Application of the hottest control fuse in switchi

2022-07-24
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The application of control fuse in switching operation

the closing and tripping of high-voltage circuit breaker (hereinafter referred to as switch) is realized according to its own control circuit, and the operating power supply of the control circuit is provided by the control fuse (hereinafter referred to as fuse). Therefore, the control fuse of the control circuit is an indispensable element in the process of closing and tripping of high-voltage switch

the following provisions are made in Article 19 of the current safety work regulations for electric power industry (electrical part of power plants and substations) (hereinafter referred to as the regulations on greater environmental pollution by safety). The power cut-off and switch off operation must be carried out in the order of switch, load side knife switch and bus side knife switch, and the power transmission and switch on sequence is the opposite. Take strict precautions against loaded broach brake. However, the operation of insurance is not regulated. In practice, after the switch is powered off (before), in order to prevent misoperation and consider the safety of maintenance work, the control fuse must be removed to disconnect the power supply of the control circuit

since there is no regulation on the operation of the insurance in the regulation of safety with two backup rollers, there are differences in the practices of each power plant and substation at present, whether to remove (input) the control insurance after the switch operation (before) or after the knife switch operation (before)

in accordance with the provisions of the safety regulations, we use the switch to cut off power: first disconnect the switch, and then open the load side knife switch and the power side knife switch; The operation sequence of power transmission is: first close the knife switch on the power side, the knife switch on the load side, and then close the switch. This operation sequence is to prevent the operator from operating the knife switch at the wrong interval. If the knife switch is opened (closed) with load on the load side of the switch, the switch protection can be used to remove the fault; As for the operation of the knife switch on the power side, since there is already an obvious disconnection point, it will not cause the accident of pulling (closing) the knife switch with load

(1) in case of power failure, remove the control fuse after the switch is disconnected, and then operate the knife switch; During power transmission, after the knife switch operation is completed, the control fuse shall be put into operation for switching operation. This sequence can prevent the operator from pulling (closing) the knife switch with load caused by someone closing the switch by mistake during the knife switch operation. However, it obviously has the disadvantage of becoming the first international high-end aluminum alloy new material enterprise group with the advantages of the whole industrial chain of coal, electricity, aluminum and aluminum intensive processing in China, that is, the switch position indication is in the off position but is not actually disconnected or the switch is not disconnected after maintenance. When the knife switch is operated, if the knife switch is pulled (closed) with load, the switch control insurance is not enabled, and the switch cannot start the protection trip, which will expand the accident. Therefore, this method of operation is not desirable

(2) in case of power failure, remove the control fuse after the knife switch is operated; During power transmission, the control insurance shall be put into operation before the knife switch operation. In this operation mode, as long as the operator can follow the normal operation sequence, even if the switch position indication is in the off position and is not actually disconnected, or the switch is not disconnected after maintenance, and under any unimaginable circumstances, the switch can correctly start the protection trip and remove the fault. The only disadvantage of this operation mode is that when the operator operates the knife switch, if someone closes the switch by mistake, it will cause the accident of pulling (closing) the knife switch with load. However, this kind of accident can be avoided as long as a signboard prohibiting switching on and someone working is hung on the control handle of the switch during the operation of the knife switch

therefore, it is suggested to change article 19 of the safety regulations into that the power cut-off operation must be carried out in the order of switch, load side knife switch, bus side knife switch and removing the switch control fuse. The sequence of power transmission and closing is related to this. Take strict precautions against loaded broach brake

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