally 0.2 to 0.4. Take 0.4 here to adapt to the sudden load current. The power supply is designed in critical mode, and the critical current I0B=0.8×I0=2.4A5.4 Transformer Turns Calculation1) Minimum input voltage: Vimin=ViACmin*1.2=210V2) Turns Ration=[Vimin/(Vo+Vf)]*[Dmax/(1-Dmax)]n=[210V/(21V+1V)]*[0.45/(1-0.45)]=7.83) Secondary Side Peak Current^IsB=2*IoB/(1-Dmax)^IsB=2*2.4A/(1-0.45)=8.72A4) Secondary Side InductanceLs=(Vo+Vf)*(1-Dmax)*[1/(Fs*1000)]/^IsB*1000000Ls=(21V+1V)*(1-0.45)*[1/(60KHz*1000)]/^8.72A*1000000=23.58uH5) Primary Side InductanceLp=n*n*LsLp=7.8*7.8*23.58uH=1434uH6) Secondary Side Peak Current (continuous mode)^IsB=Io/(1-Dmax)+(^IsB/2)^IsB=3A/(1-0.45)+(8.72A/2)=9.81A7) Primary Side Peak Current (continuous mode)^Ipp=^Isp/n^Ipp=9.81A/7.8=1.257APrimary Winding and Secondary Winding Turns1) Primary Winding TurnsNp=Lp*^Ipp(^B*Ae)Np=1434uH*1.257A/(0.2*84.8)=106.28T，round it to 106T2) Secondary Winding TurnsNs=Np/nNs=106T/7.8=13.58T，round it to Ns=14T3) Feedback TurnsNv=(Vcc+Vf)/[(Vo+Vf)/Ns]Nv=(14.5V+1V)/[(21V+1V)/14T]=9.87T, round it to Nv=10TIn order to avoid saturation of the magnetic core, an appropriate air gap is added to the magnetic circuit, and the calculation is as follows:It may be necessary to correct the number of turns based on the edge effect of the air gap flux.There are two methods for the wire diameter of the primary, secondary and auxiliary windings:Bare wire areaPrimary Winding diameter: effective currentIprms=Po/^n/ViminIprms=63W/0.8/210V=0.375AWire diameter (J current density is 4A/mm2)Use two 0.18mm diameter wires and wind them together, or use AWG #28 single stranded wire.Secondary winding diameterUse 4 wires with a diameter of 0.25mm to be wound in parallel and calculate the current skin depth:The wire diameter of multiple strands must be less than or equal to dwH. For single wire winding, if the wire diameter exceeds the dwH, it is necessary to consider the use of multiple strands.The calculation of copper loss Pcu and iron loss Pfe (transformer total loss Ploss)a) Primary winding and secondary winding losses. Among them, MLT is the average turn length of the magnetic core. b) Calculate the allowable total loss Ploss and iron loss under the efficiency η.c) Find the actual loss under the operation according to the core loss curve.Iron loss per unit weight, it actually occurredThe actual iron loss should be lower than the allowable value.d) Calculate the loss per unit area Φ=Ploss/As. If the temperature rise caused by the Φ value is less than 25 degrees, the design is good.Bw Calculation:The working magnetic flux density Bw should be met the design index requirements, Bw<Bs-Br, to avoid saturation of the magnetic core. Frequently Asked Questions about High Frequency Transformer Design1. What is high frequency transformer?The primary difference is that, as their name implies, they operate at much higher frequencies — while most line voltage transformers operate at 50 or 60 Hz, high-frequency transformers use frequencies from 20 KHz to over 1MHz. ... For any given power rating, the higher the frequency, the smaller the transformer can be. 2. What are the design aspects of high frequency transformer?Design of HF transformers. High frequency transformers transfer electric power. The physical size is dependent on the power to be transfered as well as the operating frequency. The higher the frequency the smaller the physical size. 3. What is the use of high frequency transformer?These transformers are designed to handle up to 15,000 volts safely and accurately, converting high voltage and current levels between coils by magnetic induction. High Voltage, High Frequency Transformers are relied on for applications ranging from power supplies to laser equipment and particle accelerators. 4. What is difference between high frequency and low frequency?When we talk about sound, we talk in terms of high and low-frequency waves. ... This measurement of cycles per second is expressed in Hertz (Hz), with a higher Hz representing higher frequency sound. Low-frequency sounds are 500 Hz or lower while high-frequency waves are above 2000 Hz. 5. What is the frequency of transformer?What is Transformer Frequency. The three common frequencies available are 50Hz, 60Hz and 400Hz. European power is typically 50Hz while North American power is usually 60hz. The 400 Hz is reserved for high-powered applications such as aerospace and some special-purpose computer power supplies and hand-held machine tools.

IntroductionEarthing (also known as grounding) refers to the process of transferring the immediate discharge of the electrical energy directly to the earth by the help of the low resistance wire, for safety and functional purposes. Generally, the "ground" of electronic equipment has two meanings: one is to connect to the "earth". Taking the earth as the zero potential, connecting the metal shell of electronic equipment and the circuit reference point to the earth can protect the safety of equipment and personnel, such as protective earthing, lightning protection earthing, etc. In addition, the earthing in the weak current system does not necessarily mean the ground connected to the earth in the true sense. It has the effect of improving the stability of the system, shielding and protecting the electromagnetic compatibility of the system, and it can also be connected to the "earth" when necessary.What is Electrical Earthing?CatalogIntroductionⅠ Earthing Basic1.1 Electrical Earthing1.2 Earthing SymbolsⅡ What Are the Types of Earthing?Ⅲ Why Is Electrical Earthing Important?Ⅳ Earthing Q&A You Should KnowⅠ Earthing Basic1.1 Electrical EarthingAn earthing system (UK and IEC) or grounding system (US) connects specific parts of an electric power system with the ground. Earthing is a therapeutic technique that involves doing activities that “ground” or electrically connect you to the earth. In modern earthing concepts, for line engineers, the meaning of this term is usually a reference point of line voltage; for system designers, it is often a cabinet or rack; for electrical engineers, it is safe earthing or connecting to the earth. A more general definition is a low impedance path for current to return to its source. Note that the requirements are "low impedance" and "path".1.2 Earthing SymbolsPE, PGND, FG: Protective ground or chassisBGND or DC-RETURN: Power supply (battery) returnGND: Work groundDGND: Digital groundAGND: Analog groundLGND: Lightning protection groundⅡ What Are the Types of Earthing?There are many types of earthing, including single-point earthing, multi-point earthing and mixed types of earthing. Among them, single-point earthing is divided into series earthing and parallel earthing. Generally speaking, single-point earthing is used for simple circuits, such as earthing distinctions between different functional modules, and low-frequency (f<1MHz) electronic circuits. When designing high frequency (>10MHz) circuits, multi-point earthing or multilayer boards (complete ground plane) should be used. The following are four specific earthing methods.1. Earth FloatingIn electronic design, a commonly used method is floating technology. In this method, the signal ground of the circuit board is not connected to the external public ground, thereby ensuring good isolation of the circuit. The circuit is well isolated from the external ground system and is not easily affected by the interference on the external ground system. However, static electricity is easy to accumulate on the circuit and cause electrostatic interference, which may generate dangerous voltage.Small-scale low-speed (<1mhz) equipment can use earth floating, a single-point connection to the ground by the metal shell.2. Single-point earthing in SeriesThis kind of earthing method is relatively simple, and there is no need to pay so much attention to the circuit board design. So it will be used more. However, this kind of circuit will have common impedance coupling, causing each circuit module to affect each other.3. Single point earthing in ParallelThis method of earthing, although getting rid of the common impedance coupling problem of series single-point earthing, but in actual use, it will introduce too much earthing wire annoying, as to which one needs to be comprehensively evaluated in the actual process. If the circuit board