Common fault analysis of the hottest 6kV oil less

Analysis of common faults of 6kV oil less switch and vacuum switch

among the common faults of the switch, the faults of opening coil and closing coil account for more than 90% of the switch faults. The 6 kV distribution system of Zhujiang Power Plant adopts the oil less switch and vacuum switch produced by Tianshui Changcheng switchgear, and the operating mechanism is equipped with CD10. The common faults of the opening and closing coils are analyzed and the corresponding specific measures are put forward for the reference of peers

1 cause of burnout of opening coil

1 Together with the previously released GB 4806.2 pacifier, GB 31603 general hygiene specification for production and GB 31604.1 general rule for migration experiment, 1. The auxiliary switch contact of opening control circuit is improperly used

the opening control circuit is connected with a pair of time-delay dynamic closing contacts. The purpose of this time-delay is to ensure that the circuit breaker can complete free tripping in case of a 10mm short circuit fault from the valve hole diameter during closing. However, when the closing time of the circuit breaker switch is very short, which is far less than the opening time of the circuit breaker, and the circuit breaker has been closed in place before it has time to trip, at this time, the delay effect of the delay contact of the opening control circuit will lose its significance. On the contrary, during the opening process of the time-delay contact, due to the small insulation gap between the dynamic and static contacts of the auxiliary switch, the phenomenon of arcing often occurs. Frequent arcing over time causes the contact of the auxiliary switch to burn out, and then causes the opening coil to burn out

1.2 the position of the opening and closing state of the auxiliary switch is not adjusted properly

in the opening and closing state of the circuit breaker, the auxiliary switch should be adjusted to make its indication within the marked range. However, the initial state of the opening and closing of the circuit breaker will be changed when the opening distance, over travel and other parameters of the circuit breaker are actually adjusted, and the initial state of the opening and closing position of the auxiliary switch has not been adjusted accordingly, It will cause the auxiliary switch to fail to switch the opening and closing circuit normally and burn the opening coil

1.3 the auxiliary switch crank arm screw is loose

because the vibration force is relatively large when the switch is normally opened and closed, long-term switch opening and closing will cause the auxiliary switch crank arm screw to be loose, so that the auxiliary switch cannot be switched normally and accurately, resulting in the burning of the switch opening coil

1.4 mechanical failure of opening electromagnet

loose coil causes displacement of electromagnet core when the switch is opened, which makes the iron core jam and causes coil burnout

1.5 switch refused to open

when the control circuit is normal, the failure of switch refused to open is the problem of four-bar linkage, and the dead point is not adjusted properly, so that the force of switch opening iron core ejector rod cannot make the mechanism trip in time, overload the coil, and cause the opening coil to burn out

2 measures to prevent the opening coil from burning out

(1) change the delayed dynamic closing contact of the opening circuit to a pair of ordinary normally open contacts, often check the contact of the auxiliary switch and stretch the rubber, do not need a lot of force to the crank screw of the auxiliary switch, and correctly adjust the position of the auxiliary switch to make the auxiliary switch and the opening and closing position of the switch cooperate correctly and effectively

(2) fix the opening coil, and often check whether the iron core of the opening coil is jammed

(3) correctly adjust the four-bar mechanism of the switch, and often check whether the free tripping of the switch is normal and whether the low-voltage action test of the switch meets the requirements