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Mechanical key interlocks in power plants

Release time:

2023-07-27 09:18

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This paper lists the application of mechanical key locks in electrical switching operations to avoid mishandling accidents from technical measures.

Mechanical plug-in key interlocking for electrical equipment is a safe operating system, which must be operated in the specified order to prevent human error, otherwise no subsequent operation can be carried out to ensure the safety of personal equipment . The interlocking method is simple, reliable, direct and effective, especially suitable for interlocking between multiple cabinets or doors. Operators are easy to identify and eliminate misoperation. Widely used in power plants, metallurgy and other fields.

In this paper, the power plant dry-type transformer, frequency conversion cabinet, electric precipitator maintenance of power supply outage as an example, from the technical measures to explain how the mechanical key to achieve interlocking operation.

According to the requirements of the electric power operation specification, the dry-type transformer overhaul should first disconnect the low voltage 380V switch, then disconnect the high voltage 6kV switch, then ground the 6kV switch, and finally open the transformer door to carry out the overhaul. Transformer. In this order of operation, mechanical locks are installed on the 380V switchgear, the 6kV switchgear grounding knife and the transformer door, respectively.

During operation, a key can only be removed by disconnecting the 380V circuit breaker. At this time, the 380V circuit breaker is locked in the disconnected state. Take this key to open the earthing knife in the 6kV switchgear (note: the self-locking of the 6kV circuit breaker and earthing knife can be used here). With the earth knife grounded, remove the other key. The earthing knife is locked to earth.

At this point, ensure that the low voltage and high voltage switches are disconnected and grounded. Finally, take out the key to open the transformer door for transformer maintenance. High and low voltage switches can be powered by reverse operation (as shown in Figure 1).

Interlocking operation sequence: close the 380V switch, pull out the key 2a, the cabinet is locked in the state of power failure → close the 6kV switch, use the key 2a to unlock the grounding knife on the 6kV side, the grounding knife is grounded, pull out the key 2B, and the grounding knife is locked in the state of grounding → open the cabinet door of the high-voltage side of the dry-type transformer with the key 2B, and pull out the key 2C → use the key to open the cabinet door on the low-voltage side of the dry-type transformer.2C. After the power is on, the The staff can carry out maintenance on the transformer.

According to the requirements of the electrical switching code, the power-on operation of the inverter cabinet (as shown in Fig. 2) is to make sure that the bypass switch K3 is disconnected before closing the outgoing switch K2, and then to close the incoming switch K1, and finally to supply power to the superior high-voltage switch.

The power-off operation of the inverter cabinet is to disconnect the upper high-voltage switch, then disconnect the incoming cabinet knife switch, and then disconnect the outgoing knife switch.

The power-on operation of the inverter cabinet is to make sure that the inlet and outlet switches are disconnected, the bypass switch is closed and the upper high-voltage switch is closed. The power-off operation of the frequency converter cabinet is to disconnect the upper high-voltage switch first, and then disconnect the bypass switch.

According to the above operational requirements, a mechanical lock is installed on the high-voltage switchgear, and then two mechanical locks are installed on the incoming switch, the outgoing switch and the bypass switch. One lock realises switch opening, the other lock realises switch closing

When the inverter cabinet is powered off, first disconnect the high-voltage switch, pull out the locking key of the high-voltage switch, and the high-voltage switch is locked in the power-off state.


Use this key to unlock the inlet switch, disconnect the inlet switch, lock the switch, pull out the key, and the inlet switch locks in the off state. Use the key withdrawn to unlock the socket switch, disconnect the socket switch, pull out the key and the socket switch locks in the off state.

With this key, the bypass cabinet knife gate can be unlocked and powered up, and then another key on the bypass knife gate can be pulled out to supply power to the high-voltage switch, so as to realise the conversion of the fan from the inverter mode to the industrial frequency mode.

The primary fan B1 is normally in the frequency conversion working state: K1 and K2 knife switches are closed and K3 knife switch is open. Frequency power inverter bypass interlock operation sequence:

Keywords:

Huahe lock making, Huahe lock industry, Guizhou intelligent lock, Guizhou padlock, intelligent lock, padlock

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