area allows, use the parallel mode, and if the connection between the various circuit modules is kept simple, then use the series mode. In general, there are power modules, analog circuit modules, digital circuit modules and protection circuit modules in the downloaded board. In this case, I use a parallel single-point earthing method.4. Multi-point EarthingMulti-point earthing is used more in daily circuit design, especially in multi-module circuit design. This earthing method can effectively reduce high-frequency interference problems, but it is also prone to cause earthing loops. This point must be fully considered in the design to improve the circuit stability. The working ground of small high-speed (>10MHz) equipment should be grounded at multiple points with its metal casing. The distance between earthing points should be less than 1/20 of the wavelength of the highest operating frequency, and the metal casing should be connected to the ground at a single point.In short, in the design of electronic circuits, the most important point is to reduce the loop area of the circuit, to improve the stability of electronic design and the EMC design of electronic systems. In the actual design, have comprehensive evaluation of the above various earthing technologies to achieve the purpose of improving system stability.Ⅲ Why Is Electrical Earthing Important?As for earthing function, the introduction of earthing technology was originally a protective measure to prevent electrical or electronic equipment from being struck by lightning. The purpose was to introduce the lightning current generated to the ground through the lightning rod, thereby protecting the building. At the same time, earthing is also an effective means to protect personal safety. When the phase line touches the equipment shell caused by some reason (such as poor insulation of wires, aging of wiring, etc.), the equipment shell will have dangerous voltages. The generated fault current will flow through the neutral line to the ground, thereby playing a protective role. With the development of electronic communication and other digital fields, it is no longer sufficient to consider only lightning protection and safety in the earthing system. For example, in a communication system, the interconnection of signals between a large number of devices requires each device to have a reference ground as the signal reference ground. And with the complexity of electronic equipment, the signal frequency is getting higher and higher. Therefore, in the earthing design, special attention must be paid to electromagnetic compatibility issues such as mutual interference between signals. Otherwise, improper earthing will seriously affect the reliability of system operation. Also, the concept of "earthing" has also been introduced in the high-speed signals return technology. Ⅳ Earthing Q&A You Should KnowThe following questions relay on electrical earthing science and grounding physics to explain how electrical charges from the earth can have huge effects on our life. And how do you discharge the electrical energy directly to the earth by earthing technology. Also these Q&A give you considerable attention for the earthing system design and installation.1. What is the difference between earth earthing and electrical earthing?The earth is an object with very low resistance and very large capacitance. It has the ability to absorb infinite charge, and meanwhile can maintain the potential unchanged. Therefore, it is used as the reference potential of a system electrically, that is electrical earthing. In addition, in electronic equipment, when transmitting current and signal conversion at various levels of circuits, a reference potential is required to prevent interference from external signals. This potential is called logical ground or floating ground.2. What is the difference between the ground potential and the logical ground potential?Since the earth can absorb infinite electric charge, the potential of the earth looks macroscopically zero. Due to the influence of the natural electric field and the artificial electric field in the earth, the potential of each point of the earth is different. In engineering, 20m away from the artificial electric field is regarded as zero potential (earthing potential). The electrical ground potential is related to the current injected into the ground by the electrical system. When a large current flows into the electrical ground, the electrical ground potential may reach a very high voltage, especially when the lightning current flows into the electrical ground. The instantaneous potential of the electrical ground can reach 100,000 volts. Therefore, a separate lightning protection earthing point cannot be located in a place where have pedestrians.3. What is the shell?Due to the damage of the insulation layer of the wire, the phase wire is in contact with the outer shell of the electrical equipment, which is called a bumping shell. If the insulation of the phase wires and the enclosure of the electrical equipment does not meet the specified requirements, the equipment cannot be put into use. The reason for the insulation drop may be moisture or damage to the insulation layer, which can be analyzed according to the environment in which the circuit equipment is used.4. What is the step voltage?When an electrical device has a short-circuit fault to the ground, the fault current flows from the fault ground to the ground electrode and returns to the power source. Therefore, an electric field is generated around the ground of the fault point and the ground electrode, which is away from the ground of the fault point or the ground of the ground electrode. The closer, the higher the potential, and the farther, the lower the potential. When the distance between the two feet of a person is about 0.8 meters, standing in this electric field, because the two feet are at different potential points, there will be a potential difference. This potential difference is called the step voltage.5. What is contact voltage?When the insulation of electrical equipment is damaged and a short-circuit occurs to the shell, people who touch the electrical equipment will have the risk of electric shock. To define the degree of danger, the potential of the equipment 0.8 meters away from the horizontal direction of the electrical equipment when it fails is measured. The potential difference between the two is called the contact voltage.6. What is the earthing resistance difference between the earthing electrode and the equipment?The ratio of the earthing voltage to the earthing current is called the earthing resistance of the earthing electrode. When measuring the earthing electrode resistance in a project, an ac voltage is artificially applied to the earthing electrode, and then the current flowing into the earthing electrode is measured. The ratio of the two is the earthing resistance. The earthing resistance of the equipment is the sum of earthing wires resistances.7. What are the classifications of earthing functions?Generally divided into two categories: protective earthing and functional earthing1) Protective earthing can be divided into the following 4 types:Protective earthing: earthing the exposed conductor part of the equipment is called protective earthing. Its purpose is to prevent electrical equipment insulation damage or leakage, which may cause electric shock when people touch it.Lightning earthing: Lead lightning into the earth to prevent electric shock or other property damage.Anti-static earthing: Introduce static charges into the ground to prevent the accumulation of static electricity from causing harm to the human body and equipment.Anti-corrosion earthing: Bury a metal body underground as a sacrificial anode or cathode to protect the metal body connected to it, such as a metal oil pipeline.2) Functional earthing can be divided into the following 4 types:Working earthing: In order to ensure the operation of the power system, earthing is done at an appropriate place in the power system, which is called working earthing. In an AC system, this point is generally a neutral point.Logic earthing: To obtain a stable reference voltage, the appropriate metal parts in the electronic equipment are used as the reference zero potential, and the electronic parts