Electric Encyclopedia: Knowledge of high and low voltage power distribution and answers

1, high-voltage circuit breaker opening and closing buffer play what role?

A: The function of the opening damper is to prevent the components of the circuit breaker from damaging due to the huge impact generated when the spring releases energy.

The function of the closing damper is to prevent the closing force and make the closing too deep and damage the casing.

2, what is the circuit breaker free tripping?

A: The circuit breaker in the closing process at any time, if the protective action connected to the trip circuit, the circuit breaker can be disconnected, which is called free tripping. Breaker with free tripping, circuit breakers can ensure short circuit fault, can be quickly disconnected, to avoid expanding the scope of the accident.

3, SF6 gas what good arc performance?

A: SF6 gas has the following good performance:

(1) arc column conductivity, arc voltage is very low arc column energy is smaller.

(2) When AC current crosses zero, dielectric strength of SF6 gas recovers fast, about 100 times faster than air, that is, its arc extinguishing ability is 100 times higher than that of air.

(3) SF6 gas insulation strength higher.

4, Why outdoor bus connector easy to heat?

A: The outdoor bus should always be the wind, rain, snow, sun, ice and other erosion. These can promote busbar joints to accelerate oxidation, corrosion, making contact resistance increases, the temperature increases.

5, the system oscillation what phenomenon?

A: The system oscillation phenomenon:

(1) The current in the substation, voltmeter and power meter pointer cyclically swinging, if the contact line, the most obvious swing meter.

(2) The closer to the oscillation center of the system, the larger the voltage swing, the incandescent light flickering suddenly and obviously.

6, DC system in the substation in what role?

A: The DC system in the substation for the control, signal, relay protection, automatic devices and accident lighting to provide * DC power supply. It also provides power for operation. DC system can be or not, the safe operation of the substation plays a crucial role, is the guarantee of substation safe operation.

7, what is the internal over-voltage?

A: The internal overvoltage is caused by sudden changes in the state of the system due to operation, accident or other reasons. There will be a transition from one steady state to another stable state during which the system may be dangerous overvoltage . These overvoltages are caused by the oscillation and accumulation of electromagnetic energy in the system, so called internal overvoltage.

8, low-voltage AC-DC circuit can share a cable, why?

A: No, because:

(1) share a cable can reduce the insulation of the DC system.

(2) If the DC insulation is damaged, the DC mixed line will cause short circuit or relay protection misoperation.

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