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The electrical "five defenses"

The electrical "five defenses"
Issue Time:2018-10-31

Basic definition: Five defenses usually refer to the abbreviation of five kinds of anti-misoperation functions for electrical equipment to ensure personal safety. It is one of the important measures for electric power safety.

First, what is the electrical "five defenses"? The electrical "five defenses" are:

1. Prevent the separation and closing of the switch with load. (The circuit breaker, load switch, and contactor cannot be operated in the closed state.)

2. Prevent mis-sorting, mismatching circuit breakers, load switches, and contactors. (Only the operation command can correspond to the operation device to operate on the operated device)

3. Close the circuit breaker and load switch when the grounding switch is in the closed position. (Only when the grounding switch is in the open state, the disconnector or the handcart can be moved to the working position to operate the circuit breaker and the load switch is closed)

4. Prevent misalignment of the grounding switch when it is energized. (Only when the circuit breaker is opened, the disconnector or the handcart can be operated to retreat from the working position to the test position to close the grounding switch)

5. Prevent accidental entry into the live compartment. (The door can only be opened when the compartment is not energized)

Second, the concept of "five defenses":

1, anti-load separation switch

2, prevent mis-separation, mis-circuit breaker

3, anti-loading switch closing earthing switch

4. When the anti-grounding switch is closed, the load is sent.

5, anti-missing into the charging interval

Five anti-locking is to implement the above five precautions, and the installed locks, in order to achieve the five-proof function, also need to cooperate with the microcomputer five-proof system or through strict personnel five-proof operation rules.

Third, what is the "five defenses" of the high voltage cabinet?

The "interlocking" of high-voltage switchgear is an important measure to ensure the safe operation of the power grid, ensure equipment and personal safety, and prevent misoperation. GB3906--1991 "3 ~ 35 kV AC metal-enclosed switchgear" has clearly defined this. Generally, the "interlock" is described as: preventing mis-separation and mis-closing of the circuit breaker; preventing the separation and closing of the load switch; preventing the grounding (closing) grounding wire (grounding switch); preventing the grounding wire (switch) from closing; Prevent accidental entry into the charging interval. The above five items to prevent electrical misuse are referred to as “five defenses”.

Fourth, how to achieve "five defenses"?

1. Prevent accidental entry into the charging interval. After the working trolley is shaken to the “Isolation/Experimental” position, the grounded metal partition automatically falls to cover the live static contact part to prevent the personnel entering the cabinet from contacting the live part. After the switch grounding knife is closed, the mechanical interlock of the rear door allows the door to be opened.

2. Preventing the load from being split into one or two contacts: When the contactor is in the closed state, the connecting rod on the mechanical interlocking baffle propulsion mechanism that is interlocked with the contactor makes the propeller mechanism spiral unable to rotate. When the load is applied, it is impossible to separate the primary and secondary contacts.

3. Prevent live grounding: When the trolley enters the working position, the propeller of the propulsion machinery is pressed against the curtain device of the grounding switch closing mechanism, so that the curtain cannot be opened, and the grounding switch cannot be closed.

4. Prevent the grounding of the grounding switch: When the grounding knife is closed, the shutter device baffle will prevent the trolley from entering the cabinet, thus avoiding the possibility of the contactor in the grounded state.

5, to prevent circuit breakers from misclassification: the operating personnel always keep in mind the procedures and operate according to the operation ticket.

Fifth, what do the 6kV and above malignant misuse accidents mean?

6kV and above power supply equipment, with load mis-pull (closed) isolating switch, live hanging (closed) grounding wire (grounding knife), with grounding wire (grounding knife) combined with circuit breaker (isolation switch).

                          By: JUCRO Electric (Focus on Vacuum Interrupter, Vacuum circuit breaker, Vacuum contactor and Switchgear)

                                                                                                                                                2018.9.10

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