fuse Related Articles

Ⅰ IntroductionAs the technology evolved, several improvements from a standard fuse to the circuit breaker have also been made to the safety devices. We have been using static relays and magnetic relays for years to secure an electrical network, and now the safety systems have also changed as the microprocessors have evolved.We've heard about various kinds of relays before, and Numerical Relay was one of them, so we're going to concentrate more on this kind of relay today. The formed type of a static and electromagnetic relay is numeric relays. They are a system used in an electrical network to calculate electrical parameters and transform them into numerical data that is mathematically and logically interpreted to determine whether to activate an electrical network. A numerical relay's primary function is to protect the electrical network from unpredictable currents of failure. Due to their flexible features, numerical relays are often favored. A single numerical relay can track various parameters, such as current, voltage, frequency, time of onset, time of offset, etc. And for the analysis and control of multiple faults such as over current, over flux, different current and more, the same relay can be used.CatalogⅠ IntroductionⅡ Working and Hardware Architecture of Numerical RelayⅢ Types of Numerical Relays  3.1 Based on Logic  3.2 Based on Characteristics  3.3 Based on Actuating Parameters  3.4 Based on ApplicationⅣ ConclusionⅤ FAQⅡ Working and Hardware Architecture of Numerical RelaySince they both have identical hardware architecture with minor variations, the numeric relay can be considered a miniature device.Their architecture can seem overwhelming, but all of the architecture in these major categories can be simplified.• Input Module• CPU• Memory• Multiplexer and Analog to digital converter• Output module• Digital input/Communication module Input ModuleThe power system uses analog parameters to operate. With existing transformers and future transformers, the high-powered analog signals are stepped down. Using lowpass filters, it is fed to the numeric relay. Owing to the corona or induction effect from a nearby high voltage line, the low pass filter is used to remove the noisy signal in the device. CPUThe central processing unit (CPU) is the system's brain, which processes and filters all data protection algorithms and digital inputs. MemoryThere are two memories, RAM and ROM, in the numerical relay. Random Access Memory (RAM) is responsible for the retention and processing of input data to the relay during compilation.Read-Only Memory (ROM) is the relay's storage unit. It stores the required software and other data related to events and disturbances. The Storage Unit is a must because it allows during the occurrence of a fault to evaluate and troubleshoot any incident. Multiplexer and Analog to digital converterOnly digital data can be processed by the CPU, but the feedback from the current transformer and future transformer is analog. The Analog to Digital converter is then used to translate the signal to digital data. A multiplexer is used to select the necessary analog input for conversion if multiple analog signals need to be converted. Output ModuleThe digital contacts that are actuated when a trip command is provided by the CPU are the output module. Pulses that are produced as a response signal are these digital contacts. According to the application of the relay, the response time may be modified. Digital input/Communication moduleAs with a computer, a relay also has serial and parallel ports to link the relay to the substation's control and communication systems. To extend the tripping command, the Auxiliary relays can be attached to the digital output contacts.Ⅲ Types of Numerical RelaysFor different types of safety, numerical relays are used and are graded based on characteristics, logic, parameters of action and application. Although they are categorized under different circumstances, their function remains the same, in the event of a fault in the electrical network, to enable the travel system.3.1 Based on LogicSuch classifications are made based on the relay's logical operation.• Over Current/ Earth Fault: It will cause the circuit breaker when excessive current flows through a device. Used for protection against transformers and feeders.• Directional overcurrent: When the fault forces the power to flow in a specific direction, it is controlled (Opposite to the specified direction). Used for the safety of transformers, generators, and bus bars.• Differential:  When the phase difference of two or more equivalent electric quantities exceeds the stated value, the differential relay is set to trip. It can protect transformers from localized faults and generators.• Under/ Over Voltage: Under such conditions, the voltage in an electric network may drop or rise below or above a fixed value, the circuit is tripped.• Distance: The function of this type of relay is dependent on the distance between the fault impedance and the location of the relay. They are primarily used to safeguard transmission lines.3.2 Based On CharacteristicsThese classifications are based on their tripping property• Instantaneous relay: If the trigger is triggered directly after a fault occurs, no time delay will occur.• Definite Time Relay: Only activated if the fault stays in place after a certain time.