The concept of five defenses
1. Prevent closing the isolation switch with load.
2. Prevent accidental opening and closing of circuit breakers.
3. Prevent the grounding switch from closing with load.
4. Prevent the load from being sent out when the grounding switch is closed.
5. Prevent accidental entry into the charged area.
The five prevention lock refers to the implementation of the above five prevention measures. The installed lock needs to cooperate with the microcomputer five prevention system or achieve the functions of the five prevention through strict personnel five prevention operation procedures.
The "five electrical precautions" of high-voltage switchgear are important measures to ensure the safe operation of the power grid, ensure the safety of equipment and personnel, and prevent misoperation. GB3906-1991 "3-35kV AC Metal Enclosed Switchgear" specifies this.
The above five measures to prevent electrical misoperation are collectively referred to as the "Five Precautions". The "five prevention" devices can generally be divided into three categories: mechanical, electrical, and comprehensive. At present, there are various types of high-voltage switchgear on the market, and most of them have complete shaft interlocking methods.
1. After the vacuum circuit breaker handcart in the high-voltage switchgear is closed in the test position, the handcart circuit breaker cannot enter the working position (to prevent load closing)
2. When the grounding switch in the high-voltage switchgear is in the closed position, the handcart circuit breaker cannot be closed (to prevent closing with grounding wire)
3. When the vacuum circuit breaker in the high-voltage switchgear is closed, the back door of the panel cabinet is locked with the machine on the grounding switch (to prevent accidental entry into the live section)
4. The vacuum circuit breaker in the high-voltage switchgear is in a closed state during operation, and the closing ground switch cannot be put into operation (to prevent hooking or connecting the ground wire when energized)
5. When the vacuum circuit breaker in the high-voltage switchgear is closed and running, it is not allowed to exit the working position of the handcart circuit breaker (to prevent pulling the knife switch with load)
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