that need to obtain the zero potential are connected to this metal part. This method is called logic earthing.Shield earthing: Ground the metal shell or the metal net to protect the electronic equipment in the shell or the net from external electrical interference, or prevent the electrical equipment in the shell or the net from causing interference to external electronic equipment.Signal earthing: A earthing method set to ensure that the signal has a stable reference potential.8. What is working ground?In order to ensure the safe operation of the electrical device, the earthing of any point (usually the neutral point of the power supply) of the device conductive part is called the working ground.9. What is the relationship between the safety voltage and the use environment?The safety voltage is to prevent personal electric shock. The degree of electric shock is related to the impedance of the human body, and the impedance of the human body has a great relationship with the contact condition. Under different conditions, it is different.The relationship between human body impedance and contact conditions is usually divided into three categories:1) High impedance: dry skin, dry environment, high impedance ground2) Low impedance: moist skin, humid environment, low impedance ground3) Zero impedance: for example, the human body is immersed in water10. What is the difference between short circuit and ground fault?The electrical connection between mutually insulated live conductors due to insulation damage is called a short circuit. For example, between phase wires of different phases, or between a phase wire and a neutral wire, exist an electrical connection, there may be a short circuit. The electrical connection error between the live conductor and the earth is called a ground fault. In addition, live conductors refer not only to the phase line, but also the neutral line. The ground refers to the metal shell of grounded electrical equipment, non-electrical metal pipes and the earth.11. What parts of the earthing device consist of?earthing device is a general term for earthing electrode and earthing wire.The earthing electrode is a conductor buried in the soil or concrete foundation for dissipating current. It can be divided into two types: natural earthing electrode and artificial earthing electrode.There are several types of natural earthing electrodes: the underground metal plumbing systems, the metal structure of the building and the reinforced concrete structure.The artificial earthing electrode should adopt horizontally laid round steel, flat steel, metal earthing plate, and vertically laid angle steel, steel pipe, round steel, etc.12. What are the measures to prevent direct electric shock?Insulate charged objectsUse shields or barriers to block the human body from charged objectsUse leakage switch as additional protection13. What are the measures to prevent indirect electric shock?Set up automatic power-off deviceEquipment with double insulationTake ungrounded local potential connectionElectrical isolation14. What are the types of earthing systems for high-voltage systems?1) Direct earthing, that is, the neutral point of the transformer or generator is connected to the earthing device directly or through a small resistance (such as a current transformer). This kind of earthing method has a large earthing current when a single-phase earthing short circuit occurs, so it is also called the large current earthing system.2) Ungrounded, the neutral point of the transformer in this system is not grounded or connected to earthing equipment such as arc suppression coils, large resistances, and the earthing device.15. Can the natural earthing electrode be used for the earthing of DC electrical devices?The earthing of AC electrical installations should make full use of the natural earthing electrode buried in the ground. For the earthing of DC electrical installations, it is not allowed to use the natural earthing electrode as the PE wire, earthing wire and earthing electrode of the current pattern. The earthing device is connected to the natural earthing. The distance between earthing devices and AC electrical devices shall not be less than 1m to avoid electrical corrosion.16. What is the function of total equipotential bonding?The function of total equipotential bonding (MEB) is to reduce the contact voltage of indirect contact electric shock in the building and different metal parts with different potential, which eliminate the dangerous fault voltage introduced from outside the building through electrical lines and various metal pipes.17. What is supplementary bonding?The two conductive parts are directly connected with wires to make the contact voltage of the fault drop below the contact voltage limit, which is called supplementary or additional equipotential bonding (earthing). When the earthing device fails, the indirect contact protection conditions for automatically cutting off the power supply cannot be met, supplementary bonding should be set. It should also be installed in places with special requirements such as bathrooms, hospitals, and swimming pools.18. What is local equipotential bonding?Local equipotential bonding (LEB) refers to the connection of multiple supplementary equipotential bonding through the bonding terminals in a local board, which is called local equipotential bonding.19. How to check the conductivity of equipotential bonding?1) Welding quality inspection2) Bolt connection quality inspection3) Measure resistance between branch and trunk20. What are the characteristics of arc short circuits?There are two forms of short circuit and ground fault: metallic and arc short. The current of metallic short circuit is very large, which can make the overcurrent protector (circuit breaker or fuse) act in time and the fault is not easy to go on. The short circuit point of arc short circuit has arc or electric spark and the impedance is large, therefore, the short circuit current is small. So overcurrent protection will not take effect. However, the temperature of the arc short-circuit point is very high, which can reach thousands of degrees Celsius locally. It is very easy to ignite the substances around the short-circuit point and cause a fire.Arcing short circuit not only occur in electrical and earthing faults, but poor connections between wires can also cause it. For example, cause flickering of incandescent lamps or interference for TV sets. At this time, you must check whether the connection point of the line is reliable. Frequently Asked Questions about Electrical Earthing System Basics1. What is elecrical earthing and types of earthing?Earthing is the first step towards electrical safety. ... Earthing is done to provide safety to user from electric shock. It is a set of conductors connected in series or in parallel in order to dissipate the potential difference immediately into the ground. The wire connected from equipment to earth called earthing wire. 2. What is difference between earthing and grounding?The key difference between earthing and grounding is that the term “Earthing” means that the circuit is physically connected to the ground which is Zero Volt Potential to the Ground (Earth). Whereas in “Grounding” the circuit is not physically connected to ground, but its potential is zero with respect to other points.Difference between Earthing and Grounding 3. Is grounding the same as earthing?The key difference between earthing and grounding is that the term “Earthing” means that the circuit is physically connected to the ground which is Zero Volt Potential to the Ground (Earth). Whereas in “Grounding” the circuit is not physically connected to ground, but its potential is zero with respect to other points. 4. What is the purpose of earthing?Earthing is used to protect you from an electric shock. It does this by providing a path (a protective conductor) for a fault current to flow to earth. It also causes the protective device (either a circuit-breaker or fuse) to switch off the electric current to the circuit that has the fault. 5. Which wire is used for earthing?copper wiresEarthing Lead or Earthing JointEventhough copper wires are generally used as earthing lead, copper strips are preferred for high installation as it can carry higher values of fault current due to its wider area.