• Definite Minimum Time (IDMT) Inverse Time Relays: These relays are often used on transmission lines. When the line current is higher than the safe value, the circuit breaker is triggered.• Voltage restraint over current relay: The relay is only triggered if the conditions of both under-voltage and over-current arise at the same time.3.3 Based on Actuating Parameters• Current relays• Voltage relays• Frequency relays• Power relays Etc.3.4 Based on Application• Primary relay• Backup relayThe entire network could crash if the security system fails, so they use the backup relay. And if the primary relay goes wrong, doing this would help us secure the machine.Ⅳ ConclusionNumeric relays are often used for automatic safety in the generating stations and substations. Different components such as feeder, engine, generator, transmission line, transformers and bus bars can be secured by such relays. Relays are available from different firms, such as Siemens, ABB, Schnieder Electric, Alstom, Texas, etc. Each business has its own software that can help us communicate with their relays and program the security algorithm. You can construct your own algorithm for security and feed it to the relay once you know about the parameter and the various types of faults that could occur in a power system. It doesn't take years of training and practice to become an expert in the defense of the power system to become one overnight. To become an expert, keep learning and keep on investigating.Ⅴ FAQ1. What is numerical protection relay?Numerical relay is the relay in which the measured AC quantities are sequentially sampled and converted into numerical data that is mathematically and/or logically processed to make trip decisions. Numerical relay is actually the digital relay as a unit for which manufacturers has developed standardized hardware, which can be used in conjunction with suitably developed software to meet variety of production requirements and applications. 2. What is the difference between a relay and a fuse and a circuit breaker?A relay is a control component used for signalling or switching according to control voltage applied to it’s terminals. A fuse is a protective device to limit the let through energy based on the current limit being exceeded. These are used once & then disposed of (not re-usable.) The fuses can be selected according to application & rated current (IE a motor, transformer or capacitor protection device) A circuit breaker (CB) is also a protection device used to limit let through energy on a fault, also with different thermal characteristics according to application & some LV units with a variable current threshold & tripping curve. A CB has limits - IE on LV systems, some are rated say 35kA, other larger units 60 or 80kA according to the system & calculated worst case fault current. 3. What is meant by numerical relay?In utility and industrial electric power transmission and distribution systems, a numerical relay is a computer-based system with software-based protection algorithms for the detection of electrical faults. Such relays are also termed microprocessor-type protective relays. 4. What is numerical overcurrent relay?A 'Numerical over Current Relay' is a type of protective relay which operates when the load current exceeds a preset value. ... The overcurrent relay of IDMT is the relay that starts to operate after the intended time delay. The time delay is also known as operation time. 5. What are the advantages of numerical relay?• Compact Size. • Flexibility. • Reliability. • Multi-Function Capability. • Different types of relay characteristics. • Digital communication capabilities. • Modular frame.• Low burden. 6. Which transistor is used in the numerical relay?The high-powered analog signals are stepped down with the current transformer and Potential transformer. It is fed to the numeric relay using a lowpass filter. The low pass filter is used to eliminate the noisy signal in the system due to the corona or induction effect from a nearby high voltage line. 7. What is the difference between numerical relay and static relay?A big difference between conventional electromechanical and static relays is how the relays are wired. ... Electromechanical and static relays have fixed wiring and the setting is manual. Numeric relays, on the other hand, are programmable relays where the characteristics and behavior can be programmed. 8. How does a numerical relay work?Numerical relays use a specialized digital signal processor (DSP) as the computational hardware, along with associated software tools. The relaying voltage and currents are passed through an isolation transformer. 9. What do you mean by a numerical protection scheme?Numerical protection relays are digital systems in constant communication with substation automation systems through menu-driven interfaces. They have configurable binary inputs, outputs, and programmable logic. They monitor, measure, and record electrical values, faults and disturbances, and events. 10. What are the demerits of numerical relay?1 relay can perform only 1 function. There are some disadvantages of the microprocessor are given below, The microprocessor has a limitation on the size of data. Wide Range of setting, more accurate, Low burden hence low VA of CT is required which minimizes the cost. 

