A Complete Guide To Vacuum Circuit Breaker Testing Procedure

What are the Steps in Vacuum Circuit Breaker Testing? Vacuum Circuit…

What are the Steps in Vacuum Circuit Breaker Testing?

40.5KV ZW7 vcb

Vacuum Circuit Breakers are essential for the safe operation of any switchgear.

Testing of these circuit breakers is an important part of their maintenance regime.

The tests involve visual inspection, contact resistance test,vacuum interrupter integrity test, high potential test, MAC test and mechanism check. In this blog, we will specifically discuss the testing measures of vacuum circuit breakers.

In other words, this blog is a one-stop destination for everyone looking for both mv and hv vcb testing lately. Read the following items to know the vacuum circuit breaker testing procedure.

How Testing of Vacuum Circuit Breaker is Performed?

Testing of a Vacuum Circuit Breaker is an important activity before the circuit breaker is used in any power system. This test is used to check the operation of the circuit breaker and verify that it will trip at the right high current. The test is conducted using a test set, which includes test leads and other necessary equipment.

The circuit breaker test includes timing tests, open and close operation tests, coil tests, contact resistance tests as well as current carrying capacity tests. These tests are used to check all features and determine if the circuit breaker will work properly in its intended environment.

Additionally, these tests are also used to check for any potential problems that could arise during its use in a power system. Finally, after successful testing of a vacuum circuit breaker it can be safely used for its intended purpose in any power system.

vacuum circuit breaker used in KYN61 switchgear

1. Visual Inspection

The most basic and straightforward method of examination is to inspect it visually. Elements such as the drive insulators and molded pole unit support can be observed for any dirt or breaking. The control circuit components like wiring and terminals should also be checked to ensure they are intact.
 

A visual examination is used to test for dirt and debris in the machinery. In addition to looking, one can also use their sense of touch to evaluate certain components. Such as ascertaining the tightness of hardware or moving parts.

2. Contact resistance test

A micro-ohmmeter is used on the joined circuits of the VI and its resistance is logged. This value is then compared to the planned and/or normal values for other vacuum interrupts in that particular batch.

3. Vacuum Interrupter Integrity Test

VS1 type vcb used in KYN28 switchgear

The dependability of a vacuum circuit breaker is contingent upon the soundness of the vacuum and the built-in dielectric strength. To examine both, a vacuum interrupter test is conducted. This testing procedure for the vacuum circuit breaker is also referred to as a hipot test due to the high voltage utilized during examination.

This one-minute ac high potential test is utilized to assess the insulation quality from the primary circuit to ground, from the command circuit to ground, and between major circuit terminals.

A prosperous withstand indicates that the vacuum interrupters are properly operating whereas a breakdown implies that there is a faulty interrupter or interrupters which require being mended or substituted.

4. High Potential Testing

A high potential voltage is applied across the open contacts of the VI. The voltage is increased to the test value and any leakage current is measured.Factory testing may be done with either AC or DC high-potential test sets .

There are a variety of portable test sets available from manufacturers for performing a high-potential test on open vacuum interrupters. The great majority of these test sets are dc test sets, as they are considerably more compact, and hence, more portable, than available ac high-potential test sets.

5. The Leak-Rate Test (MAC test)

This experiment is based on the Penning Discharge Theory. It was determined by Penning that when a strong voltage is utilized to separate contacts in a gas and the contact design is encompassed with a magnetic field, the measure of current flowing between the plates depends on the gas pressure, the applied voltage, and the strength of the magnetic field.

6. Mechanism Check

An analysis of the mechanism entails a visual examination of the instrument for any loose components like rings, screws, and so on. Other aspects of the check could include a measurement inspection, performance check, operational assessment, or a mix of these. The measurement evaluation is needed to inspect vacuum interrupters for the presence of three contact corrosion indicators and contact wipe measurement.

In order to ensure the motor is working properly, a performance test needs to be conducted. Similarly, if there is any damage or distortion in the machinery, then visual and operational assessments are carried out. Occasionally, certain components need to be tested for accurate and smooth running. This may include turning off the circuit breaker, as well as manual loading.

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