"What Are Input and Output Impedance in Op-Amps?" - "1.1 Impedance Overview" -> "Understanding Impedance Basics" - "1.2 Input Impedance of Op-Amp" -> "Why Does an Op-Amp Need High Input Impedance?" - "1.3 Output Impedance of Op-Amp" -> "Why Does an Op-Amp Need Low Output Impedance?" - "1.4 Ideal Op Amp Impedance" -> "Ideal vs. Practical Op-Amp Impedance" - "Ⅱ High Input Impedance and Low Output Impedance Effect" -> "The Effects of High Input and Low Output Impedance" - "Ⅲ How to Calculate Input Impedance and Output Impedance" -> "How to Calculate Op-Amp Impedance"- Missing or improvable schema types detected: Missing Article schema, FAQPage schema.- Sections with vague/unsupported claims: "A small amount of current is decreased by any electrical input..." (Rewritten for technical accuracy: "Every electrical input sources or sinks a small amount of leakage current."); Formula for impedance was inverted (ΔI/ΔV instead of ΔV/ΔI) and has been corrected.- Estimated content freshness score: 5/10-->Summary: Operational amplifiers (op-amps) rely on extremely high input impedance to prevent signal degradation and very low output impedance to drive loads effectively. Understanding how to calculate and optimize these impedance values is critical for preventing loading effects and ensuring accurate signal amplification in modern circuit design.IntroductionThe input and output impedance of an amplifier is the ratio of voltage to current flowing in or out of these terminals. The input impedance may depend upon the source supply feeding the amplifier, while the output impedance may also vary according to the load impedance (RL) across the output terminals. Ideally, op-amps are supposed to have zero output impedance and infinite input impedance. However, practical op amp input impedance and output impedance are finite, making them critical factors in the design of any robust electronic circuit. What Are Input and Output Impedance in Op-Amps?Understanding Impedance BasicsIn electronic circuits, impedance defines the complex relationship between voltage and current. It is a combination of resistance (which is frequency-independent) and reactance (which is frequency-dependent, driven by inductors and capacitors). The input impedance of an op-amp acts as the load impedance to the preceding signal source. Conversely, the output impedance of the op-amp acts as the source impedance to the subsequent load receiving the amplified signal. Understanding these parameters is essential for proper impedance matching and signal integrity.Why Does an Op-Amp Need High Input Impedance?While the input impedance of an ideal op-amp is assumed to be infinite, practical devices always draw a microscopic amount of bias current. Every electrical input sources or sinks a small amount of leakage current, which can be modeled as a high-value resistor connected in parallel to the input terminals. Modern CMOS op-amps can achieve input impedances in the tera-ohm ($10^{12} Omega$) range, drastically reducing this current draw.Although input impedance is typically represented as a simple resistor, the input terminals also possess a tiny parasitic capacitance. At lower frequencies, this capacitance is negligible. However, at high frequencies, this parasitic capacitance provides a substantial load for AC signals, hindering rise and fall times and potentially causing severe signal distortion.Why Does an Op-Amp Need Low Output Impedance?An ideal amplifier should be capable of driving infinite current into any load without voltage loss, but practical op-amps have strict physical limitations. For instance, the widely used LM358 op-amp can typically source only 40mA and sink 20mA of current. This restriction in the output drive capability is modeled as a small internal resistor placed in series with an ideal voltage source.Because the actual output voltage is measured after this internal resistor, overloading the op-amp causes a significant voltage drop across it. Consequently, the delivered voltage falls short of the amplifier's intended output. To counter this limitation when driving heavy loads, engineers often add an external discrete output stage (like a push-pull transistor buffer) to boost current capacity.Ideal vs. Practical Op-Amp ImpedanceAn ideal op-amp features infinite input impedance and zero output impedance. Infinite input impedance ensures that absolutely no current flows into or out of the inverting and non-inverting terminals. Zero output impedance guarantees that the output voltage remains perfectly stable, regardless of the current demanded by the load.ParameterIdeal Op-AmpPractical Op-Amp (e.g., CMOS)Input ImpedanceInfinite (∞)Very High (Mega-ohms to Tera-ohms)Output ImpedanceZero (0 Ω)Very Low (10 to 100 ohms)Op Amp Impedance MatchingThe Effects of High Input and Low Output ImpedanceHigh input impedance ensures that the amplifier draws virtually no current from the preceding signal source. Because op-amps are primarily voltage-gain devices, their core task is to convert a low-energy, voltage-driven signal into a higher-voltage output without distorting the original source.Preventing the Loading Effect: If the input impedance were low, the op-amp would draw excessive current, causing a voltage drop across the source's internal resistance and degrading the signal.Maximizing Voltage Transfer: According to Ohm's Law (V=IR), a higher input impedance ensures that the maximum possible voltage drops across the amplifier's input terminals rather than being lost in the source wiring.Safe Current Management: Low impedance circuits can inadvertently trigger high current draws, which may damage sensitive sensor outputs. High input impedance safely isolates these delicate components. How to Calculate Op-Amp ImpedanceImpedance is mathematically represented by the ratio of voltage variation (ΔV) to current variation (ΔI). For an op-amp, the variation in the input common-mode voltage range is measured against the variation in the input bias current to determine dynamic input impedance.Input Impedance and Output Impedance of AmplifierUsing the voltage divider principle, you can determine the actual input and output voltages of an amplifier based on its gain, source impedance, and output impedance. The formula for the effective input voltage is:Vin = Vsource • (Zin / (Rs + Zin)) ......(1)Where Vin is the actual voltage the amplifier receives, Vsource is the original source voltage, Zin is the amplifier's input impedance, and Rs is the source's internal impedance.Similarly, you can calculate the voltage delivered to the load:Vload = Vout • (Rload / (Rload + Zout)) ......(2)Where Vload is the voltage dropped across the load, Vout is the amplifier's internal generated output voltage, Rload is the load resistance, and Zout is the amplifier's output impedance.To measure the output impedance practically, you can model it as a Thevenin equivalent circuit:Zout = Vo / Isc ......(3)Where Vo is the open-circuit output voltage, and Isc is the short-circuit output current. This formula assumes a strictly linear relationship between the output voltage and current.ConclusionOp-amps are essential in circuit designs where the input impedance must be vastly larger than the source impedance, and the effective output impedance must be infinitesimal compared to the load. The specific demands of your application will dictate the required precision of the op-amp. Ultimately, the input and output impedance of amplifiers stem from internal parasitic resistance and capacitance. By understanding these physical limits and applying the correct voltage divider formulas, engineers can design highly efficient, distortion-free amplification stages. Frequently Asked QuestionsWhat happens if an op-amp has low input impedance?If an op-amp has low input impedance, it draws excessive current from the signal source. This creates a loading effect, causing a significant voltage drop across the source's internal resistance. Consequently, the amplifier receives a degraded signal, leading to inaccurate amplification and potential signal distortion.Which type of op-amp provides the highest input impedance?Modern CMOS (Complementary Metal-Oxide-Semiconductor) and JFET operational amplifiers provide the highest input impedance. Unlike older bipolar junction transistor models like the LM741, CMOS op-amps can achieve input impedances in the tera-ohm range, drawing nearly zero bias current from the source.How does a unity-gain buffer utilize impedance matching?A unity-gain buffer leverages the op-amp's extremely high input impedance and near-zero output impedance to bridge circuits. It prevents a low-impedance load from drawing too much current from a high-impedance source, ensuring the signal voltage transfers perfectly without degradation or power loss.Can you measure op-amp output impedance directly with a multimeter?No, you cannot measure an active op-amp's output impedance directly using a standard multimeter's resistance setting. Instead, you must calculate it dynamically by measuring the open-circuit output voltage, applying a known load resistor, measuring the loaded voltage drop, and using the voltage divider formula.