How to prevent insulation problems of ZW32 vacuum circuit breaker?
Common faults of vacuum circuit breakers are mainly divided into two aspects: electrical circuit faults and mechanical faults. The main problems include air leakage in the vacuum arc extinguishing chamber, insulation failure, failure to operate and malfunction, and different stages of branch gates. How to prevent insulation problems of ZW32 vacuum circuit breaker?
The vacuum circuit breaker is characterized by arc extinguishing in vacuum, but it does not work under any vacuum degree. It has good insulation and arc extinguishing functions only within the vacuum degree range. The internal vacuum in a vacuum switch is usually in the range of 6.5x10-1.3x10 Pa. Differences in vacuum interrupters, dynamic and static contact structures, shielding cover sealing, shell materials, bellows materials and processing methods will all affect the performance of the vacuum interrupter.
As the use time of the vacuum arc interrupter increases and the number of interruptions increases, its vacuum degree may also gradually decrease. If it drops to a certain level, its interruption capacity and pressure resistance level will be affected. The contacts of vacuum circuit breakers are mostly of a butt-jointed structure, which may produce varying degrees of rebound during branch operation, regardless of whether the opening rebound or the platform gate rebound will cause harm to the operation. The impact speed and impact force of the branch gate are large and the rebound may cause the deformation of the contacts and conductive rods, or even cracks. The rebound may cause the bellows to experience forced vibration or cracks, causing air leakage in the arc extinguishing chamber.
The vacuum circuit breaker interrupts the current and extinguishes the arc in the vacuum bubble, but the vacuum circuit breaker itself does not have a device for qualitatively and quantitatively monitoring the characteristics of the vacuum degree, so the vacuum degree decrease fault is a hidden fault, and its risk level is much greater than the explicit fault. The decrease in vacuum degree will seriously affect the ability of the vacuum circuit breaker to interrupt overcurrent, and cause the service life of the circuit breaker to decrease sharply. In severe cases, it may cause the switch to explode.
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During the use of the vacuum circuit breaker, the vacuum degree in the arc extinguishing chamber tube must be checked regularly. The current inspection methods are:
1. The glass-shell vacuum arc extinguishing chamber can be visually inspected regularly. Normally, the surface color of the internal shielding cover and other components should be very bright, and emit light blue arc light when the current is interrupted. When the vacuum degree drops severely, the internal color will become gray, and a dark red arc will be emitted when the current is interrupted.
2. Conduct a power frequency withstand voltage test (42KV) regularly (about 3 years). When the dynamic and static contacts maintain the rated opening distance, if the I-frequency withstand voltage is not lower than the rated I-frequency withstand voltage, it means that the vacuum degree meets the application requirements. If during the voltage boosting process, continuous breakdown or glow discharge occurs inside the vacuum interrupter, it means that the vacuum degree of the vacuum interrupter has seriously decreased and it can no longer be used.
The prevention of insulation accidents mainly starts from the following aspects: First, when selecting a vacuum circuit breaker, consider the use environment and daily maintenance and repair conditions, and choose products with reliable quality. Second, the tooling technology is in place during the installation, debugging, and maintenance processes to avoid external force damage to the insulator caused by the movement of the mechanism during operation. Third, the environment during operation is fully guaranteed to reduce the impact of dust, moisture, etc. on the equipment; the maintenance cycle is shortened, and the insulating part of the switch, including the insulating tie rod, is regularly cleaned and visually inspected as necessary. Fourth, the insulation should be tested regularly according to procedures and specifications. In addition, strengthening insulation life prediction is of great significance to reducing insulation accidents.
