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  This article will be divided into three parts--individual transformer , parallel transformer and redundancy requirements for bulk power transformers.     Catalog   I. Individual Transformer II. Parallel Transformer III. Redundancy Requirements for Bulk Power Transformers FAQ   I. Individual Transformer   Just see the following picture, it includes the protection for banks where fuses are used on the primary. Overall differential protection may be applied by using CTs in the transformer primary bushings for larger or important banks. The common connection is shown with delta on the source (primary) side and wye-grounded on the secondary side. Other possible connections: delta–delta, wye–wye, or primary-wye– secondary-delta. Figure 1 – Transformer protection without primary-side circuit breaker   About the analysis of power circuit, you can see the article: Analysis of Switching Power Supply Principle   Note: Secondary circuits should have 51 and 51N relays. Therefore, transformer secondary breaker and relays may be omitted unless another source connects to the secondary bus. 51N relay can be omitted with 51G available.   For transformer banks with primary breakers, the protection is summarized in Figure 2.   Relay 51G provides backup protection for secondary bus and feeder faults and must be time-coordinated, with other ground relays protecting the various feeder circuits on the secondary bus. Similarly, phase relays 51 must be coordinated with the phase relays on the feeders. The common connection is shown with delta on the source (primary) side and wye-grounded on the secondary side. Other possible connections: delta–delta, wye–wye, primary-wye– secondary-delta, three-winding, or autotransformer.   Figure 2 – Transformer protection with primary-side circuit breaker   "52S may be omitted in some applications requiring 151G to coordinate with and trip the secondary circuit devices if used." II. Parallel Transformer   The protection for transformer banks where the secondaries are connected together by a bus tie breaker is summarized in the following picture(a,b,c).   The arrangement shown is typical for large- or critical-load substations, especially for industrial plants. The loads are supplied from separate buses that are connected together by a bus tiebreaker (52T) that may be operated either normally closed (NC) or normally open (NO).   Figure 3a – Single line diagram of transformer and secondary bus protection for a typical double-source supply with secondary tie and breaker   If you operated NO, the protection of the first picture and second is applicable. If operated with 52T NC, the protection of the first picture and second is applicable with the secondary side modified. Figure 3b – Secondary protection with high-side fuses With the bus tiebreaker closed, there is a possibility for the interchange of power between the two sources. Here, current flows from one source through its transformer, the secondary buses, and back through the other transformer to the second source. Generally, this is neither desirable nor permitted.   "To prevent this operation, directional time–overcurrent relays (67, 67N) are applied to each transformer."   Figure 3c – Secondary protection with high-side breaker The single-line connections are shown in Figure 3b and Figure 3c, with complete three-line connections in the following figure.   Note: They operate only for fault current that flows into the transformer and trip the secondary breaker (52–1 or 52–2). This is also important in removing a secondary fault source for faults in the transformer bank. The phase relays (67) can be set on a low of the minimum tap.   Load current certainly flows through the relay, but normally not in the operating direction. The low tap continuous rating must not be exceeded by increasing the maximum load current. The 67-time setting must coordinate with the protection on the transformer primary. When used, the ground relay can be set on minimum setting and time, because coordination is not necessary.   Figure 4 – Three-line connections for reverse-phase and partial differential backup protection The inverse-time–overcurrent relays (51, 51N) provide bus protection and backup protection for the feeder circuits. These relays trip both 52–1 (or 52–2) and 52T. This is a partial differential connection and these units must be time-coordinated with the protection on the several feeders that are connected to the bus.   "Only two-phase relays are required, but the third relay (shown optionally in Figure 4) provides additional redundancy. When a ground differential is used, as illustrated in Figure 3c, 67N and 51N are omitted."   Ground-fault backup is provided by 51G, 151G, and 251G inverse-time overcurrent relays (Figure 3abc). Relay 251G provides bus ground-fault protection and backup for the feeder circuit ground relays. It must be time- coordinated with these. It trips the bus tie 52T, as the fault could be either on the bus or on the associated feeders.   If the fault continues to exist with the bus tie open, relay 151G trips breaker 52–1 (or 52–2). Thus, 151G must coordinate with 251G. If the fault persists, it is between the secondary breaker, in the transformer winding, or in the grounding impedance.   Relay 51G set to coordinate with 151G is the last resort. It trips the high-side or primary breaker to remove the transformer from the service.   III. Redundancy Requirements for Bulk Power Transformers   When transformers are connected to bulk power systems, redundancy requirements for related protection need to be addressed. To provide the required redundancy, two separate differential schemes may be applied.   "Redundancy for transformer faults may also be obtained by a differential scheme and sudden pressure."   In such an application, the sudden pressure protection needs to be supplied with additional protection for faults on the transformer bushings and leads, as sudden pressure devices will not respond to faults in these areas. Redundant schemes for disconnecting the transformer from the system when a high-side breaker is not applied can be obtained by using various combinations of the methods. Take an example, two separate transfer trip systems may be applied although they are expensive. A cheaper alternative is to combine a transfer trip scheme and a faulty switch. It may be possible to delay closing the fault switch for a few cycles to allow time for the transfer trip scheme, provided it is operational, to de-energize the failed transformer before the closing of the fault switch. This would spare the power system from being subject to a solid fault when the fault switch closes, whenever the transfer trip scheme works properly.   When a high-side breaker is applied and it fails to operate, breaker failure protection is required to enable isolation of a faulted transformer. The breaker failure scheme may require the application of a fault switch, transfer trip scheme, or a second interrupting device if other local breakers are not available to isolate the transformer.   FAQ     1. What is the use of transformer? Transformers are employed for widely varying purposes; e.g., to reduce the voltage of conventional power circuits to operate low-voltage devices, such as doorbells and toy electric trains, and to raise the voltage from electric generators so that electric power can be transmitted over long distances.   2. What are the 3 types of transformers? There are three primary types of voltage transformers (VT): electromagnetic, capacitor, and optical.   3. What is the basic principle of transformer? A transformer consists of two electrically isolated coils and operates on Faraday's principal of “mutual induction”, in which an EMF is induced in the transformers secondary coil by the magnetic flux generated by the voltages and currents flowing in the primary coil winding.   4. Does a transformer convert AC to DC? A transformer is built to transfer the energy from one circuit into another circuit by way of magnetic coupling. ... An alternating current creates a magnetic flux in the core on its way through the first winding, inducing the voltage in the others. It can convert high and low voltages, it cannot convert AC to DC.   5. What are the main parts of transformer? There are three basic parts of a transformer: a. an iron core which serves as a magnetic conductor, b. a primary winding or coil of wire and. c. a secondary winding or coil of wire.   6. What are the classification of transformer? Depending upon the type of construction used, the transformers are classified into two categories viz.: (i) Core type, and (ii) Shell type. Depending upon the type of service, in the field of power system, they are classified as: (i) Power transformers, and (ii) Distribution transformers.   7. Can a transformer work on DC? As mentioned before, transformers do not allow DC input to flow through. This is known as DC isolation. This is because a change in current cannot be generated by DC; meaning that there is no changing magnetic field to induce a voltage across the secondary component.   8. How do you convert a transformer? This conversion is made by winding two separate conductors around a common iron core. Applying an alternating voltage to the primary conductor produces current which sets up a magnetic field around itself. This is known as mutual inductance.   9. What are two components of no load current in transformer? The no-load current of a transformer consists of two components: The Magnetization Current iM is the current required to produce the flux in the transformer core. The Core-loss Current ih+e is the current required to make up for hysteresis and eddy current losses.   10. Which type of transformer core is most efficient? SHELL CORE. The most popular and efficient transformer core is the SHELL CORE, as illustrated in figure (4). As shown, each layer of the core consists of E- and I-shaped sections of metal. These sections are butted together to form the laminations.   11. What is the power factor of transformer? The power factor of a distribution transformer is between (0.75 to 0.80) when secondary is connected to u.p.f loads.   12. Why do we need Transformers? Transformers help improve safety and efficiency of power systems by raising and lowering voltage levels as and when needed. They are used in a wide range of residential and industrial applications, primarily and perhaps most importantly in the distribution and regulation of power across long distances.   13. What is the difference between a step up transformer and a step down transformer? A transformer that increases the voltage from primary to secondary (more secondary winding turns than primary winding turns) is called a step-up transformer. Conversely, a transformer designed to do just the opposite is called a step-down transformer.   14. Are transformers dangerous? There is no established evidence that the exposure to magnetic fields from powerlines, substations, transformers or other electrical sources, regardless of the proximity, causes any health effects.   15. Why transformer rating is in kVA not in kW? Copper losses (I²R) depends on current which passing through transformer winding while Iron losses or core losses or Insulation losses depends on Voltage. ... That's why the transformer rating may be expressed in VA or kVA, not in W or kW.    

