Checking the vacuum degree of a vacuum circuit breaker is a key step to ensure its reliable arc extinguishing and insulation performance. The following are common inspection methods and steps:
1. Appearance inspection
Observe the arc extinguishing chamber: Check whether the vacuum arc extinguishing chamber has cracks, damage or oxidation of internal metal parts (such as abnormal color of the shielding cover, whitening or metal deposition).
Sealing inspection: Confirm that there are no signs of leakage at the connection between the arc extinguishing chamber and the flange (such as oil stains, dust accumulation, etc.).
Power frequency withstand voltage test
Principle: Verify whether the vacuum degree meets the insulation requirements by applying high voltage. If the vacuum degree decreases, internal breakdown may occur.
Steps:
Disconnect the circuit breaker power supply and ground discharge.
Apply the rated power frequency withstand voltage between the breaks (such as 42kV for 10kV circuit breakers, usually for 1 minute).
If no breakdown or flashover occurs, the vacuum degree is qualified; if breakdown occurs, the arc extinguishing chamber needs to be replaced.
Note: Professional equipment (high-voltage test transformer) is required and it must be operated by qualified personnel.
4. Vacuum tester (magnetron discharge method)
Principle: Use magnetic field to stimulate the ionization of residual gas in the arc extinguishing chamber, and indirectly judge the vacuum degree by measuring the ionization current.
Apply pulse magnetic field and high voltage to measure the discharge current.
Compare the vacuum value displayed by the instrument with the standard value (such as the qualified range is usually 10⁻⁴～10⁻⁶ Pa).
Advantages: quantitative measurement, high accuracy, suitable for regular inspection.
5. Contact resistance measurement
Indirect judgment: A decrease in vacuum may cause contact oxidation and increase contact resistance.
Method: Use a micro-ohmmeter to measure the resistance between the moving and static contacts. If the resistance increases abnormally (compared with the factory value or historical data), the vacuum degree needs to be further checked.
6. Infrared thermal imaging or ultrasonic testing (auxiliary means)
Infrared testing: Insufficient vacuum may cause local overheating.
Ultrasonic testing: Internal discharge will generate sound wave signals in a specific frequency band.
7. Precautions
Safety first: Make sure the circuit breaker is powered off and grounded before operation, and follow the high-voltage test safety regulations to operate.
Regular testing: It is recommended to combine preventive testing (such as once a year) or overhaul.
Replacement standard: If the vacuum is lower than 10⁻² Pa or the withstand voltage test fails, the arc extinguishing chamber needs to be replaced (not repairable).
Environmental factors: Avoid testing in humid and dirty environments to prevent misjudgment.
Comprehensive judgment: Combine multiple parameters such as appearance and contact resistance to improve diagnostic accuracy.
Professional support: If there is no special equipment or operating experience, it is recommended to contact the manufacturer or professional testing agency for testing.
ZN28K-12 Vacuum Circuit Breaker produced by Shaanxi West Power Tongzhong Electrical Co., Ltd. is a three-phase AC 50Hz, rated voltage 12kV indoor switching device component. It is primarily installed in metal-enclosed armored switchgear and is used for the control and protection of electrical facilities in industrial and mining enterprises, power plants, and substations. It is suitable for frequent operation environments.
ZN28K-12 Vacuum Circuit Breaker has many advantages:
1.Reliable Performance
Utilizes vacuum arc extinguishing technology, offering strong arc extinguishing capability, the ability to withstand high short-circuit currents, stable breaking performance, and long electrical and mechanical lifespans.
2.Convenient Operation
Can be installed and used independently or integrated into fixed switchgear or box-type switchgear. The operating mechanism is flexible, enabling both electric and manual operation.
3.Easy Maintenance
Features a simple structure with fewer components, eliminating the need for regular replacement of insulating oil, thereby reducing maintenance workload and costs.
Shaanxi West Power Tongzhong Electrical Co., Ltd.:
Ms.Grace Liu (Director of Sales Department)Tel: +86 917 3661109 Fax: +86 917 6739416
Email :xdtz04@westpowerelectric.com
Mobile: +86 18091765882(WhatsApp/Wechat/skype )
Website:https://www.xdtzelectrical.com
