Correctly distinguish inrush and internal fault has been the focus of transformer protection

Power transformer is extremely important power system equipment, transformer differential protection is the main protection. Load switching or external short circuit fault clearing voltage generated when a  power transformers  current recovery, the size of a few comparable internal fault currents. Can correctly distinguish inrush and  air circuit breaker  transformer protection has been the focus of a variety of magnetizing inrush current  Electric energy meter  method largely based on Kirchhoff's law, there is in principle a defect; several differential protection new theories, new technology also needs to be further improved in practice. With the increasing size of the power system, load tap more extensive application, which also produced a lot of problems related to.

Generator Circuit Breaker If you choose incorrectly, the circuit breaker will cause serious harm

Of the problem with the continuous development of science and technology and people's safety awareness generation equipment continues to improve, the generator breaker dedicated selection and use more and more cause for concern and attention, especially for large and very large  Electric energy meter  machinery exports particular attention to the choice of the circuit breaker . If you choose incorrectly generator circuit breakers , circuit breaker itself even be connected to the generator generators and other electrical equipment circuit causing serious harm and  mcb circuit breaker  losses, such as the explosion occurred breakers , generators burned, excitation transformer and plant with variable burned and other serious accidents , and will magnify the accident . For small hydro , the past mostly use an ordinary type of oil circuit breaker , vacuum circuit breakers , SF6  Voltage stabilizer . , especially in recent years , the choice of more and more common vacuum circuit breaker , such a choice is not comply with GB GB/T14 82 4-93 " generator breaker general technical conditions" and industry standards DL42 7-91 " indoor type GCB ordering technology " requirement, does not conform to international common standards However, the parties have failed to pay sufficient attention to this cause .

Operating status of power transformers in the power system security and reliability has a pivotal position

Operating status of power transformers in the power system security and reliability has a pivotal position. Power transformers in operation in the event of damage  air circuit breaker , will directly affect the power grid, causing huge economic losses. Papers for the power transformer fault characteristics were studied based on ant colony  Electric energy meter  the power transformer fault localization method to achieve with less cost, more quickly and accurately detect the power transformer fault. Specific research work is as follows: For the common faults of power transformers, power transformers a lot of trouble for analysis.

Ultra-precision electromechanical systems to further improve the accuracy fast motion

Ultra-precision micro-displacement piezoelectric drive platform as a variety of modern microelectronics manufacturing equipment, a core component of its R & D directly affect the level of national electronic information industry's technological progress. However, the inherent piezoelectric actuator hysteresis characteristics, causes a serious decline in system accuracy, and even lead to instability of the closed-loop system. Therefore, in order to further improve the ultra-precision  Electric energy meter  precision electromechanical systems, nano-processing and operations to meet the requirements of the urgent need to study hysteresis compensation control theory and method. This paper studies the piezoelectric  Voltage stabilizer  compensation fuzzy control method, the design of two-dimensional parallel micro-moving platform, using a multi-input single-output fuzzy system for piezoelectric  power transformers  characteristics of modeling, real-time simulation system is constructed, on this basis, to achieve a hysteresis compensation fuzzy control experiments to determine the equivalent. First, the use of composite double parallel bar type flexure hinge mechanism, designed with a very low degree of coupling of the two-dimensional motion parallel micro-moving platform, its structural optimization calculations and finite element analysis using EDM wire cutting is completed, to achieve the relevant testing and experiments.

Current manufacturing artificial current zero crossing will be very difficult

An important difference is that the former use of artificial zero-crossing method, the vacuum on the contacts current zero extinguish the arc, which is borrowed from the natural  Electric energy meter current arc. Although there has been applied to the VCB AC power system technology has matured, but it does not solve the current high rate of rise of the power system short-circuit current breaking issues. Since ACVCB is rated opening distance (a few millimeters to tens of millimeters) under breaking, usually takes a  electric meter  to tens of milliseconds, when the DC short circuit current rise rate 20A/μs when the short-circuit current  lectri cenergy meter will reach 100kA or more. Accordingly, to such a high current manufacturing artificial current zero will be very difficult, if achieved, will also lose the breaking limit of significance. A small opening in breaking away from the direct short-circuit current high rate of rise can be a good solution to the problem of excessive current. But a small opening under vacuum from the media recovery, but it is restricting the application of the method of the key issues. - At present, domestic and foreign media for the recovery characteristics of vacuum almost always based on a few millimeters to tens of millimeters at rated basis.