SummaryHappy new year! The year of 2017 has become a past tense,whatever you experienced in the last year,let's celebrate the 2018's coming together ! Today I would like to show you a power projects about the high power voltage current  bridge driver using IR2153&IGBT. Project PhotoThis is a high power voltage current half bridge driver. About IGBT and IR2153IGBT based alf bridge board has been designed for multiple applications,like induction heater driver,tesla coil driver,DC-DC converters,SMPS etc. High current and high voltage IGBTs are used to serve high power requirements. IGBT NGTB40N120FL2WG from ON semi and IR2153 from Infineon semiconductor are important parts of the circuit, IR2153 is a gate driver IC including inbuilt oscillator, 40A/1200V IGBT can handle large current.  Gate driver circuit works with 15V DC and load supply 60V DC to 400V DC.  The IR2153D(S) are an improved version of the Popular IR2155 and IR2151 gate driver ICs, and incorporate a high voltage half-bridge gate driver with a front end oscillator similar to the industry standard CMO 555 timer. The IR2153 provides more functionality and is easier to use than previous ICs. A shutdown feature has been designed into the CT pin, so that both gate driver outputs can be disabled using a low voltage control signal. In addition, the gate driver output pulse widths are the same once the rising under voltage lockout threshold on VCC has been reached, resulting in a more stable profile of frequency vs time at startup. Noise immunity has been improved significantly, both by lowering the peak di/dt of the gate drivers, and by increasing the under voltage lockout hysteresis to 1V. Finally, special attention has been played to maximizing the latch immunity of the device, and providing comprehensive ESD protection on all pins.Oscillation frequency adjustable by onboard Trimmer potentiometer, frequency spans approx. 12 KHz to 100 KHz, duty cycle 50%. Note: Please take appropriate precautions as this power supply uses lethal voltages! Features Load Supply 60V to 400V DCGate Driver Supply 15V DCFrequency Span 12 KHz to 100 KHz, Other frequency range possible, alter R5, PR1, C8Duty Cycle Approx. 50%PR1: Trimmer Potentiometer to set the frequencyCN3: Logic Supply 15V DCCN1: Supply DC InputCN2 : L1 Load SchematicTesla Coil ExampleParts List  Connections Note 1: The circuit is provided with few extra components which may be used as per application requirement other components can be omitted as stated in BOM 2: Frequency span is determined by CT Capacitor (C8) and Trimmer Pot value, refer to datasheet for appropriate value for required frequency span. C8 1Kpf, R5=7k5 and PR1=50K provide frequency span 12 kHz to 100 kHz. 3:  Other Mosfet or IGBT can be used as per your current and voltage requirement. 4: This board also can be used as half bridge driver using IR2101/IR2104 and Mosfet, Header CN3 Pin1 HIN, Pin2 LIN, Omit following components R5, PR1, C8 to use IR2101/IR2105 5: IGBTs require large size heat sink. 

SummaryAccording to recent market research by Grand View Research,the global power electronics market will be valued at $39.2bn by 2025.To ensure electrical products and infrastructure are capable of supporting this 40% growth, REO UK is calling on laboratories and testing facilities to invest in stable DC power supplies for electrical testing. Electrical testing is a critical part of the design and development of power electronics and electrical components. Electricla Testing WorkElectrical testing involves running accurately monitored voltages through a component or product to ensure it is capable of withstanding and performing under specified currents. This ensures smooth performance and correct specification details once the tested equipment is on the market.  REO UK has worked extensively with test facilities and laboratories in the past and has identified a recurring problem of poor power quality affecting test accuracy. The company has previously launched ranges of electrical power supplies to provide stepless voltage adjustment to overcome this issue.  Steve Hughes,Managing Director of REO UK said: " Testing requires absolute accuracy to ensure  that products are reliable,safe and able to perform,if the market for power electronics is to reach its projected 40% growth in the coming decade, testing must be accurately controlled and reliable to ensure a consistently high standard of products."  Test Facilities disadvantage"Unfortunately,we often see that test facilities lack this control, either due to inaccurate electrical equipment or electromagnetic interference (EMI) making the current unreliable.” Up to now, the company has  stepped up its focus on test facilities with its new REOLAB 1000E electronic DC power supply for test equipment. The product is designed for use in testing the operating current of semiconductor diodes and rectifiers, as well as the maximum DC reverse voltage of a system up to 1,200V.  “Our new REOLAB 1000E helps to tackle the lack of electrical control with its stepless voltage adjustments and current tolerance of ±1%,” continued Hughes. “This tolerance level means that the supplied power is highly accurate and controllable.“In addition to this, the REOLAB range has a design that complies with electromagnetic compatibility (EMC) standards to prevent creating power quality problems. This ensures test and laboratory facilities can test properly and effectively with minimal concerns over unstable loads.” 

