Primary current injection test of circuit breaker

The primary current injection test is a type of test used to evaluate the performance of a circuit breaker. It is a widely used test method for circuit breakers, and it is described in various international standards, such as IEC 62271-103 and IEEE C37.09.

Principle:

The primary current injection test involves injecting a controlled current into the circuit breaker's primary circuit, which is the circuit that supplies the breaker's operating mechanism. The test is designed to simulate the maximum fault current that the breaker is expected to interrupt, and it is used to verify the breaker's ability to interrupt the fault current and to measure its performance.

Test setup:

The test setup typically consists of the following components:

  1. A current source: This is a device that generates a controlled current, which is injected into the circuit breaker's primary circuit.
  2. A current sensor: This is a device that measures the current flowing through the circuit breaker's primary circuit.
  3. A voltage source: This is a device that supplies the voltage required to operate the circuit breaker.
  4. The circuit breaker under test: This is the circuit breaker that is being tested.

Test procedure:

The test procedure typically involves the following steps:

  1. Connect the current source, current sensor, and voltage source to the circuit breaker's primary circuit.
  2. Set the current source to the desired test current, which is typically the maximum fault current that the breaker is expected to interrupt.
  3. Apply the test current to the circuit breaker's primary circuit.
  4. Measure the current flowing through the circuit breaker's primary circuit using the current sensor.
  5. Measure the voltage across the circuit breaker's primary circuit using a voltage sensor.
  6. Record the test results, including the current and voltage measurements.
  7. Repeat the test for multiple cycles to ensure that the breaker's performance is consistent.

Test objectives:

The primary current injection test is designed to verify the circuit breaker's ability to interrupt the maximum fault current and to measure its performance. The test objectives typically include:

  1. To verify that the circuit breaker can interrupt the maximum fault current.
  2. To measure the circuit breaker's interrupting capacity.
  3. To measure the circuit breaker's operating time.
  4. To measure the circuit breaker's recovery voltage.
  5. To verify that the circuit breaker's operating mechanism is functioning correctly.

Advantages:

The primary current injection test has several advantages, including:

  1. It is a widely used and accepted test method.
  2. It is a non-destructive test, which means that it does not damage the circuit breaker.
  3. It can be used to test circuit breakers of various types and sizes.
  4. It provides a comprehensive evaluation of the circuit breaker's performance.

Limitations:

The primary current injection test has several limitations, including:

  1. It is a laboratory test, which means that it may not accurately simulate real-world fault conditions.
  2. It requires specialized equipment and expertise.
  3. It may not be suitable for testing circuit breakers that are installed in the field.
  4. It may not be able to detect all types of faults or malfunctions.

In summary, the primary current injection test is a widely used and accepted test method for circuit breakers. It is designed to verify the breaker's ability to interrupt the maximum fault current and to measure its performance. While it has several advantages, it also has some limitations that should be considered when planning and conducting the test.