{ "@context": "https://schema.org", "@graph":[ { "@type": "Article", "headline": "Op Amp Input and Output Impedance Guide", "datePublished": "2021-01-23T15:45:51Z", "dateModified": "2026-03-19T15:12:00+08:00", "author": { "@type": "Organization", "name": "ApogeeWeb" }, "publisher": { "@type": "Organization", "name": "ApogeeWeb" } }, { "@type": "FAQPage", "mainEntity":[ { "@type": "Question", "name": "What happens if an op-amp has low input impedance?", "acceptedAnswer": { "@type": "Answer", "text": "If an op-amp has low input impedance, it draws excessive current from the signal source. This creates a loading effect, causing a significant voltage drop across the source's internal resistance. 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IntroductionWhat is a triac? TRIAC (Triode for Alternating Current) is an electronic component that is widely used in alternating current power control. It is a three terminal electronic component that conducts current in either direction when triggered. TRIAC is able to switch high voltages and high levels of current, and over both parts of an AC waveform. This makes triac circuits ideal for use in a variety of applications where power switching is needed. You can find its applications in switching, phase control, chopper designs, brilliance control in lamps, speed control in fans, motors etc.TRIAC Characteristics, TRIAC Structure and TRIAC WorkingCatalogIntroductionⅠ TRIAC vs Silicon Controlled Rectifiers (SCR)Ⅱ TRIAC Structure and SymbolⅢ How Do You Use a TRIACⅣ How Does a TRIAC Work?4.1 TRIAC Leakage Current4.2 SolutionsⅠ TRIAC vs Silicon Controlled Rectifiers (SCR)Thyristor also called SCR stands for silicon controlled rectifier while TRIAC stands for triode for alternating current. The TRIAC has on and off state characteristics similar to SCR. The main difference between SCR and TRIAC is that thyristor is a unidirectional device while in TRIAC as a bidirectional device. A TRIAC is defined as a three terminal AC switch which is different from the other silicon controlled rectifiers (SCR) in the sense. They can turn and regulate both parts of the AC waveform easily. This makes this component appropriate for a variety of applications where control of AC power is needed. A dimmer circuit will be an example application, and we use it domestically as a ceiling fan regulator circuit. Also it can be used to regulate a motor or electric heater's input power. This is why TRIAC is used for applications of low to medium power, leaving SCR with high-power applications. While this is a very interesting system, a problem known as "leakage current" is present. And we'll talk more about this leakage current, its adverse effects, and some well-known ways to solve these problems in this article. But let's clear out the basics of TRIAC before that. Ⅱ TRIAC Structure and SymbolAs for triac symbol, like any other electronic component, it consists of two SCRs linked in an antiparallel configuration, and if we look very closely at its symbol, it clearly reflects the TRIAC's bidirectional properties. Which you observe from the picture below.The upgraded variant of the thyristor is the TRIAC. A thyristor can only control current in one direction, as you already know, but a TRIAC can control current in both negative and positive directions. TRIAC turns in each sine wave loop because of the existence of the sine wave, which means we can use the entire cycle, unlike SCRs. Like thyristor, a TRIAC has three terminals, but it becomes a little difficult to assign names to these terminals since they are related simply to the cathode and the anode of two SCRs. Two SCRs are also connected to the gate terminal, which is why it was called Anode 1 and Anode 2 or Main Terminal 1 and Main Terminal 2 (MT1 and MT2).A multimeter can be used to test the health of a triac. First put the multimeter selector switch in a high resistance mode (100K), then connect the positive lead of multimeter to the MT1 terminal of triac and negative lead to the MT2 terminal of triac (there is no problem if you reverse the connection). Ⅲ How Do You Use a TRIACTriacs are semiconductor devices that are widely used for switching medium power AC. Let's acquire a little knowledge of  TRIAC functions before going further. As the following figure shows you.Two-thyristor AnalogyWe have previously said that as a configuration of two SCRs, a TRIAC can be realized. The above image provides a little bit more clarity on the subject, but it is much more complex to work at the semiconductor level. A TRIAC can be activated in many ways, unlike SCR, regardless of the polarity of the terminals. Regardless of the polarity of the initiating pulse, it may also be activated. When working with TRIAC, one thing to remember is that when the MT2 and gate current are at the same polarity, the sensitivity of the trigger current is much greater. We can now move on to cleaning out our key issue of leakage current with the simple cleared out.Triac Switching Circuit ExampleⅣ How Does a TRIAC Work?4.1 TRIAC Leakage CurrentThere is structural leakage current in the off state of thyristor, TRIAC, or any other solid-state AC switches, which is why a small amount of current flows through the load, this circuit is sufficient in some cases to charge a load circuit (Inductive) and causes it to flash spontaneously. We need to take careful care of the specifics and design the circuit accordingly to avoid this, and we will talk more about it in this section of this article.If the voltage of MT2 reaches a certain rated threshold voltage (which can occur due to the transient state of high voltage), the leakage current between the two terminals may enter the point at which the TRIAC breaks into conduction mode. In this state, a sudden localized heat will be produced when a sudden increase in current flows through the TRIAC, so that the TRIAC can be destroyed. Incandescent lamps are most likely the source of strong inrush currents, with capacitive loads.4.2 SolutionsBy applying one or more of the following methods, this condition can be avoided:1) Maximum Temperature Ratings Tj max. ensure that the temperature is not surpassed. As temperature rises, the current of leakage through the system increases, we can eliminate/reduce this issue by integrating specific TRIAC brands for specific requirements.2) By placing a broad value resistor from the gate to the cathode, we can reduce the TRIAC's sensitivity. This decreases the gate current, thereby reducing the current of leakage. It, on the other hand, increases the TRIAC turn-on time.3) If it is not possible to implement the methods described above, we can use a TRIAC with a less sensitive gate during the off time and apply a small degree of reverse bias to the gate. In this process, we have to minimize the dissipation of power through the gate.4) Depending on the form of load, another strategy for reducing leakage current is to fully eliminate the snubber circuit. The capacitor leakage also becomes the main source of leakage current, so we can decrease the current flow through the snubber and decrease the leakage current by removing the snubber network.If you want to know more TRIAC info, you can check its Triac I-V Characteristics curves with more examples. Before try these methods to reduce current leakage, please remember safety first! Frequently Asked Questions about TRIAC Basic and Its Applications1. What is a triac used for?The Triac is most commonly used semiconductor device for switching and power control of AC systems as the triac can be switched “ON” by either a positive or negative Gate pulse, regardless of the polarity of the AC supply at that time. 2. Which is an example of Triac?TRIAC ApplicationsTRIAC is very commonly used in places where AC power has to be controlled for example, it is used in the speed regulators of ceiling fans, AC bulb dimmer circuits etc. Let us look into a simple TRIAC switching circuit to understand how it works practically. 3. What is triac and its characteristics?A Triac is defined as a three terminal AC switch which is different from the other silicon controlled rectifiers in the sense that it can conduct in both the directions that is whether the applied gate signal is positive or negative, it will conduct. Thus, this device can be used for AC systems as a switch. 4. What is a triac switch?A Triac is a high-speed solid-state device that can switch and control AC power in both directions of a sinusoidal waveform. Being a solid state device, thyristors can be used to control lamps, motors, or heaters etc. 5. What is the working principle of Triac?The triac is another three-terminal ac switch that is triggered into conduction when a low-energy signal is applied to its gate terminal. Unlike the SCR, the triac conducts in either direction when turned on.