SummaryIncreasing demand for energy and power encourages companies operating in energy and power industry to adopt solutions that can help them enhance production output with minimum errors and reduced down-time on a global scale. The products are offered specifically for the energy sector to enhance operations in the energy data management area. Industry 4.0 solutions help power plant owners, operators, and Original Equipment Manufacturers (OEMs) in the power industry make improved business decisions based on performance and operational readiness of their plant equipment.According to the MarketsandMarkets forecast, the Industry 4.0 market in energy and power was valued at $1.30m in 2016 and is expected to reach $3.22bn by 2022, at a CAGR of 16.33% between 2017 and 2022. IoT and Power IndustryIndustry 4.0 is being led by IoT and it plays an important role in condition monitoring and predictive and proscriptive maintenance of assets.Plant operators need to monitor and control the plant more efficiently, and for doing so, the adoption of advanced technologies such as HMI is increasing significantly in the energy and power industry. IoT provides flexibility to accommodate new energy sources, better management of assets and operations, greater reliability and enhanced security.  Big Data to Transform Power IndustryThe energy and power industry has recognised the benefits of big data as it plays a vital role in solving business problems in utility companies.In this vertical, the big data solutions are gaining traction in various processes such as seismic data analysis, smart grid analytics, and data analysis related to production, testing, logging, and many other operations. Each year, smart grids and smart meters generate hundreds of terabytes of data, which include unstructured and semi-structured data. Companies in the energy and power industry have analysed this huge amount of data to get real time access to the situation. Being largely customer-centric, the energy companies are also making a shift toward providing more personalised products and services to their customers. Big data plays an important role in providing trends and patterns by analysing the data, which in turn are useful for product and service upgradation and enhancement. Real Time Monitoring in Battery ManagementReal-time monitoring is a technique that allows you to determine the current state of queues and channels within a queue manager. The information returned is accurate at the moment the command was issued.It can provide frequent information on batteries which can help protect the batteries.Real time monitoring in battery management can help replace manual checks by information available at monitoring systems. Sensor modules collect the voltage and temperature data from the batteries and data is transferred in real time can help supervisors identify issues if any and which will lead to operational efficiency.   Predictive MaintenancePredictive maintenance (PdM) techniques are designed to help determine the condition of in-service equipment in order to predict when maintenance should be performed. This approach promises cost savings over routine or time-based preventive maintenance, because tasks are performed only when warranted.It helps in lowering operating and capital costs by facilitating proactive servicing and repair of assets while allowing more efficient use of maintenance personnel and replacement components.It enables companies to accurately diagnose and prevent failures in real time, which is vital in critical infrastructure applications.  Battery failures can prove to be highly expensive in terms of repair costs, in addition to the delay in transporting goods from the resulting downtime. Predictive battery analytics can also help predict battery failures which allows the supervisors to reduce reliability risk and improve uptime.The need for longer battery life, reduced energy consumption, and lower costs will lead companies to provide intelligent solutions. Cognitive Power Electronics SystemsPower electronics systems equipped with intelligence unit can monitor data from sensors and the data can be used to detect faults in the electronic system for real time optimisation of an application.A power converter with monitoring capabilities would be able to detect impedance changes of a battery,enter into a safe state and send information to external systems for further evaluation. Article from MarketsandMarkets Research Private Ltd.Edit by Kynix

Have you heard of Silicon carbide power devices yet? Researchers are rolling out a new manufacturing process and chip design for silicon carbide (SiC) power devices, which can be used to more efficiently regulate power in technologies that use electronics. The process -- called PRESiCE -- was developed to make it easier for companies to enter the SiC marketplace and develop new products.(Silicon carbide power devices, like the one shown here, are more efficient than their silicon counterparts.)"PRESiCE will allow more companies to get into the SiC market, because they won't have to initially develop their own design and manufacturing process for power devices -- an expensive, time-consuming engineering effort," says Jay Baliga, Distinguished University Professor of Electrical and Computer Engineering at NC State and lead author of a paper on PRESiCE that will be presented later this month. "The companies can instead use the PRESiCE technology to develop their own products. That's good for the companies, good for consumers, and good for U.S. manufacturing." Power devices consist of a diode and transistor, and are used to regulate the flow of power in electrical devices. For decades, electronics have used silicon-based power devices. In recent years, however, some companies have begun using SiC power devices, which have two key advantages. First, SiC power devices are more efficient, because SiC transistors lose less power. Conventional silicon transistors lose 10 percent of their energy to waste heat. SiC transistors lose only 7 percent. This is not only more efficient, but means that product designers need