Tests of Vacuum Circuit Breaker
Some of the test perform of the Vacuum Circuit Breaker are:
- Contact Resistance Test
- High Potential Testing
Contact Resistance Test
A contact resistance test using a micro-ohmmeter, where the resistance is measured and documented. The obtained result is then compared to either the design specifications or the average values of other Vacuum Interrupters within the same operation. Contact resistance testing, commonly referred to as Ductor testing, involves assessing the resistance in electrical connections, including terminations, joints, connectors, busbar sections, and cable connections. These assessments apply to connections between any two conductors, such as cable links or busbar sections. The instrument employed for conducting the Ductor test is called an Ohmmeter, also known as a Ductor tester due to its dedicated function.
Ductor testers come in various variants, including Micro, Mega, and Milli-Ohmmeters, as well as static resistance testers or DLRO, which stands for Digital Low Resistance Ohm Meter. These instruments are crucial for measuring resistance in diverse applications within the realm of electrical testing.
High Potential Testing
The open contacts of the vacuum interrupter (VI) undergo a high potential voltage test, where the voltage is incrementally raised to the specified test value, and any resulting leakage current is measured. Factory testing can utilize either AC or DC high-potential test sets, and various portable test sets from manufacturers are accessible for conducting high-potential tests on open vacuum interrupters.
The high potential test is designed to ascertain whether a bus bar can endure its specified withstand voltage once installed on-site or if it is prone to breakdown. Additionally, it aims to evaluate the integrity of the vacuum bottle, measure leakage current, and assess insulation between the circuit breaker (CB) and the ground. The essential testing equipment for conducting a high potential test includes an AC high-voltage injection machine (100KV, 60HZ), a Megger 5KV DC supply, and tools for mechanical and visual inspection.
During the test, it is crucial to verify the adequate clearance (distance) between the circuit test ends and other grounded objects, as well as other phases not under test. Additionally, attention must be given to maintaining sufficient clearance with other electrical equipment to prevent potential flashovers. These precautionary measures contribute to the reliability and safety of the high potential testing process.
What is Vacuum Circuit Breaker?
A vacuum circuit breaker is a type of breaker that utilizes a vacuum as the medium to extinguish electrical arcs. Within this circuit breaker, there is a vacuum interrupter that houses the stationary and mobile contacts in a permanently sealed enclosure. When the contacts are separated in a high vacuum environment, the electrical arc is effectively extinguished. As an illustration, when the contacts of a circuit breaker are opened within a vacuum environment, the interruption takes place precisely at the moment of the initial current reaching zero. This results in the dielectric strength between the contacts rapidly increasing at a rate thousands of times greater than what is achieved with alternative types of circuit breakers.
Table of Content
- Vacuum Circuit Breaker
- Types
- Construction
- Working Principle
- Working
- Tests
- Vacuum Circuit Breaker Vs Vacuum Contact Unit
- Applications
- Advantages and Disadvantages