[technical analysis] Analysis of main transformer arc suppression coil operation and maintenance and troubleshooting

【Abstract】With the development of China's national power, the pressure of the power system also increases. The arc suppression coil plays an important role in the operation of the substation. The arc suppression coil plays a compensating role in the small current grounding system and plays the role of eliminating arcing at the grounding point.

【Keywords】 arc suppression coil; operation and maintenance; problem solving

1 Introduction

The appearance of the arc suppression coil is similar to that of a single-phase transformer. The arc suppression coil is basically applied to a neutral point ungrounded power grid. Inside the arc suppression coil, there is an iron core inductance coil with a gap. The inductor current is from the arc suppression coil. The medium flow can compensate for the capacitive current in the power grid, which can eliminate the effect of the arc at the ground point, stabilize the ground connection, and can solve some problems caused by the intermittent. Therefore, in the maintenance of the installations in the power system, it is necessary to increase the operation and maintenance of the arc suppression coils. If the operation of the arc suppression coils is a problem, it must be handled for the first time to prevent more serious problems. occur.

2 Some matters that must be paid attention to in the operation of the arc suppression coil

(1) In the process of the operation of the arc suppression coil, the operation and maintenance personnel should perform special operation monitoring on the capacitance and current, inductance and current in the arc suppression coil, and the position of the arc suppression coil gear has the above operating temperature. The instructions must also be given sufficient attention to monitoring. In order to monitor the oil-filled arc-suppression coil, it is also required to monitor whether the oil position of the arc-extinguishing coil is within the specified position range, whether the color of the used oil is transparent, and the color of the oil is not changed to black, and whether the body of the arc-extinguishing coil is to be checked. There is a problem of oil leakage.

(2) When there is no ground fault in the operation of the arc suppression coil, the normal operation of the arc suppression coil should be no sound, and the isolation switch of the arc suppression coil should also be in contact with no problem. The light that detects the grounding is in the off state and is detected. Whether the signal sent by the device is not a problem, whether the arc extinguishing coil operating gear is in the specified position, and residual flow is also in the specified normal standard.

(3) When there is a problem of grounding during the operation of the arc suppression coil, the maintenance personnel of the power supply company should monitor the oil temperature at the operation site of the arc suppression coil, and whether the maximum temperature of the oil temperature exceeds 95°C. Whether the compensation degree has reached the specified level, and whether there are other abnormal sounds during the operation of the arc suppression coil, in which the temperature of the damping resistor is normal, and the operation and maintenance personnel must pay attention to the total time for the grounding operation of the arc suppression coil can not be increased. For the normal time written on the nameplate, if the time is too long, the operating circuit in question should be cut off.

(4) During the operation of the power system, maintenance personnel must monitor the neutral point displacement voltage. If the displacement voltage exceeds the specified value and the ground indicator on the arc suppression coil is bright, the maintenance personnel It is necessary to deal with the problem in accordance with the appropriate treatment methods to detect the location of the problem.

(5) Prior to commissioning and stopping the operation of the arc suppression coil and direct adjustment of tap operation by hand, the power grid must be checked to determine if there is a single-phase grounding problem, and whether the current at the grounding is detected Less than 10A, if the ground current is less than 10A, corresponding maintenance work can be performed.

(6) When the operation and maintenance personnel inspects the operation of the arc suppression coil, if an abnormal sound or discharge sound is found inside, the faulty grounding line should be cut off and the operation should be completed. The arc-extinguishing coil stops running. Finally, the body of the arc-extinguishing coil is tested in a professional manner. If maintenance and repair personnel find that the arc-extinguishing coil has smoke and other problems, the circuit breaker shall be used in time. The upper power supply of the arc-extinguishing coil is cut off, and finally the arc-suppression coil isolating switch is turned to the open position.

(7) When operation and maintenance personnel remove other transformers from the neutral point of the transformer on the arc suppression coil, maintenance personnel should first turn off the isolation switch on the arc suppression coil, and then perform the switching operation. Do not connect the arc suppression coil to the neutral point of multiple transformers when doing this operation.

(8) Operation and maintenance personnel should repair the arc-extinguishing coils in question and turn off the isolating switch on the arc-extinguishing coil to the open position. Then, stop the transformer in operation and perform the operation at the time of power transmission. The above operation is exactly the opposite. If a single-phase grounding occurs during the operation of the system, maintenance personnel cannot change the gear position on the bus.