to do less to address cooling for the devices. Second, SiC devices can also switch at a higher frequency. That means electronics incorporating SiC devices can have smaller capacitors and inductors -- allowing designers to create smaller, lighter electronic products. But there's a problem. Up to this point, companies that have developed manufacturing processes for creating SiC power devices have kept their processes proprietary -- making it difficult for other companies to get into the field. This has limited the participation of other companies and kept the cost of SiC devices high. The NC State researchers developed PRESiCE to address this bottleneck, with the goal of lowering the barrier of entry to the field for companies and increasing innovation. The PRESiCE team worked with a Texas-based foundry called X-Fab to implement the manufacturing process and have now qualified it -- showing that it has the high yield and tight statistical distribution of electrical properties for SiC power devices necessary to make them attractive to industry. "If more companies get involved in manufacturing SiC power devices, it will increase the volume of production at the foundry, significantly driving down costs," Baliga says. Right now, SiC devices cost about five times more than silicon power devices. "Our goal is to get it down to 1.5 times the cost of silicon devices," Baliga says. "Hopefully that will begin the 'virtuous cycle': lower cost will lead to higher use; higher use leads to greater production volume; greater production volume further reduces cost, and so on. And consumers are getting a better, more energy-efficient product." The researchers have already licensed the PRESiCE process and chip design to one company, and are in talks with several others. "I conceived the development of wide bandgap semiconductor (SiC) power devices in 1979 and have been promoting the technology for more than three decades," Baliga says. "Now, I feel privileged to have created PRESiCE as the nation's technology for manufacturing SiC power devices to generate high-paying jobs in the U.S. We're optimistic that our technology can expedite the commercialization of SiC devices and contribute to a competitive manufacturing sector here in the U.S.," Baliga says. The paper, "PRESiCE: PRocess Engineered for manufacturing SiC Electronic-devices," will be presented at the International Conference on Silicon Carbide and Related Materials, being held Sept. 17-22 in Washington, D.C. The paper is co-authored by W. Sung, now at State University of New York Polytechnic Institute; K. Han and J. Harmon, who are Ph.D. students at NC State; and A. Tucker and S. Syed, who are undergraduates at NC State. The work was supported by PowerAmerica, the Department of Energy-funded manufacturing innovation institute that focuses on boosting manufacturing of wide bandgap semiconductor-based power electronics. ref.KY56-PZTA06KY41-SL12T1G

（Researchers have developed an algorithm that allows residential customers to share power from the renewable energy sources in their homes during an outage.） If you think you can use the solar panels on your roof to power your home during an outage, think again. During an outage, while your home remains connected to the grid, the devices that manage your solar panels are powered down for safety reasons. In other words, this permanent connection to the grid makes it impossible for homeowners to draw on power generated by their own renewable energy resources. A team of engineers at the University of California San Diego wants to change this. They have developed algorithms that would allow homes to use and share power from their renewable energy sources during outages by strategically disconnecting these devices, called solar inverters, from the grid. The algorithms work with existing technology and would improve systems' reliability by 25 to 35 percent. Researchers detail the algorithms and their applications in a paper they presented at the American Control Conference in Seattle, Wash. "We were inspired to start investigating a way to use renewable power during outages after Hurricane Sandy affected eight million people on the East Coast and left some without power for up to two weeks," said Abdulelah H. Habib, a Ph.D. candidate in mechanical engineering at UC San Diego and the paper's first author. Our Society is Dependent upon ElectricityJust a few hours without power can cause massive losses to both product and revenue.We rely on electricity much more than we realize. Even if you live "off the grid," as I did for years, you are still living in a world and a society that is deeply dependent upon electricity. If the power is out for a few hours, we have all experienced that; of course you'll be fine. Maybe you will be a little bored and inconvenienced, but if the outage is lengthy and widespread, the consequences can be much more severe, even deadly. What would happen if the electricity was out for a week?Every year, 7 million customers experience power outages. Outages that last more than 5 to 10 minutes cost customers more than $80 billion each year. How the Algorithm WorksThe innovation here is the algorithm's capability to prioritize distribution of power from renewable resources during an outage. The equations take into account forecasts for solar and wind power generation as well as how much energy storage is available, including electric vehicles, batteries and so on. The algorithm combines that information with the amount of energy that the residents are projected to use as well as the amount of energy that a cluster of homes can generate.The algorithm could also be programmed to include a priority function, based on different parameters. For example, customers who are willing to pay more could get priority to get power during an outage. Or customers who generate more energy than they produce during normal operations would not lose power during an outage. More importantly, the algorithm could give priority to customers who are in urgent need of power, because they use life support equipment, for example. Ref.KY605-LC-R064R5PKY605-0860-0004