I Introduction What is a blown fuse? A fuse is an electrical safety device that operates to provide over-current protection of an electrical circuit. Its essential component is a galvanized wire with antimony tin alloy that blows (melts) when too much current flows through it, thereby interrupting the current. This process of self-protection is called a blown fuse. This passage introduces blown fuse in the household circuit and car, mainly including its working principle, causes of a blown fuse, and how to repair it.  CatalogI IntroductionII Blown Fuse in Household Circuit2.1 Blown fuse in Household Circuit2.2 Slow Blow Fuse VS. Fast Blow FuseIII Help3.1 Six Reasons Why Fuses Blow3.2 Causes of Circuit fault From the Perspective of Blown fuse3.3 How to Change Household Fuse?IV Blown Fuse In Car4.1 What Is A Blown Fuse In Car?4.2 Why does a Car Fuse Blow?4.3 What are the Symptoms of a Blown Car Fuse?4.4 How to Replace a Fuse in a CarV One Question Related to Resistor Classification5.1 Question5.2 AnswerVI FAQII Blown Fuse in Household Circuit2.1 Blown Fuse in Household CircuitWith the increase of fire and electricity consumption in modern households, the frequency of household fires is getting higher and higher, which has become a focus of public attention. And a considerable part of the fire is caused by the blown fuse. In the state of high voltage and large current, the fluctuation and surge of the grid voltage will cause the current in the power supply to increase instantaneously and cause the fuse to blow.Figure 1. Fuse Figure 2. Blown Fuse2.2 Slow Blow Fuse VS. Fast Blow FuseLiterally, the difference between a slow blow fuse and a fast blow fuse is reaction speed. One reaction is faster and one reaction is slower. From a technical perspective, slow blow fuses are more resistant to surges than fast-blow fuses. In other words, slow-blow fuses have a higher ability to withstand instantaneous pulse currents than fast-blow wires. They can resist the surge of the surge current brought by the switch and do not act, thus ensuring the normal operation of the device. Therefore, a slow blow fuse is also called a surge resistance fuse. To explain from a deeper level, a slow blow fuse has a relatively large melting heat value I2t, and the energy required when the fuse blows are relatively large. So for fuses of the same rated current, slow blow fuses are much more pulse-resistant than fast-blow fuses. Because the I2t of the slow blow fuse is larger than that of the fast blow fuse of the same specification when the total current of the circuit is too large and the fuse blows, the slow blow will be slower than the fast blow fuse. But it doesn’t mean slow blow fuse is worse than fast blow fuse. Because if there is a fault in the circuit, the over-current will not disappear automatically, and the energy of the continuous over-current will greatly exceed the I2t of the fuse. No matter what kind of fuse, it still will be blown. Therefore, the time difference between fast-blow fuses and slow blow fuses is not so important for the device requirements they protect. Only in the case of sensitive devices in the protected circuit that require special protection, the performance of the slow blow fuse will be affected. Therefore，two kinds of blow fuse will be used in different circuits. For example, a purely resistive circuit, or a circuit that needs to protect some more sensitive and expensive components, the fast-blow fuse is necessary. On the contrary, it is best to use slow blow fuses in the power input/output parts of some circuits. In addition to protecting IC circuits, slow blow fuses can be used in most cases where fast-blow fuses are used to improve pulse resistance; on the contrary, if fast-blow fuses are used in places where slow blow fuses are used, it will often cause the power to be turned off immediately. The fuse cannot work normally.III Help3.1 Six Reasons Why Fuses Blow(1) Overloaded CircuitToo many appliances are operating at the same time,  resulting in household electricity overload, so that the fuse is blown. This situation is especially likely to occur when using air conditioners, electric heaters or adding other larger power appliances. Solution: Cut back on all that power that’s tapping a single circuit. Find outlets on other circuits to plug into or unplug what you aren’t using. (2) Connection ProblemsIn some families, although the fuse selection is reasonable and the load is not too large, it still occurs blown fuse as soon as it uses larger power appliances such as air conditioners, electric heaters, and rice cookers. The reason may be that when the fuse is installed or replaced, the fuse and the screw are in poor contact, causing fire and heating, and the screws fixing the fuse are oxidized and burned out. (3) Short CircuitIf the fuse is replaced but still blows as soon as you closed the switch, there may be a short circuit. May be short circuit or load short-circuit. Electric kettles, rice cookers and other commonly used high-power electrical appliances and inferior electrical appliances are prone to short-circuit failure. Solution: Make sure the faulty device is unplugged and there is no damage to the outlet. First, test the circuit. Then check for any