IntroductionIn electronics and electrical circuits, a Fuse is an electrical safety device that operates to provide overcurrent protection. In order to stop the damaging effects of overcurrent, when too much current flows through the low resistance element of the fuse, the element melts and breaks the circuit, because a special feature of the fuse is that it contains a piece of wire that melts easily. Fuses are widely used for the protection of electric motor circuits of different types. Before you read the following note, you can think about a question: what are the types of fuses and their uses?What is an Electric Fuse? and How to Prevent Short Circuit with Fuses?CatalogIntroductionⅠ Fuse Basic Overview1.1 What Are Fuses1.2 Fuse Working Principle1.3 Electrical Fuse Symbol1.4 Fuse MaterialsⅡ Electric Fuse Classification2.1 DC Fuses Basic2.2 AC Fuses BasicⅢ ConclusionⅣ Frequently Asked Questions about Fuse Types Basics and Its ApplicationsⅠ Fuse Basic Overview1.1 What Are FusesAn electrical fuse is a protection device built around a conductive strip that is designed to melt and separate in the event of excessive current. In other words, what are fuses for? The fuse breaks the circuit if a fault in an appliance causes too much current to flow. Except that, fuses are essentially temperature-sensitive devices. Even small variations from the controlled test conditions can greatly affect the predicted life of a fuse.1.2 Fuse Working PrincipleThe primary task of a fuse is to split the circuit if the circuit draws a current higher than desired, thus avoiding the harm due to short circuits.The simplest fuse type consists of a resistive part, carefully chosen for its melting point. A slight voltage drop (small enough so that the circuit downstream will not be impacted) is generated across the element when a current passes through this element, and some power is dissipated as heat. Thus, the element's temperature increases. This temperature rise is not necessary for normal currents to melt the filament. However, the melting point is easily reached if the current draw reaches the nominal current of the fuse. The resistive part melts and is disrupted by the circuit. The nominal current is determined by the thickness and length of the resistive material.To provide predictable trip currents, fuse components are made of zinc, copper, silver, aluminum, or other alloys. Over time, the element must not oxidize or corrode.1.3 Electrical Fuse SymbolWhat is the symbol of fuse? different fuse symbols in the electrical circuit diagram showed below.Electronic Symbols of Fuse1.4 Fuse MaterialsWhat are fuses made of? The material used for making fuse elements has a low melting point such as tin, lead, or zinc. A low melting point is, however, available with a high specific resistance metal shown in the table below. The material mainly used for fuse elements are tin, lead, silver, copper, zinc, aluminum, and an alloy of lead and tin. Ⅱ Electric Fuse ClassificationAfter you know what is a fuse in a circuit, the following are the types of fuse. There is a wide selection of PCB fuses in the market. Here introduce two major types: AC fuses, and DC fuses. The following note describes different types of fuses and their constriction, working characteristics.Types of Fuse Explained2.1 DC Fuses BasicCartridge FusesThis is the fused form that is the most common. In a glass envelope that is terminated by metal caps, the fuse part is encased. In a suitable holder, the fuse is mounted. As the glass envelope is transparent, whether the fuse is blown, it is easy to visually determine.This style has many versions, including the slow blow fuse and the quick blow fuse. Slow blow fuses have a larger element that can handle overcurrent and are unaffected by spikes in the appliance for a relatively short period of time. Quick blow fuses respond to existing spikes instantly.To withstand elevated temperatures, some versions of this fuse are encased in ceramic. Sand or oil is packed with fuses for high voltage applications. This is to stop arcing after it has blown between the two ends of the fuse. For direct PCB mounting, SMD variants of cartridge fuses also exist. Automotive, Blade Type & Bolted Type FusesThese fuses are designed especially for automotive systems running up to 32V and 42V at times. They come in the form of a 'sword' (a transparent plastic envelope with flat contacts) and are color-coded according to the nominal current. In other high-power circuits, some of these types are also used. Resettable Fuses/PolyfuseThese fuses are self-resetting, much as their name suggests. They contain black particles of carbon embedded inside organic polymers. The carbon black usually renders the mixture conductive. Heat, which expands the organic polymer, is created when a large current flows. The black particles of carbon are pulled apart, and conductivity decreases to the point that there is no flow of current. As temperatures decrease, conductivity is restored. The fuse does not, however, have to be replaced physically. This type of fuse is often referred to as a PTC, which means a positive temperature coefficient since the temperature rises with resistance.For computer power supplies and phone chargers, the PTC Fuse is ubiquitous. They are particularly handy here because it is difficult to replace them. They are used in aerospace devices for the same purpose.In their through-hole variants, PTCs are easily recognized by their yellow-orange colour and disc (and sometimes rectangular) form. With white markings, SMD poly fuses normally come in green or with gold markings in black. Virtually every current rating offers PTCs. Semiconductor FusesWith current flow, the power dissipated by a semiconductor increases exponentially, and semiconductors are thus used for ultrafast fuses. These fuses are commonly used to secure devices that are susceptible to even minor current spikes from semiconductor switching. Overvoltage Suppression FusesVoltage spikes may also often be dangerous to circuits, and with a fuse, an overvoltage safety system is also used to protect against both voltage and current spikes.There are NTCs (negative coefficient of temperature) put in parallel with the supply. NTC Fuses minimize resistance due to higher current flow and absorb spikes when the supply voltage spikes.Semiconductor-like devices that bidirectionally absorb voltage spikes are metal oxide varistors (MOVs). Using the linked post, you can learn more about MOV and its work.2.2 AC Fuses BasicHigh Voltage FusesIn high voltage AC transmission lines, these fuses are used where voltages can exceed several hundred kilovolts.1) HRC (High Rupture Current) FusesHRC fuses are fuses of a cartridge type consisting of a transparent steatite envelope (magnesium silicate). The fuse is packed with quartz powder that serves as an arc extinguishing agent (and, in the case of a liquid-filled HRC fuse, a non-conducting liquid like mineral oil).2) Expulsion FusesThese fuses are packed with chemicals such as boric acid, which creates heating gases. The arc is extinguished by these gases and ejected from the ends of the fuse. Copper, tin, or silver are made of fuse material. Low Voltage FusesThe low voltage fuses are divided into five types and those are rewirable, cartridge, drop out, striker, and switch fuses.1) Rewireable FusesThey are a quick fuse used in homes and offices that is reusable. A carrier and a socket are composed of them. The carrier is taken out, rewired and placed back in the socket when the fuse is blown, to restore normal service. They are slightly less effective than fuses from HRC.2) Cartridge FusesThey are very similar to DC fuses for cartridges. A transparent envelope covering the part of the fuse consists of them. It is possible to plug them in (blade type) or screw them into a fixture (bolt type).3) Drop Out FusesThey contain a spring-loaded lever arm that retracts when a fault occurs and must be rewired to restore normal service and put back in place. They are a form of fuse for expulsion.4) Striker Fuses A spring-loaded striker is provided with these fuses that can serve as a visual indication that the fuse has exploded and other switchgear is also triggered.5) Switch FusesHigh current fuses can be attached or disconnected by a handle that is manually controlled.