How to deal with the fault of high and low voltage switch cabinet in high and low voltage distribution cabinet
Closing faults can be divided into electrical faults and mechanical faults. There are two closing methods: manual and electric. Manual failure to close is generally a mechanical failure. It is an electrical fault that it can be closed manually and cannot be closed electrically. There are maintenance actions, protection faults, electrical interlocking, auxiliary switch faults, etc. when the high-voltage switchgear cannot be closed electrically.
1. Maintenance action: The maintenance action has been analyzed to trip the switch. Before the switch is powered on, the line has a fault maintenance loop to make the anti-jump relay work. The switch trips immediately after closing. Even if the transfer switch is still in the closing position, the switch will not close again and jump one after another. In addition, regarding the load switch+fuse cabinet, if the primary fuse burns out, it can also cause the switch to fail to close.
2. Protection against failure: Now, five protection functions are set in the high-voltage cabinet. For the central cabinet, it is required that the switch is not in the running orientation or the experimental orientation and cannot be closed. That is to say, the azimuth switch is not closed, and the motor cannot be closed. This kind of fault is often encountered in the closing process. At this moment, the running orientation light or the experimental orientation light is not on. Move the switch handcart slightly to close the limit switch to send electricity. If the offset interval of the limit switch is too large, it should be adjusted. Regarding the ring network cabinet, check whether the cabinet door is closed and whether the grounding switch is in the opening position.
3. Electrical interlock failure: Some electrical interlocks are set in the high-voltage system for the reliable operation of the system. For example, in the single-bus subsection system with two-way power supply incoming lines, it is required that only two of the three switches, the two-way incoming line cabinet and the bus coupler cabinet, can be combined. If all three units are closed, there will be the risk of reverse power transmission. Moreover, the short-circuit parameters change, and the short-circuit current in parallel operation increases. The way of interlocking circuits is shown in Figure 4. The interlocking circuit of the incoming cabinet is connected in series with the normally closed contact of the bus coupler cabinet, which requires that the incoming cabinet can be closed when the bus coupler cabinet is open. The interlock circuit of the bus coupler is connected in series with one normally open and one normally closed of two incoming cabinets respectively and then in parallel. In this way, it can be ensured that the bus coupler can only send power when one of the two incoming cabinets is closed and the other is opened. When the high-voltage cabinet can’t be closed electrically, the first thing to consider is whether there is an electric interlock, and it can’t be closed manually blindly. Electrical interlocking faults are generally improper operation and can not meet the closing requirements. For example, although the inlet cabinet of the bus coupler is divided into one and one, the handcart in the opening cabinet is pulled out and the plug is not plugged in. If the interlock circuit breaks down, you can use a multimeter to check the fault location.
It is simple and convenient to use red and green lights to judge the fault of auxiliary switch, but it is not very reliable. Be able to check with a multimeter. The way to overhaul the auxiliary switch is to adjust the viewpoint of the fixed flange and the length of the connecting rod of the auxiliary switch.
4. Open circuit fault of the control loop: the control switch is damaged and the line is disconnected in the control loop, which makes the closing coil unable to get electricity. At this time, the closing coil has no sound of action. There is no voltage across the measuring coil. The check method is to check the open point with a multimeter.
5. Fault of closing coil: Burning of closing coil is a short circuit fault. At this time, there are odors, smoking, and safe melting. The closing coil is planned to work for a short time, and the power-on time cannot be too long. After the failure of closing, the reasons should be found in time, and repeated closing should not be repeated. In particular, the closing coil of CD-type electromagnetic operation organization is easy to burn out because of the large passing current and repeated closing.