damage on or around the electrical panel. If you see any damage, call an electrician before doing anything else with it. If there is none, flip the breaker switch back to its operating position. If it trips again, though, call an electrician. (4) Ground FaultA particular type of short circuit, a "ground-fault," occurs if a hot wire comes in contact with a ground wire or a metal wall box or touches wood framing members. Ground faults can be especially dangerous when they occur in areas with high levels of moisture, such as kitchens or bathrooms, or outdoor locations. (5) PulseWhen the circuit is started or the power supply is unstable, an instantaneous large current causes the fuse to be disconnected. Also, the screw is not tightened when the fuse is installed, or the fuse is damaged, all will cause the fuse blown. (6) The Wrong Type of Fuse Was InstalledFuses come in many shapes, sizes, and configurations. Many look similar but actually have very different functions. A suitable fuse must be selected and used. The fusing current of the fuse is usually 1.5-2.0 times the rated current. For example, when the total power of all appliances in the household is more than 1100W, choose a 5 amp fuse, and use a number 20 fuse with a diameter of 0.98MM. When the current exceeds 7.5 amps to 10 amps, the fuse will automatically blow to achieve the purpose of protection. 3.2 Causes of Circuit fault From the Perspective of Blown FuseThe blown fuse is one of the common faults of the circuit. If not handled properly, it will cause a new fault. Therefore, we should learn to judge the cause of circuit failure from the fuse blown condition. (1)Situation: The fuse blows fast, often with a "snap" sound. Most fuses are turned into small round beads. The gap between the fuses is large, and sometimes the entire fuse is almost completely melted.Analysis: This situation indicates that the blown fuse is caused by a short circuit in the line. Therefore, the circuit can work normally only after finding the short-circuit place, eliminating the short-circuit fault, and then connecting the fuse. (2)Situation: The fuse is disconnected from the middle, the gap between the disconnection is small, and a very thin residual part is left at both ends.Analysis: This is caused by the fuse being too thin, or the passing current is too large. It should be installed with a slightly thicker fuse. (3)Situation: The connection between fuse and screw joints is blown out, and the disconnection gap is small.Analysis: This is because the fastening screw that fixes the fuse is not tightened, the fuse is not in good contact with the screw, the resistance is too large when the current passes, and the generated heat is also increased. Heat doesn't dissipate as fast as it produces, so the fuse blows. In this case, connect the fuse directly and tighten the fastening screws. (4)Situation: The fuse blowing position is uncertain and the gap is small.Analysis: This situation is generally caused by the longitudinal tension of the fuse or a gap in the radial position, and the local diameter of the fuse becomes thinner. Just replace it with a new one. 3.3 How to Change Household Fuse?• Guide(1) The fuse of Knife Switch① Find the main knife switch of the circuit and check the power supply to make sure that the fuse in the knife switch has blown.② Put on rubber shoes and rubber gloves. Bring the prepared pliers and spare fuse in advance.③ After power off, disassemble the upper and lower body shells of the knife switch and use the pliers to remove the old fuse that has melted. Be careful not to touch the electrical circuit.④ Replace with a new fuse and then check if there is a short circuit. If not, you can install the case and close it. (2) Household fuse① Open the fuse box with a screwdriver and then check to see if the fuse is blown.② Install a fuse of similar length to the previous fuse. After installation, check whether it is done. How to Replace Fuse Wire of a Blown Fuse• AttentionWhen replacing the fuse, please pay attention: remove the cover of the insulation box, and do not directly connect the fuse in the insulation box. When installing the fuse, the two ends of the fuse should be wound clockwise around the screw. It should not be over-tightened or loosened, so as not to damage the fuse or cause poor contact, otherwise, it will be easy to blow.IV Blown Fuse In Car4.1 What Is A Blown Fuse In Car?Just like many other appliances, the purpose of fuses in cars is to protect the electrical system within. The basic components of a fuse are one fuse element and two terminals. And the fuse itself works as a bridge between the vehicle and the particular system. If the system is overheated, the fuse element will heat up and melt, and, eventually, the circuit will stop working.4.2 Why does a Car Fuse Blow?The circuit of a general vehicle has gone through a very detailed experiment before leaving the factory, even at the beginning of the design. It should be fine, but why does the vehicle fuse still break? Normally, there are two main reasons for the breakdown of a car fuse, one is that the load of the electrical appliance is too large, and the other is the short circuit in the car circuit. The electrical appliance is overloaded. This is also the reason why most fuses blow.  