Ⅲ ConclusionIn the field of electronics or electrical, the fuse is a small safety part in an electrical device or piece of machinery. It is considered the most crucial device which is employed in various electrical circuits. Many types of fuses with stock availability in the business can meet various circuit requirements. Ⅳ Frequently Asked Questions about Fuse Types Basics and Its Applications1. What are fuses?Fuses are sacrificial devices used to protect much more expensive electrical components from the damaging effects of overcurrent. They consist of a low-resistance metal or wire that is used to close a circuit. 2. What are the types of fuses?Different Types of Fuses – Constriction, Working & CharacteristicsDC FusesAC FusesCartridge FusesD – Type Cartridge FuseHRC (High Rupturing Capacity) Fuse or Link Type Cartridge FuseHigh Voltage FusesAutomotive, Blade Type & Bolted Type FusesSMD Fuses (Surface Mount Fuse), Chip, Radial, and Lead Fuses 3. Where are fuses used?Fuses are widely used for protection of electric motor circuits; for small overloads, the motor protection circuit will open the controlling contactor automatically, and the fuse will only operate for short circuits or extreme overload. 4. How many types of fuses are there?Fuses can be divided into two major categories, AC fuses, and DC fuses.5. What is the difference between Fuse and MCB (miniature circuit breaker)?Fuse is an electrical device that self-destructs and stops the current flow in a circuit whenever the current exceeds the predefined value. MCBs are resettable circuit protection devices that, on the occurrence of faults, stops the current flow in a circuit. 6. How do I know what fuse to use?You'll usually find the fuse rating on the side of your fuse, which will be given in amps. The fuse rating is the amount of current needed for the fuse to blow or break. When this happens, it stops the electrical power from flowing through the electrical circuit. 7. What are the different types of fuses?The fuse is the current interrupting device that breaks or opens the circuit by fusing the element and thus removes the faulty device from the main supply circuit. The fuses are mainly classified into two types, depends on the input supply voltages they are the AC fuses and the DC fuses. 8. What is the difference between AC and DC fuses?With AC circuits, the current is crossing the zero potential at 60 or 50 cycles a second. This helps in breaking the arc that forms when the fuse element melts and creates a gap. In dc circuits, the voltage does not go to a zero potential, making it more difficult to suppress the arc in the melting element's gap. 9. What is the difference between T and TL fuses?The difference between SL and TL fuses is their bases. An SL is a rejection base, while a TL is your typical edison base. The difference between S and T fuses is the same. SL and TL fuses are Loaded Link and are normally used in special, lighter applications, while S and T are used in heavier applications. 10. How do fuses protect us?The fuse breaks the circuit if a fault in an appliance causes too much current to flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit. 

Ⅰ IntroductionThe energy storage units of several devices we come across every day are batteries; they are available in various shapes, sizes, parameters, and shapes. They can usually be found in vehicles, emergency power sources, mobile devices, tablets, iPads, and many other portable electronic devices. But not all devices will use the same type of battery; each device has its own specifications and power supply requirements, and to choose the right battery for your application, you will need a battery selection guide. So, the considerations to consider when choosing a battery for your next electronic product design will be investigated in this post. If you are completely new to batteries, then it is recommended that you read this article on battery types and their applications before continuing further to understand the fundamentals of batteries selection.CatalogⅠ IntroductionⅡ Some Factors to ConsiderⅢ Rechargeable / Non-Rechargeable BatteriesⅣ Availability of SpaceⅤ System Operating VoltageⅥ Operating TemperatureⅦ Capacity-Power & EnergyⅧ ChemistryⅨ CostⅩ Shelf LifeⅪ How to Choose a BatteryⅫ FAQⅡ Some Factors to ConsiderYou must be aware of the important parameters involved in its activity when selecting a battery for your application. The truth of the battery is that, because no battery is ideal, there is no common form of battery for all applications. You should be able to manage the exhaustion of other parameters when you choose to use one parameter of the battery.  For example, if you want your battery to provide a lot of energy for your application, the internal resistance of the cell should be reduced, which can only be accomplished by increasing the surface area of the electrode. Inactive components such as current collectors and conductive aid are also improved by this because energy density is traded off to gain power. You must give up anything to get the other in a battery in order to get exactly what you want in your application. In the following picture, the important battery parameters are given.Now, to understand its significance and effect on battery efficiency during service, let's briefly look at each battery parameter.Ⅲ Rechargeable / Non-Rechargeable BatteriesIn deciding between a main and secondary battery, there might not be much uncertainty, you only have to decide whether you want the battery to be used once or several times. The primary (non-rechargeable) battery can be used for occasional applications such as toys, flashlights, smoke detectors, etc. They are also used in products such as pacemakers, wristwatches and hearing aids where charging is not feasible. The secondary (rechargeable) batteries can be used in applications where a standard power source such as cell phones, computers, cars, etc. is needed. Compared to primary batteries, secondary batteries often have a higher self-discharge rate because of their ability to recharge, which is an ignorant fact.Ⅳ Availability of SpaceThe batteries, including button cells, cylindrical cells, pouch cells and prismatic cells, are available in different shapes and sizes. In order to make your computer comfortably portable, the battery size really matters. AA, AAA and 9V batteries suitable for portable devices are the standard sizes available. In applications where there is less room but more power needed, lithium batteries (pouch type) are widely preferred. If the power demand is lower since they are very lightweight and the smallest of battery types, coin cells may also be considered.