Classic Case | 10kV Circuit Breaker Test Report

Original | Electrical Test Lecture Hall | July 08, 2026 11:30 | Zhejiang

PART 1: Main Information of On-site Test

• Test Time: 2023/6/19

• On-site Tester: Huo Qi

• Weather: Sunny

• Test Location: A certain substation

• On-site Situation: 10kV Circuit Breaker

• Instrument Used: Xianheng International HVS-12

Pictures of On-site Test Instruments

PART 2: Test Items

11.0.1 The test items for vacuum circuit breakers should include the following:

1. Measure insulation resistance;

2. Measure the resistance of each conductive circuit;

3. AC withstand voltage test;

4. Measure the opening and closing time of the circuit breaker, measure the synchronism of opening and closing, and measure the bounce time of the contacts during closing;

5. Measure the insulation resistance and DC resistance of the opening/closing coils and the closing contactor coil;

6. Test of the circuit breaker operating mechanism.

PART 3: Test Purpose

1. Ensure technical parameters meet regulatory requirements

• Performance Verification: Through mechanical characteristic testing, it can be verified whether the technical parameters of the circuit breaker meet the specified standards and specifications, such as opening and closing time, speed, etc., ensuring that the circuit breaker can be reliably put into operation.

• Action Accuracy: The test can evaluate the accuracy and stability of the circuit breaker's action, which is crucial for the protection and control of the power system.

2. Master the health status of the circuit breaker

• Detect Comprehensive Health Level: Mechanical characteristic tests can detect the comprehensive health level of the circuit breaker, including mechanical parameters and the coil operating voltage of low-voltage characteristics.

• Prevent Potential Problems: Through testing, potential problems of the circuit breaker, such as contact wear, improper stroke adjustment, etc., can be found in time, providing a scientific basis for equipment maintenance.

3. Guarantee the stability and safety of the power system

• Breaking Capacity: The mechanical performance of a circuit breaker directly affects its ability to break and close circuits, thereby affecting the stability and safety of the power system.

• Avoid Accidents: Appropriate opening and closing speeds can give full play to the breaking current capacity of the circuit breaker, reduce electrical contact wear caused by pre-breakdown during closing, and avoid contact burn-out, oil spraying, or even explosion.

4. Improve operation reliability

• Reduce Mechanical Failures: Through testing, the mechanical operation reliability of the circuit breaker can be ensured, reducing operation failures caused by mechanical faults.

• Optimize Maintenance Plans: Test results can help formulate more accurate and efficient maintenance and repair plans, extending the service life of the equipment.

5. Monitor action time and speed characteristics

• Action Time Monitoring: Including closing time, opening time, etc., which is crucial for the rapid response of the power system.

• Speed Characteristic Analysis: The movement speed of the contacts during the closing and opening process is an important part of mechanical characteristic monitoring and has a significant impact on breaking capacity.
  
  

PART 4: Test Process

Connect the instrument to the circuit breaker's control loop and fracture according to the method shown below. Set up according to the circuit breaker parameters and then test.Note: The tested circuit breaker is equipped with a locking switch, which needs to be turned on when closing.

PART 5: Operating Procedures

11.0.5 Measuring the opening and closing time of the main contacts of the circuit breaker, measuring the synchronism of opening and closing, and measuring the bounce time after the contacts touch during the closing process shall comply with the following regulations:

1. The bounce time after contact touching during the closing process: for circuit breakers below 40.5kV, it shall not be greater than 2ms; for circuit breakers 40.5kV and above, it shall not be greater than 3ms; for 10kV vacuum circuit breakers with a current of 3kA and above, if the bounce time does not meet the requirement of less than 2ms, it shall comply with the provisions of the product technical conditions;

2. The measurement should be carried out under the rated operating voltage condition of the circuit breaker;

3. The measured values should comply with the provisions of the product technical conditions.

PART 6: Test Summary

The mechanical characteristics of a circuit breaker are its physical characteristics. The mechanical characteristic tests we perform on circuit breakers include opening and closing time, speed, stroke, clearance, synchronism, bounce, etc. The mechanical characteristic of vacuum switches that has the greatest impact on electrical performance is the opening movement characteristic (i.e., opening speed), because if there is a problem with the mechanical characteristic of the circuit breaker, it will cause an impact and potential hidden dangers to the electrical performance.

By comparing the test results with the circuit breaker parameters, it can be concluded that all results of the circuit breaker are qualified.