Transformation and cast resin dry type epoxy resin dry type transformer wrapping

Dry-type transformers are insulated with NOMEX paper is impregnated with resin dry type transformer and cast resin insulation dry-type epoxy transformation and wrap dry change. The former is a non-locked-in type, the latter two are locked-in type. For temperature  Voltage stabilizer , non-encapsulation type is mainly by convection and radiation to heat directly into the atmosphere, and the encapsulation type must first heat conduction through the way, the heat transmitted through the resin  circuit breakers  the winding, winding temperature difference between the surface of the resin can not be ignored Therefore, the second method is particularly suitable for cast resin dry type transformer temperature rise. That the winding Heat is  Electric energy meter  the surface by heat conduction, mainly by convection and radiation and scattered into the air, therefore, temperature rise should include two parts, heat conduction and convection.

Ensure dry type power transformers do not need special maintenance and management

Single-chip intelligent control technology made ​​into dry-type transformer temperature controller, than using discrete components in terms of performance and error control techniques such as a step forward, high precision, small size, multi-function, performance, quality, reliability and operating easy maintenance. Measurement, control  Electric energy meter principle whether the normal safe operation, is known for its winding temperature rise to decide. Dry-type transformers are three-phase, and the A-phase, B-phase and C phase three windings, each phase  mcb circuit breaker  to keep temperature, dry-type power transformers in order to ensure safe operation, and do not need special maintenance management, you need to configure the temperature patrol control instrument (referred temperature controller).

Combined with the most advanced data storage technology design

New air-cooled dry-type transformers generation of computer temperature controller, using the U.S. production of single-chip computer to control the core, combined with the most advanced data storage technology designed to make the whole product  air circuit breaker  scaled to a new level. And traditional analog and digital circuit temperature controllers, because using high-performance micro-controller, the product can   Electric energy meter  number of required electronic  circuit breakers  for more than half of the circuit design and structural design greatly simplified, so that a very greatly improve the operational reliability of the entire product. The analog and digital circuit temperature controller failure rate is very high.

Medium voltage vacuum circuit breaker has made great progress, and achieved good results

Medium voltage vacuum circuit breaker has made great progress, and achieved good results, especially in the performance of the 12 kV voltage level, vacuum circuit breakers predominant. Currently, 12 kV outdoor vacuum circuit breakers are equipped with a  Electric energy meter  actuator actuator majority. Currently, outdoor vacuum circuit breaker products tend to focus on the design of the main circuit breaker and  mcb circuit breaker e, while ignoring the actuator in operation life. All circuit breakers life is ultimately reflected in the contact switching operation, while the switching operation is achieved through the actuator. Therefore, the actuator's work performance, reliability and quality merits, the circuit breaker performance and reliability plays an extremely important role.

Select OK suitable for a specific application circuit protection devices

Select OK suitable for a specific application circuit protection devices is not difficult, but does require some thought fee. If the electrical and electronic equipment used in the design specifications of making a very loose side of the circuit  Electric energy meter , the device can easily be damaged by shock due to power and led to the disastrous consequences of the fire, on the contrary, if the strict specifications of making a very biased circuit protection devices will cause annoying frequent tripping. The  Air circuit breaker  breakers are mainly thermal circuit breakers, magnetic circuit breakers and earth leakage circuit breakers and other types. In the choice of the circuit breaker, the designer only needs to consider the following characteristics of the circuit, the circuit breaker should also be considered,  electric meter  the installation location and case size limitations: ● The nominal applied ac or dc voltage ● Single-phase, multi-phase, and the number of poles ● applicable national electrical standards and safety management agency standards ● short-circuit breaking capacity a thermal breaker hot series with the circuit breaker using a bimetal. Current overload causes the heat generated during the deformation of the bimetal, so that the circuit breaker. Compared with the fuse, thermal protector has a significant advantage, in that can be reset after tripping. They can also be protected as the power on / off switch. As the temperature increases, the thermal circuit breaker trip speed, and often at a lower current level tripping occurs.

