Regarding the operation steps of the drop-out fuse, the three-phase operation sequence of the high-voltage drop-out fuse, the power-off operation sequence of the distribution transformer, and the operation of the operator when the drop-out fuse is opened and when the drop-out fuse is pulled and closed are introduced in detail. Precautions at the beginning or end of the type fuse.

1. The three-phase operation sequence of the high-voltage drop-out fuse.

When power cut operation, the middle phase should be pulled first, and then the two side phases. When power is on, the two side phases are first combined, and then the middle phase is combined. The reason for pulling the middle phase first during a power failure is mainly considering that the current when the middle phase is cut off is smaller than that of the side phases (part of the load of the circuit is transferred to the two phases), so the arc is small and there is no danger to the two phases.

When the second-phase (side phase) drop-out fuse is operated, the current is relatively large, and the middle phase is already opened at this time, and the other two drop-out fuses are far apart to prevent the arc from being elongated and causing a short circuit between phases.

When encountering strong winds, the power should be cut in the order of pulling the middle phase first, then the leeward phase, and finally the windward phase.

When power is supplied, the windward phase is first connected, then the back phase is closed, and finally the middle phase is closed, so as to prevent short circuit caused by wind blowing and arc.

2. Operation sequence of power outage and transmission of distribution transformer:

Under normal circumstances, when the power fails, the low-voltage switch on the load side should be opened first, and then the high-voltage drop-out fuse on the power supply side should be opened.

In the case of multiple power supplies, power failure in the above sequence can prevent the transformer from retransmitting power. In the event of a fault, the protection may refuse to operate, prolong the fault removal time and expand the accident.

The power transmission operation step by step from the power supply side can reduce the impact starting current (load), reduce voltage fluctuations, and ensure the safe operation of the equipment. In case of failure, it can be tripped or stopped immediately, which is convenient for inspection, judgment and processing according to the power transmission range.

When the power fails, stop the load side first, and the power failure operation sequence from low voltage to high voltage step by step can prevent the switch from cutting off a large amount of current and reduce the amplitude and frequency of operating overvoltages.

Try to avoid pulling and closing the drop-out fuse with load during operation. If you find that the fuse is wrongly connected with the load during operation, even if it is wrongly closed or even an arc occurs, you are not allowed to open the fuse again.

If the fuse is pulled incorrectly under load, an arc will occur when the moving contact just leaves the fixed contact, and it should be closed immediately to eliminate the arc and avoid the expansion of the accident. (www.dgjs123.com Electrician World) However, if the fuse has been fully opened, it is not allowed to close the fuse by mistake.

For distribution transformers with a capacity of 200 kVA and below, the fuse on the high voltage side is allowed to divide and close the load current.

3. When the operator starts or finishes pulling and closing the drop-out fuse, there must be no impact. The impact will damage the fuse, such as breaking or cracking the insulator, bumping the duckbill, pulling off the operating ring, or breaking. When operating the opening and closing of the drop-out fuse, the staff must not use excessive force or impact to avoid damage to the fuse, and the opening and closing must be in place.

The process of closing the fuse is slow (start)-fast (when the moving contact is close to the static contact)-slow (when the moving contact is close to the end of closing). The process of pulling the fuse is slow (beginning)-fast (when the moving contact is close to the static contact)-slow (when the moving contact is close to the end of the switch). Fast is to prevent electrical short circuits and burn contacts caused by electric arcs, and slow is to prevent operating shocks from causing mechanical damage to the fuse.

4. When opening the drop-out fuse, the operator must use an insulating rod with a suitable voltage level and pass the test, wear insulating shoes, wear insulating gloves, insulating caps and goggles or stand on a dry wooden table with someone Guardianship to ensure personal safety.