3 How to deal with abnormal arc suppression coils

When the following problems occur during the operation of the arc suppression coil, the maintenance personnel must immediately adopt a professional operation method to cut off the processing by using a high-voltage circuit breaker or using a transformer-disabled method:

(1) There is a problem of damage when a normally used explosion-proof door is present, and a problem of fuel injection occurs on the explosion-proof door.

(2) If a problem of oil leakage occurs while the system is running, other sounds are issued while the oil leaks.

(3) If there is a crack or crack on the sleeve in use, this can cause discharge or grounding problems.

(4) The arc suppression coil emits white smoke or produces a fire phenomenon. If maintenance and inspection maintenance personnel find the following problems in the operation of the arc suppression coil, the operation and maintenance personnel should immediately take action to disable the arc suppression coil:

(1) Operation and maintenance personnel detect that the temperature of the arc suppression coil exceeds the specified limit.

(2) When the operation and maintenance personnel detect that there is a poor contact with the switching device that performs the decomposition.

(3) Operation and maintenance personnel detected that the grounded lead has been broken or there is a problem of poor contact.

(4) Operation and maintenance personnel detected that the effect of the isolation switch was not obvious or even impossible to use.

If there is a problem with the grounding abnormality in the power system, the operation and maintenance personnel cannot disable the operation of the arc suppression coil. The maintenance personnel can only take measures to supervise the oil temperature of the upper layer of the arc suppression coil. If the oil temperature exceeds 95°C, the operation and maintenance personnel must immediately take professional measures to solve the problem of single-phase grounding. If the effect of the measures taken is not obvious, the single-phase grounding problem cannot be solved well. The problematic line must be cut off and the running arc suppression coil must be stopped.

When it is detected that the operation time of the arc suppression coil exceeds the operating time specified on the nameplate, the maintenance personnel must take professional measures to disconnect the circuit breaker on the transformer and then take measures to eliminate it by using the isolation switch. After the arc coil is cut off, use the prepared fire extinguishing equipment to extinguish the fire.

4 operation and maintenance personnel on the detection of arc suppression coil operation and processing methods

If a single-phase grounding, series resonance occurs in the power grid during operation, and the degree of displacement of the neutral point is detected to exceed the relevant regulations, the alarm bell installed on the arc suppression coil will operate and produce a harsh sound. When the action photon card also becomes bright from a dark state, the indicator light on the arc suppression coil also becomes bright, and the scale value displayed on the neutral point displacement voltmeter also becomes large; if a ground phase voltage is detected When the state is zero, this indicates that a single-phase grounding problem has occurred. If the above problems occur, the maintenance personnel should immediately perform the following operations to resolve the failures and reduce the greater losses.

The maintenance staff of the operation and maintenance first checks whether there is a problem in the signal sent by the arc suppression coil, and then immediately reports the grounding property, the grounding phase, the operation status of the arc suppression coil, and the scale value displayed on the meter to the dispatcher, and take measures. The problem occurred as soon as possible.

5 How to Find a Grounding Problem

During system operation, if a phase on the arc-extinguishing coil in the power system is grounded, then the voltage of the other two phases will rise. This situation is very important for the operation of the power system. The big hidden danger will also break down the insulation of the other phase, which will cause the system to be short circuited in two phases. Therefore, the maintenance and repair personnel of the company must take corresponding measures to detect where the grounding occurs, so that the problems that occur can be quickly resolved. Operation and maintenance personnel need to take the following measures:

(1) Operation and maintenance personnel should check whether there is any equipment in the power system that has just been put into use. These new equipment are likely to leak.

(2) Operation and maintenance personnel should use parallel circuits to transfer power and at the same time detect whether there is a grounding condition.

(3) Operation and maintenance personnel replace faulty equipment that has detected problems with normal equipment.

6 Summary

After the above, during the actual operation of the arc suppression coil, maintenance personnel must inspect the various factors that can affect the arc suppression coil, so as to minimize the hidden dangers during the operation of the arc suppression coil. The operation of the arc suppression coil can be normally operated. The normal operation of the arc suppression coil can make the operation of the power system more reliable, minimize power accidents during the power supply process, and provide enterprises with more excellent services.

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