The digitized output and adapt to network wiring and other obvious advantages to meet the miniaturization of power system equipment

With modern power systems to high pressure, long-distance, large-capacity in the direction of, the traditional electromagnetic transformer insulation because of its complex structure, magnetic saturation, bulky, difficult to meet the cost of the disadvantages of modern development. In recent years, the emergence of electronic transformer, with its digital output and adapt to network wiring and other obvious  Electric energy meter  the power system equipment miniaturization, intelligence, good safety and the quality of economic operation and high reliability needs of the digital substation play an important role. Therefore, the combination of digital  Voltage stabilizer  equipment detect trends and needs, establish electronic transformer model is an increasing need for electronic transformer Transfer Characteristics and study of the impact on the protection of great  Circuit breaker  significance and practical value. This paper mainly electronic current transformers as the main line, the first in analyzing its structure and measuring principle based on the active-type software completed electronic current transformer sensor head and analog signal processing system modeling work, derive the transfer function model and the simulation parameters into the prototype model of the frequency characteristics and error factors.

Solenoid valve spool valve sleeve and spool with a small gap, are generally one-piece assembly

Solenoid valve coil burned out, remove the solenoid valve wiring, measured with a multimeter, if open, the solenoid valve coil burned out. Moisture causes the coil, magnetic flux leakage caused by Electric energy meter, causing the coil current is too large to burn, so to prevent rainwater from Voltage stabilizer the solenoid valve. In addition, strong spring, reaction force is too large, too few coil turns, suction can not make the coil burnt. Emergency treatment, can be manual button on the coil from the normal working hours of the "0" bit hit "1" bit, making the valve opens.
Solenoid valve spool valve sleeve and spool with a small gap (less than 0.008mm), are generally one-piece assembly, when there are mechanical impurities into or too little lubricant, it is easy to get stuck. electric meter are available hold into the wire hole from the head to make it bounce. The fundamental solution is to remove the solenoid valve, remove the spool and spool cover, with CCI4 cleaning kit allows flexible movement of the valve spool. Demolition should pay attention to the various components of the assembly sequence, and external wiring position for re-assembly and wiring is correct, also check whether the plug hole injector lubricator, lubricant is adequate.

Resistance changes from zero to the nominal value of Euro and no transitions or jitter phenomenon indicates normal potentiometer

First measure the resistance value between two fixed ends is normal, if Europe is infinite or zero or nominal power transformers the larger, exceeding the permissible limit, are described corrupted; resistor resistance to normal, then a multimeter table pen potentiometer wiper, another table pen potentiometer (variable resistor) either a fixed end, slowly rotating mandrel, observe whether smoothly changing hands, mcb circuit breaker one end to the other end of the rotation, the resistance from zero Europe changes to the nominal value (or vice versa), and no transitions or jitter Electric energy meter, then the potentiometer is normal, if there is in the process of rotating hopping or jitter phenomenon, indicating that the sliding resistance of body contact points are bad.

Measure different resistor values ​​selected multimeter different multiplier block

The power block with a multimeter for resistance measurement, measure different resistor values ​​for selected Electric energy meter multiplier block. For Analog Multimeter, because power block shows the number of non-linear, the greater the resistance, showing the number of the more dense, so select the appropriate power transformers bigger hands deflection angle, indicating at 1/3 to 2/3 full scale readings more accurate. If the measured resistance value exceeds the error range resistors, resistance is infinite, the resistance or the resistance instability of 0, indicating that the resistor is broken.
Take note that in the measurement Circuit breaker hands do not come into contact two pins, it would hand the resistance presented in parallel with the measured resistance, impact measurement accuracy. In addition, the case can not be charged with a multimeter power block detection circuit resistor values​​. Online testing should first off, and then disconnect it from the circuit resistance, then measure.

No fault breaking phenomenon is mainly due to adverse weather conditions such as storms caused

Traditional drop-out fuse of trouble breaking phenomenon is mainly due to adverse weather conditions such as storms Electric energy meter When the contacts are mounted on a fully enclosed stainless steel cover after fouling avoid electric meter sand and snow, resistance to natural disasters, the performance is very strong, thus eliminating the trouble-breaking electric transformer the safe operation of the line to provide a reliable guarantee . While increasing the contact surface of the conductor, and the silver-plated contact surfaces significantly reduce the contact resistance, the contact heating and flaming phenomenon due to oxidation corrosion can be avoided, the interpolation type structure, but also to solve the pull switch operation caused by the arc short-circuit problem.

