Grounding treatment of the hottest DC system

2022-07-23
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DC system grounding treatment

a) the alarm bell rings and the DC fault light plate is on

b) the integrated monitoring device for voltage insulation of group I DC bus or group II DC bus of DC distribution board gives an alarm

b. treatment:

a) determine the group and polarity of the grounding bus according to the alarm of the integrated monitoring device for voltage insulation of the upstream bus of the electromagnet

b) select the grounding point according to the following procedures according to the current equipment maintenance conditions, climate conditions and equipment defects:

⑴ test pull the temporary power supply connected by the maintenance personnel

⑵ contact DC users of machine, furnace, fuel oil, chemistry, etc. to inquire whether there are equipment startup, shutdown and abnormal conditions for searching

⑶ the power DC load shall be selected by the instantaneous stop method in the order of outdoor first and then indoor. For power loads such as DC oil pump, the shift chief operator must inform the operator to take necessary measures and obtain clear permission. The motor can be carried out only after it is checked that it is not in operation. It can be recovered quickly after being pulled off, and the shift chief operator shall be reported to inform the operator

⑷ select the DC load for operation, and adopt the transfer method, that is, first adjust the voltage of two groups of buses in the DC system to be consistent, push the bus coupler switch, and then switch a certain load on the DC bus to the point that even people with one point of experimental basis do not have a non grounding bus (push the disconnecting point switch of the power supply ring, and then open the power supply switch of the power supply ring connected to the grounding bus); After that, jc/t547 ⑵ 005 ceramic tile adhesive opened the bus coupler knife switch to see whether the grounding was transferred to another bus. If it was transferred, the instantaneous stop method was used to stop each branch of the power supply ring load one by one until the fault point was found

⑷ when selecting the operating DC load, the operating DC power supply of the main control building shall generally be the last choice, and the control and signal power supply of the ring power supply shall not be placed on different buses for a long time

⑥ before the DC operation power supply of the equipment is stopped immediately, the relevant personnel on duty shall be contacted first to avoid misoperation of the equipment. During the selection process, in case of any fault, the power supply shall be restored in time

⑺ when 8 is selected for all DC loads and 99 groups of test data are stored and the grounding point is still not found, check the battery, floating silicon, flash device, integrated voltage insulation monitoring device and DC bus itself. At this time, it can be selected by instantly opening the equipment outlet knife switch and removing the DC fuse. If the grounding still cannot be eliminated, the DC bus shall be grounded by itself. After confirmation, necessary safety and technical measures shall be taken to cut off the fault bus and the maintenance team shall handle it

8 after DC grounding, the grounding point must be found as soon as possible and eliminated. It is not allowed to operate for a long time after one point grounding, so as to avoid maloperation or refusal of the protection device after the second point grounding

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