The purpose of testing the impact of closing the transformer into operation before

The purpose of the impact of closing the transformer has two tests:
When opened load transformer, it is possible to produce over-voltage operation. When ungrounded or Petersen coil grounded neutral point in the power system, over-voltage amplitude up to 4 to 4.5 times the phase voltage; directly grounded neutral point, up to 3 times the phase voltage. In order to check the dielectric strength of the transformer can withstand full operating voltage or over-voltage, impact testing to be done.  electric meter  into no-load transformer inrush current is generated, the value of up to 6-8 times the rated current. The inrush current begins to decay rapidly, generally over 0.5 seconds is reduced to 0.25 to 1 to 0.5 times the rated current value, all in a longer decay time, up to large-capacity transformers tens. Due to a large  Voltage stabilizer  generated electric power, in order to assess the mechanical strength of the transformer, while the initial assessment of the inrush current decay protection devices can cause malfunction, need to do the impact test.

Transformer protection misoperation pressure release case studies

Main transformer pressure relief protection, as important non- power transformer protection , depending on the fuel tank body release valve micro switch to achieve. That is when the oil inside the device accidents , oil tank is vaporized , producing large amounts of gas , so that a sharp increase in pressure inside the tank . When the tank pressure  power transformers opening pressure rises to its micro switch quickly closed, while the rapid release valve opens within 2ms, so the tank pressure rapidly decreases, while its micro switch quickly closed, turned tripping circuit , broken open each side of the transformer circuit breaker .  electric transformer  the deformation of the transformer tank , or even burst. However, the actual operation, the transformer pressure relief protection malfunction accidents often occur. Shandong SISHUI ​​power company belongs 110kV substation Kim Chong , occurred because of the pressure relief protection transformer malfunction , each side of the transformer circuit breaker tripped , causing power loss of pressure in the station accident . Kim Chong 110kV substation is an important hub for the western grid substation Surabaya . Powered by 110kV and 110kV lines Jinzhuang song Si line, the bridge connection , a single mother of segmented , double main transformer mutual standby operation.

Transformer differential protection trip inspection process

Transformer differential protection trip, it should be checked and processed as follows: (1) Check the transformer body without exception, porcelain differential within the scope of protection checks whether flashover, damage, if there is a short circuit 2 lead if the transformer differential protection. no significant fault within the device, you should check whether the secondary circuit protection and fault, if there are two DC circuit ground. 3 or more after inspection  electric meter , should be sent immediately after the removal of a load test, and then try to send the trip may not be sending. 4 If the relay or secondary circuit due to failure or  Electric transformer  caused by moving the DC grounding points, differential protection should be out of operation, the transformer power transmission, and then deal with the secondary circuit and DC ground fault.

Transformer backup protection operation causes and treatment

Transformer backup protection reasons are: the high-pressure side of the transformer short circuit. Transformer low-voltage busbar short circuit. Since the failure occurred within the differential protection, differential protection failure. Low line failure,  Voltage stabilizer  tripping, causing a transformer overload tripping. If the over-current protection, found that the voltage drop, shock, arc, sound and so on, to deal with external transformer checks; If timely troubleshooting, you can try to send one, or should be ready to take safety measures to repair; If no problems are found, also may try to send a; transformer differential  air circuit breaker  non-, in addition to external examination, it should also be measured to check the insulation. If the low-pressure outlet failure, line protection tripping, you can manually destroyed fault line switch, power transmission and transformer. If the differential due to a fault occurs within the scope of protection, differential protection failure, the differential protection should be handled.

Troubleshooting substation with transformer

Found the following cases, the emergency disconnect each side of the transformer power supply: Internal strongly inhomogeneous noise and the sound of the spark discharge; conservator or spill-proof tube; casing burst, flashover discharge exaggerating; Oil and gas meter relay do not see the oil level; under normal load conditions, the temperature swells,  electri cenergy meter  the allowable value; If the standby power switch automatically when the power loss in the transformer, check switch is good;  power transformers  the high voltage side of the transformer isolation switch, it is checked if the switch into standby transformer should be good to keep the power supply. If the high voltage transformer fuse breaking work should be put into standby transformer, then opened the work on both sides of the transformer isolation switch, check its associated equipment to determine the cause of the accident.