Air circuit breakers are a vital layer of protection against overcurrent’s and short circuits, breaking the circuit if there is a fault. They are there to ensure that your electrical systems stay stable and reliable. Therefore, it’s important that your air circuit breakers are always in good working order.

What are air circuit breakers?

Air Circuit Breakers (ACBs) are electrical devices that protect electric circuits over 800 Amps to 10K Amps. These are usually used in low voltage applications below 450V. They are widely used in industry for controlling and protecting different parts of a circuit such as motors, transformers and generators.

How do air circuit breakers work?

The basic function of an air circuit breaker is to interrupt current flow after a fault is detected, using air as an arc extinguishing medium. When a high current or voltage is interrupted, an arc is generated. The length of the arc is generally proportional to the voltage while the intensity (or heat) is proportional to the current. This arc must be contained, cooled and extinguished in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit.

Circuit breakers are usually able to terminate all current very quickly. Typically, the arc is extinguished between 30 ms and 150 ms after the mechanism has been tripped, depending upon the age and construction of the device. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset to resume normal operation.

What faults can occur with air circuit breakers?

Air Circuit Breakers are the cause of almost 20% of power distribution system failures.

This is mainly due to a lack of maintenance, dust, hardened grease, corrosion or frozen parts that prevent the proper operation of the trip linkage. Common faults we find with air circuit breakers can be them not turning on or off, not charging up or resetting or not tripping off as required. Other problems include the breaker not staying closed when turned on and erratic or nuisance tripping off of the breaker.

Why do I need to service and maintain my air circuit breakers?

For industries that operate at high voltage or power supply, it is important to protect machinery from overflows of current. Sudden high voltage surges can cause considerable damage to the overall performance of a plant. As with all electro-mechanical devices, electrical equipment manufacturers recommend regular maintenance of your air circuit breakers to ensure they can operate properly and to keep your equipment warranties valid. Regular servicing can prolong the life of your air circuit breakers, so they rarely need to be replaced.

Most importantly by servicing air circuit breakers regularly you can reduce any downtime and improve your equipment’s reliability because damaged or worn components can be identified before they fail. We have seen many instances where dirt on busbars and loose connections can cause noise, excessive heat and ultimately system failure due to lack of maintenance.

How can Equiptest help me?

calender with penEvery site and ACB is different, therefore after a discussion with you we will create a service schedule that suits you and your site. The schedule depends on the environment your ACBs operate in, and how often they are utilised. Too little use causes as much need for maintenance as excessive use.

An Equiptest service plan enables us to service your Air Circuit Breakers on site if they are fixed. If we can remove them, we may service them at our premises. During the service we disassemble certain elements of the ACB to allow inspection, lubrication, repair and testing. We have a range of specialised secondary injection equipment to enable us to test the operation of the ACBs electronic trip units and their parameters.

To find out more about the service we can provide Contact Us today.