Because electromagnetic vibration causes vibration welding crack, resulting in leakage

Mainly poor weld quality, there Weld, Desoldering, weld pinholes exist, trachoma and other defects, power transformer factory due to flux and paint coverage will be exposed  electric transformer  risks, in addition to the electromagnetic vibrations cause welding vibration crack, resulting in leakage. For leakage phenomenon has emerged, first  electric meter  leakage points, can not be missed. Severe leakage can be used for parts or sharp punch flat shovel and other metal tools leakage points riveting die, after  Electric energy meter  leakage control surface is clean, the current use of polymer composites curing, curing can achieve long-term leakage control purposes. Seals leaking oil: seal bad reasons, usually along with the lid sealed box is the use of oil and rubber truncheon or rubber gasket seal, if not handled properly it can cause joints oil leakage fault.

Generates magnetic flux perpendicular to the silicon surface and cause increased noise

Each level of the iron yoke and the sheet width ratio of the stem, they should be equal to the ratio of the cross-sectional area. This prevents the magnetic flux from the stem into the yoke, because the generated magnetic flux perpendicular to the silicon surface and cause  electric meter  noise. Core using 45 ° miter joints, can reduce the corner  Circuit breaker  core, so that the core noise reduction 4dB. To ensure the mechanical  Electric energy meter  of the core of the premise, the seam area should be smaller overlap area, so that the corner of the magnetic flux through the non-silicon area is reduced in the rolling direction, in order to reduce noise.

Various devices connected in series with the current loop current transformer secondary

Measuring circuit is divided into current loop and voltage loop. Various devices connected in series with the current loop current transformer secondary side (5A), current transformer primary side is unified into a 5A load current measuring current. Metering and protection respectively respective transformer (high precision metering transformers),  mcb circuit breaker  and measurement series with the ammeter meter, power meter and power factor meter current terminal. Protection measure current in series with the protection relay terminals.  Electric energy meter  will generally be concentrated in one measurement and protection, respectively, measured at current terminals and protection current terminal.
Voltage measuring circuit, 220/380V low pressure system directly connected to 220V or 380V, 3KV high pressure system above all through the various levels of voltage transformer High  Circuit breaker  unified 100V voltage, voltmeter and power meter, power meter and power factor meter voltage coils are connected to its terminals and 100V voltage bus. Computer protection unit protection voltage measured voltage and unity as a voltage terminals.

Circuit breakers rated short circuit breaking capacity

In the civil design is mainly used for low-voltage circuit breaker overload, short circuit, over current, loss of voltage, grounding, leakage, dual power automatic switching and infrequent start  Electric energy meter, operation and other purposes, the choice of in addition to compliance with the principle of the use of low-voltage electrical equipment and other basic principles of Voltage stabilizer characteristics (see the distribution of industrial and civil design manual) still should be considered in addition the following conditions:
A) not less than the rated voltage of the circuit breaker rated voltage lines;
2) Rated current breaker with o mcb circuit breaker device is not less than the rated current of the line to calculate the current;
3) circuit breakers rated short-circuit breaking capacity not less than the maximum short-circuit current;
4) Select the type of distribution to be considered a short delay circuit breaker breaking capacity and delay protection interstage match;
5) breaker undervoltage release voltage rating equal to the rated line voltage;
6) When used for motor protection, then select the circuit breaker motor starting current to be considered at the starting time and make no action; design calculations see "industrial and civil Distribution Design Handbook";
7) breaker selection should also consider the breaker and circuit breakers, circuit breakers and fuses selective cooperation.

Akira power supply circuit for controlling electrical effects

AC contactor low voltage motor control system is widely used, accounted for a large proportion. Because electromagnetic contactor works feature Akira power occurs when the grid will cause electromagnetic or short-time working coil contactor power or low voltage, resulting current is maintained by the pull dynamic and Electric energy meter suction less than release force of the spring, generates the contact trip down to release the important reasons. Electromagnetic AC circuit breakers characteristics: electric meter IEC standards, 80% of the rated voltage threshold reliable pull-in voltage. Threshold voltage of the rated working voltage release of 20-70%, the electromagnetic field use AC contactor are generally in the 50% of the nominal voltage release, so because of "shake" cause electromagnetic contactor uncontrolled nature trip downtime is caused by the principle