Ⅴ System Operating VoltageOne of the most significant characteristics of the battery, which is calculated based on the electrode & electrolyte used, is the battery voltage (Chemical Reaction). There is a common misconception that in any device, it is not the case that a fully discharged battery would have 0V. In fact, if the battery reads 0V, it's probably dead. A battery's output voltage should always be read from its nominal voltage level. Water is used as an electrolyte by the zinc-carbon battery and nickel-metal hydride battery and provides a nominal voltage of 1.2V to 2V, while the lithium-based batteries use organic electrolytes that can provide a nominal voltage of 3.2 to 4V. Most of the equipment's electronic parts run in the 3V voltage range. A single cell battery would be enough to power the equipment if you use a lithium-based battery. Note that the battery voltage will not be constant and will differ between the minimum value and the maximum value, depending on the battery power available. This is the minimum and maximum value shown below for each battery. Your nominal voltage would only be 3.2V to 4V if your circuit is running at 5V and you are charging it with a lithium battery. Boost converter circuits are used in these cases to convert the battery voltage required for the circuit to 5V. If your operating voltage is very high, like 24V or 12V, you can either use a 12V lead-acid battery or combine more than one lithium cell in series to increase the resulting output voltage if you need high power density.Ⅵ Operating TemperatureFor example, the battery operating with aqueous electrolytes can not be used in temperature conditions below 0 ° C as the aqueous electrolyte could be frozen below 0 ° C, in the same way,  the lithium-based batteries could work up to -40 ° C, but the efficiency could be reduced. The battery performance can be drastically modified by the temperature. The optimum charging rate for the lithium-ion batteries is between the temperature ranges of 20 ° C to 45 ° C. If you want to use a lower current/voltage outside this temperature range, this will result in a longer charge time. Lithium dendrite plating can be produced in the electrolyte if the temperature drops below 5 ° C or 10 ° C, which must be avoided by trickle charging.Ⅶ Capacity-Power & EnergyThe battery's strength determines the battery's runtime. Battery power/capacity is expressed in watt-hours (Wh). By multiplying the battery voltage (V) by the amount of current a battery can produce over a given amount of time, the watt-hour is determined. The battery voltage is almost set and the current that can be supplied by a battery is written on the battery, expressed in the Ampere-hour rating (Ah or mAh). Consider a 5V battery with a capacity of 2 amp-hours (Ah), so it has a power of 10Wh. The 2Ah battery will produce 2 Amps for 1 hour or 0.2A for 10 hours or 0.02A (20mA) for 100 hours. At a given discharge rate, temperature, and cut-off voltage, battery manufacturers often specify the power, where the capacity always depends on all three variables. A battery's capacity can tell us how much energy it can supply to an application. For instance, consider a 12V, 10Ah car battery, the battery's actual capacity is 120Wh (12V x 10Ah), but it will have a capacity of 36Wh in a 3.6V laptop battery that has the same 10Ah dissipation (3.6Vx 10Ah). You can see from the example that the amount of power a car battery can hold is three times higher than a laptop battery, even though they have the same Ah.High-power batteries always have quick discharge capabilities at high drain speeds, such as power tools or applications for vehicle starter batteries, with poor energy capacity for most high-power batteries.Ⅷ ChemistryYou would have learned by this time that all the characteristics of a battery are often dependent on the chemistry involved in the battery, so when selecting the type of battery, you should be more conscious. Batteries are known as Lead Acid Batteries, Alkaline Batteries, Ni-Cad Batteries (Nickel Cadmium), Ni- MH Batteries (Nickel Metal Hydride), Li-Ion (Lithium-Ion) and LiPoly (Lithium Polymer) Batteries based on the chemistry used in the process.Ⅸ CostThe battery will be one of the costly things in the Bill of Materials (BOM) for most portable electronic devices, so it will impact the total cost of your electronic applications most of the time. Therefore, you should know your product specifications and budget and then pick the right battery for your product.Ⅹ Shelf LifeNot all batteries are used directly after development, but they remain on the shelf for a long time before they are used. A battery's shelf life informs you how long it is possible to keep a battery unused. In primary batteries, the shelf life is largely known as a reality only because the secondary batteries can be recharged once they are used. The battery could sit idle there for years, for example, in a fire alarm siren device, until it detects a fire and activates the alarm. The battery maintains its output even if it is left unused for a long time, so care should be taken.Ⅺ How to Choose a BatteryNow that we've looked at the criteria that you should consider before selecting the battery for a portable electronic application, let's look at the common battery selection cases. Bear in mind that these are just tips and not difficult written guidelines.• You can use lead-acid batteries for items that consume more electricity, including projectors, large sound systems, and motorized projects. You can go for 'Sea deep cycle' batteries if you're going to have heavy battery use.• You can go for the lithium coin cells or small lithium polymer cells if your electronics need to be very small, about an inch on either side.• If you are going to manufacture the part, use inexpensive alkaline batteries of common sizes in large quantities. So the client considers it easy to replace them.• If you want the product to be user-serviceable, the battery can be adjusted by the customers themselves for batteries of 9V or AA capacity.• Use 3 Alkaline (4.5V) or 4NiMH (4.8V) cells if the circuit needs an input of approximately 5V.• Use a battery holder from your local shop to build a rechargeable battery pack and stick it with NiMH batteries and then begin recharging your battery.• If you want to replace any of the rechargeable batteries with your alkaline battery, test your system to make sure it will work at a lower voltage without any problems.• Always use a high-quality charger with sensors to ensure proper charging and trickle charging if you want your battery to have a longer life span since using a cheap charger would destroy your cells in the battery pack.How To Buy the Right Battery for Your CarⅫ FAQ1. How do I choose a battery?Factors to be considered while choosing a BatteryRechargeable / Non-Rechargeable batteriesAvailability of SpaceSystem Operating VoltageOperating TemperatureCapacity of the battery - Power & EnergyBattery ChemistryCost of Battery 2. What size battery does my car take?Your car's battery group size can be found in the battery section of the owner's manual. If you no longer have access to your original owner's manual, you may also consult the reference guides provided by battery retailers to determine the appropriate battery group size for your car. 3. How many Ah battery do I need for home?The battery you need will have to be powerful enough to provide the required power for at least 2 hours. As battery voltage is generally taken at 12 Volts, here is how you calculate the battery capacity. So, a battery with capacity equal to or higher than 140 Ah will suffice for your home. 4. How do I choose the right battery?To get the right battery power for your vehicle, you need to consider the cold cranking amps (CCA) and reserve capacity (RC). Cranking amps is the measure of your battery's starting power and should always match the standard requirements of your vehicle. Check the owner's manual for these specifications. 5. What brand of car battery lasts the longest?Best Rated Car Batteries for Long Lasting Performance 2020Optima RedTopExide Edge AGM Sealed BatteryOdyssey PC680ACDelco 94RAGM Professional