After buying a car, some people randomly modify electrical equipment, changing headlights, car audio equipment, using inferior cigarette lighters, adapters, and high-power electrical appliances. The operating power of some electrical equipment may be higher than the factory-set value. Once used, it may cause the fuse of the lamp to blow and short circuit in the automobile circuit. After the car has been used for a long time, some of the wire rubber has deteriorated, which has exposed the metal wire and caused a short circuit. Some car owners will directly flush the engine compartment with water pipes, which may cause water in the fuse box and short circuit.4.3 What are the Symptoms of a Blown Car Fuse?After the car fuse is blown, the most intuitive performance is that the car's related functions are disabled and the car cannot drive normally. The battery has power but the vehicle cannot start. In this case, it is likely that the fuse responsible for starting the motor has burned out. When you find that the vehicle can not start, remember not to start continuously, which will cause the battery to discharge continuously and lead to complete power failure. While the vehicle is running, the tachometer display is normal, but the speedometer display is zero, and the ABS warning light is on, indicating that the fuse corresponding to the ABS is burned out.4.4 How to Replace a Fuse in a Car(1) Turn off the start switch and all electrical equipment(2) Disconnect the negative battery cable(3) Figure out the blown fuse.(4) Using needle-nose pliers or some small tweezers, remove the broken fuse.(5) Replace the blown fuse with another new fuse of the same amperage.If the replacement fuse is damaged, you should immediately go to the relevant car service station for inspection. How To Safely Change A Blown FuseV One Question Related to Blown Fuse5.1 QuestionHow does blown fuse work?A. By having pieces of metal wire that melt when current gets too highB. By having an electromagnet that will break a circuit if the current gets too highC. By having pieces of metal wire that melt when current gets too lowD. By having an electromagnet that will break a circuit if the current gets too low5.2 AnswerA  VI FAQ1. How do I know if a fuse has blown?Remove the fuse from its holder. In some cases, you may need a small screwdriver to unscrew the fuse holder cap. Look at the fuse wire. If there is a visible gap in the wire or a dark or metallic smear inside the glass then the fuse is blown and needs to be replaced. 2. What happens when a fuse blows?When a fuse blows, a metal filament inside the fuse has burned through, meaning that you'll need to replace the fuse with a new one. 3. How long do fuses last?Fuses never need to be replaced unless they are tripped/activated by a failing component or any other even with the circuits of the car. They are encapsulated in plastic and are in a vacuum inside the piece. As long as the current limit isn't reached, that wire will not burn out. 4. Can a blown fuse stop a car from starting?A blown fuse in the starter circuit could be the cause of a no-start problem. Broken or corroded wiring-Damaged or dirty wires to the battery or to the starter solenoid (or wires that are loose) can prevent sufficient power from reaching the starter. 5. Can a blown fuse cause a fire?Absolutely, an outlet that has blown a fuse can start a fire. If the problem was whatever was plugged into it, and that item is no longer there, there should be no problem, but if the problem was within the outlet itself it should be repaired immediately. The time to a fire could be from 2 minutes to 2 years. 6. Do fuses go bad with age?Yes indeed, fuses do expire from old age. Yes, fuses can get tired, but it's equally possible you have an intermittent problem with the switch or perhaps the starting capacitor (assuming it's not 3ph). First, replace the fuse and see if you get lucky, then diagnose further if needed. 7. What causes a fuse to burn?First, and most commonly, when too many lights or plug-in appliances draw power from the circuit, it can overload the capacity of the fuse and cause the metal ribbon inside the fuse to melt through. ... A mis-wired lamp, for example, can cause a short circuit and blown fuse if it is plugged into an outlet. 8. How do you fix a blown fuse in a plug?Lift it with your screwdriver to dislodge it. Replace the fuse with a fuse of the same amperage (check the appliance's instructions if unsure) Reassemble the plug, plug it into the wall and switch the device back on. If a blown fuse was the problem, your appliance should now be working again as normal. 9. How does a fuse in a plug work?A plug fuse is a safety device that is connected to an electrical circuit to prevent excessive current flow during fault conditions. Upon overload, the wire fuse element heats up and melts, or blows with a resounding bang, interrupting and cutting off the current flow. 10. Can a fuse look good and still be bad?Due to the way fuses are engineered, the likelihood that a fuse would become faulty without blowing is pretty slim, but there are rare instances in which a fuse might appear completely fine, even though no current runs through it.