Protection device having functions of automatic control, energy moving and degradation self-separation for vacuum arc extinguish chamber

Abstract

The invention relates to a protection device having functions of automatic control, energy moving and degradation self-separation for a vacuum arc extinguish chamber. The protection device comprises an automatic degradation off-line device TQ and an energy-moving component R1 which are arranged in series; the two ends of the energy-moving component R1 are connected with a resistor-capacitor (R-C) loop in parallel; a resistor R and a capacitor C in the R-C loop are connected in series; the automatic degradation off-line device TQ comprises a shell; a fuse is arranged in the shell; quartz sand is filled in the shell; a cavity is formed in the middle of the upper part of the shell; a post-degradation off-line indicator and a pre-compaction spring are arranged in the cavity and sealed in the cavity; the lower end of the fuse is connected with a second electrode; the upper end of the fuse passes through the pre-compaction spring and then is connected with the post-degradation off-line indicator; the upper part of the shell is provided with a first electrode; and a lead line of the first electrode is buried in the quartz sand. By the protection device, the reignition rate of a vacuum breaker can be reduced, and the reignition overvoltage, the shut-off overvoltage and the overvoltage during simultaneous cut-off of three phases can be reduced, so that the arc extinguish chamber of the vacuum breaker can be protected, and other electrical equipment can be also protected.

Description

technical field [0001] The invention relates to a protection device for power switchgear, more specifically to provide a protection device for limiting the operating overvoltage of a vacuum circuit breaker and restarting of a vacuum interrupter in a medium-voltage power system below 35kV. technical background [0002] Due to the advantages of small maintenance workload, large breaking capacity, long service life and suitable for frequent operation, vacuum circuit breakers have gradually replaced other types of switches in power systems and have been widely used. However, it has also aroused great concern in practical applications, because vacuum circuit breakers will generate operating overvoltages when they are cut off, reignited or three-phase disconnected, which will cause insulation breakdown of motors and other equipment, and flashover between phases, seriously threatening To the insulation of electrical equipment such as transformers, motors, capacitors, and reactors, ...

AI Technical Summary

Problems solved by technology

Usually, the main ways to solve the above problems are as follows: First, the various lightning arresters and three-phase combined overvoltage protectors that are widely used at present all use the residual voltage of the zinc oxide resistor to limit the amplitude of the overvoltage, but only the amplitude is limited. The frequency cannot be limited, and the electrical equipment cannot be effectively protected. Moreover, due to the response speed of zinc oxide, the steeper the wave head of the overvoltage, the higher the residual voltage of the zinc oxide valve plate (the residual voltage under the steep wave impulse current is higher than the operation impulse current is 20~35% higher), which makes it extremely difficult to cooperate with the withstand voltage of the motor. The cut-off and re-ignition overvoltage is similar to a steep wave, and the wave head time is extremely short, less than 1μS, which will make each This kind of lightning arrester and three-phase combined overvoltage protector are difficult to effectively protect electrical equipment under high-steep overvoltage; the second is to improve the contact structure and increase the vacuum degree of the arc extinguishing chamber, so that the dynamic and static contacts of the arc extinguishing chamber are just separated. When the withstand voltage level is lower than the recovery voltage between the two contacts

Therefore, people usually take measures such as increasing the creepage distance on the surface of the circuit breaker. Practice shows that: the method of "reinforced insulation" is adopted inside and outside the vacuum interrupter, and the restrike rate and cavity The external flashover rate is still high, and accidents occur from time to time; all of the above schemes have a series of technical problems such as excessive residual voltage, unreasonable protection, unstable protection, and automatic exit function without deterioration, which bury hidden dangers for the safe operation of the power grid

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