How to Maintain Vacuum Circuit Breaker?

A breaker which used vacuum as an arc extinction medium is called a vacuum circuit breaker (vcb breaker). In this circuit breaker, the fixed and moving contact is enclosed in a permanently sealed vacuum interrupter. The arc is extinct as the contacts are separated in high vacuum. It is mainly used for medium voltage ranging from 11 kV to 40 kV.

Vacuum circuit breakers are used for switching purposes in high voltage (HV) applications. VCB circuit breakers have a much longer lifespan than conventional circuit breakers and require little maintenance. In this article, we will introduce the routine maintenance of vcb circuit breaker in ATO store.

Daily Maintenance Requirements of Vacuum Circuit Breaker:

• Keep the vcb circuit breaker clean, especially clean the dust of insulators, insulating rods and other insulating parts in time. Dust on the vacuum arc extinguishing insulation shell should be wiped with a clean dry cloth.
• All parts of active friction should be kept with clean lubricating oil, so that the operation mechanism can act flexibly and reduce mechanical wear.
• Wear more serious parts of 11kv vcb breaker to be replaced in time. All fasteners should be inspected regularly to prevent loosening.
• Always observe the color of the vacuum arc extinguishing chamber when the current is on. If there is any doubt, the vacuum degree should be checked. If the vacuum degree does not meet the requirements of the minimum working vacuum degree, it should be replaced in time.
• Often observe the contact stroke, if the deviation from the specified value is too large, should be adjusted in time. The change of contact stroke is the wear amount of the contact in the arc extinguishing chamber, so it must be recorded after each adjustment of contact stroke, and the arc extinguishing chamber should be replaced when the accumulated wear thickness of the contact is reached.
• The overall inspection and adjustment of 33kV vcb in operation should depend on the occasion and frequency of operation. For those whose annual operations do not exceed one fifth of the life of the machine, the inspection shall be conducted at least once a year during the life of the machine. If the number of operations is more frequent, the number of operations between inspections should not exceed one fifth of the mechanical life.
• For the circuit breaker with very frequent operation, the inspection period should be appropriately shortened. Inspection and adjustment items in addition to vacuum degree inspection, opening distance and contact stroke inspection, contact pressure inspection, three-phase synchronous performance inspection, as well as the operating mechanism of each part of the inspection and external electrical connection and insulation inspection, including control power auxiliary contact.

Key Points in Maintenance:

• Insulation. This is one of the simplest maintenance techniques. Insulation maintenance applies to the cleaning of all the insulation surfaces. Any soft cloth like a dry lint-free cloth or dry paper towel can be used to wipe off the dust from the insulation surfaces to ensure their smooth functioning. If wiping is unable to remove dust properly, distilled water or a mild solvent can be used for the purpose of removing dirt and dust. Once wiped, make sure that all the surfaces have completely dried up before placing the circuit breaker in service. Inspect for any damage to the insulation and ensure that all the wires are tightly connected before putting the circuit breaker back in use.
• Lubrication. Proper lubrication is required periodically to ensure the overall smooth and correct functioning of all the parts of a vacuum circuit breaker and vcb maintenance. The gap between relubrication depends on the frequency of the circuit breaker used. Generally, it is suggested to go for relubrication once a year. For lubrication, a drop of light machine oil can be used. After lubrication, the circuit breaker needs to be operated several times manually and electrically so that the oil is absorbed into the parts properly.