High and low voltage distribution knowledge
1, why outdoor bus connector easy fever?
Answer: outdoor bus will often suffer from wind, rain, snow, sun, frozen erosion. All of these can make busbar joint accelerated oxidation, corrosion, the joint has increased contact resistance, temperature rise.
2, the system oscillation occurs the phenomenon?
Answer: the system oscillation phenomenon:
(1) in the substation current, voltage meter and power meter pointer to a periodic swing, such as a contact line, meter swing the most obvious.
(2) from the system oscillation center voltage swing closer, more big, incandescent lights flickering, very obvious.
In 3, DC system in Substation in what role?
Answer: DC system in substation for control, signal, relay protection, automatic device and accident lighting to provide reliable DC power supply. It also provides reliable operation of the power operation. DC system can be * or not, to the transformer substation safe operation plays a vital role, is to ensure the safe operation of substation.
4, what are the internal over voltage?
Answer: Internal Overvoltage is caused to operate, accidents or other causes of system state change suddenly appears from a stable state to another steady state process, in this process may have on the system has dangerous overvoltage. The over voltage is within the system electromagnetic oscillations and accumulation of cause, so called internal over voltage.
5, low voltage AC / DC circuit can share a cable, why?
Answer: can not, because:
(1) share a cable can reduce the DC system insulation level.
(2) if the DC insulation failure, then the DC mixed line will cause a short circuit or protective relay misoperation.
In 6, the circuit breaker target=" _blank" > high voltage breaker closing buffer what role?
Answer: separating brake buffer role is to prevent the spring releases energy generated due to the tremendous impact damage to the circuit breaker components.
Closing buffer role is to prevent the closing impact closing too deep and the damage casing.
7, what is the circuit breaker trip free?
Answer: circuit breakers in the closing process in any moment, if protective action on the tripping circuit, circuit breaker can be * disconnect, this is called free trip. With a free tripping the circuit breaker, can ensure the circuit breaker to the fault, can be quickly disconnected, avoiding the enlargement of the range of accident.
In 8, SF6 gas which has good arc extinguishing performance?
Answer: SF6 gas has the following good performance:
(1) arc column with high electrical conductivity, the arc voltage is very low, less energy arc column.
(2) when the AC current passes zero, SF6 gas dielectric strength recovery fast,100 times faster than air, namely its arcing ability is 100 times higher than air.
(3) SF6( kb0-12c ) gas insulated high strength.
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