ABB 07DC91 GJR5251400R0202 controller 31 I/O unit

Description

07DC91 fault phenomenon: On July 7, 2015, a substation monitoring background light plate “Non electric quantity protection alarm of No. 3 main transformer body” and “light gas alarm of phase C body”.
Cause of fault: check the oil level of the observation window of the gas relay of the main transformer of phase C of No. 3 main transformer on site (the gas volume exceeds 300ml, and the setting value of the light gas alarm of 07DC91 is 270 ± 10ml) (the normal phase of phase A and B is full oil level). According to the inspection results and the discussion at the special meeting, it is determined that the fault is caused by metal foreign matters. According to the position and shape of the foreign matters taken out on site, it is judged that the metal foreign matters were brought in during the non manufacturing process. Since the monitoring equipment cannot cover the whole manufacturing process, it is impossible to judge the time period when foreign matters are brought into the body.
Fault handling: the fault transformer can no longer operate, and it is moved into the standby phase. The on-site repair scheme is adopted for the fault transformer. A maintenance workshop is built in the substation, which is repaired by the manufacturer’s personnel and stored in the substation as a spare phase.

2、 Light gas alarm 2 of a substation
Fault phenomenon: on September 30, 2015, the monitoring background of 07DC91 substation reported “Phase C pressure sudden change alarm signal of # 2 main transformer”, “heavy gas trip signal” and “light gas alarm signal”; The electrical quantity protection does not act.
Cause of failure: There was a problem in communication between the design institute and the manufacturer, which caused the force on the terminal at the top of the bushing to exceed the limit value; The casing itself has weaknesses in sealing design; There is a negative pressure area on the top of the casing current carrying duct, which is very easy to cause air or water to be sucked into the casing after the seal failure. The maximum horizontal deviation between the T-contact of the lead wire and the high-voltage bushing is 5.61m. The terminal on the top of the high-voltage bushing has been subjected to the side tension for a long time, causing the terminal and the cover plate to be skewed and deformed. The sealing function of the cover plate has failed. Under the effect of the negative pressure on the top of the bushing, air and water are drawn into the bushing guide rod along the gap of the cover plate and flow into the transformer along the inside of the guide rod, causing the internal discharge of the high-voltage winding.
Fault handling: the fault transformer can no longer operate, and it is moved into the standby phase. The on-site repair plan is adopted for the faulty transformer. A maintenance workshop is built in the substation, which will be stored as a spare phase in the substation after the repair work is completed in 2016.
3、 Light gas alarm 3 of a substation
Fault phenomenon: On June 18, 2018, the light gas alarm of phase A of main transformer of substation # 1 was given.
Cause of fault: The results of oil and gas extraction detection of the transformer are non combustible gas, and the data of oil extraction results are within the normal range. After exhausting the gas relay on that day, the signal will reset at that time. After that, the gas collection of the gas relay was tracked for a long time, and no new gas was accumulated, which was judged to be caused by the long-term accumulation of air.
4、 Light gas alarm 4 of a substation
Fault phenomenon: Phase C light gas alarm occurs during the commissioning of No. 3 main transformer.
Cause of fault: the oil flow relay of the main transformer leaked oil, and the construction unit did not drain the gas after replacement. Through inspection, the transformer has no acetylene.
Fault handling: exhaust the gas in the transformer.
5、 Light gas alarm 5 of a substation
Fault phenomenon: At 06:24:55 on November 20, 2018, the OWS background of a converter station reported that “light gas alarm of phase B converter body on one side occurred”, at 06:40:57, “heavy gas protection of phase B converter on one side occurred”, and the three phases of 01B 02B converter switch tripped.
Fault cause: the oil conservator capsule is broken. After the oil is injected into the oil conservator capsule, the temperature drops suddenly in the weather, the oil containing capsule sinks to the bottom of the conservator, blocks the oil pipe, and there is gas in the pipeline, causing the gas exchange flow to act. The reason for capsule damage is that the transformer is in long-term standby, and the low temperature accelerates capsule aging.
Fault treatment: the capsule of converter transformer oil conservator was inspected on site, and it was found that there was a crack in the capsule, and most of the oil in the conservator had entered the capsule. After the capsule was replaced, the converter resumed operation.
6、 Light gas alarm 6 of a substation
Fault phenomenon: On January 2, 2017, DC bipolar cold standby of an electric power company, 20:37, the light gas alarm of the 1YYC converter in the substation pole. 20: 42 engines tripped due to heavy gas.
Cause of fault: during on-site inspection, it was found that the circulating oil pump of the fourth group of coolers of pole 1 Y/Y C phase converter had oil leakage, so the power supply of the submersible pump was disconnected and the valves at both ends of the submersible pump were closed, and the oil leakage stopped. According to the preliminary analysis, the reason is that the materials of the bolts and the end cover flanges of the pump body are poor. After a long period of operation, the cover plates and flanges of the pump body are severely rusted, and the bolts are rusted, resulting in the pump body slipping and large oil leakage.
Troubleshooting: replace pole 1, 4 sets of submersible pumps with YYC phase converter, replace the converter for oil supplement, and conduct maintenance test. The 52 submersible pumps of the other 13 converters (including 2 standby) were replaced or the bolt structure was changed simultaneously.

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