On which of the following routine tests are conducted ?

The correct answer is: D. All of the above

Routine tests are conducted on all types of circuit breakers to ensure that they are functioning properly and can safely interrupt fault currents. These tests typically include:

• Visual inspection: This involves checking the circuit breaker for any signs of damage, such as cracks, leaks, or loose connections.
• Mechanical operation: This involves operating the circuit breaker to ensure that it moves smoothly and that the contacts close and open properly.
• Electrical operation: This involves applying a voltage to the circuit breaker to ensure that it can interrupt the rated fault current.
• Insulation resistance: This involves measuring the resistance between the live and neutral terminals of the circuit breaker to ensure that there is no leakage current.
• Dielectric strength: This involves applying a high voltage to the circuit breaker to ensure that the insulation can withstand the voltage without breaking down.

These tests are typically performed on a regular basis, such as every six months or annually. The frequency of the tests may be increased if the circuit breaker is used in a harsh environment or if it is subjected to a lot of wear and tear.

It is important to conduct routine tests on circuit breakers to ensure that they are safe and reliable. If a circuit breaker fails to operate properly, it could cause a power outage or even a fire.