Circuit Breaker of Diesel Generator Set

Circuit breaker is a switching device, under its action, diesel generator set can turn on, load and break the current which is under normal and abnormal circuit conditions within a specified time.

Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. But the demarcation line between high and low voltage is relatively vague. Generally speaking, the voltage more than 3kV is called high-voltage electrical appliances. Low voltage circuit breaker is also called automatic switch, commonly known as "air circuit switch". It is a kind of electric appliance that can not only switch manually, but also protect electricical equipment. 

Diesel generator automatic air circuit breaker is a low-voltage automatic switching device, which is usually used in circuits with AC voltage below 500V. In normal operation, it is used to turn on or break the main circuit; in abnormal operation, it is used to protect the main circuit from overload, short circuit and undervoltage, and automatically cut off the circuit. And after breaking the fault current, there is no need to change parts.

Distribution output of diesel generator set is through circuit breaker. Circuit breaker can protect the alternator of generating unit from being damaged by overload current or other abnormal impact. Circuit breaker has high breaking ability and automatic tripping ability. Users can directly draw power cable from the lower end of the circuit breaker to load when conducting power connection.

In a word, the function of a circuit breaker is control action and protective action.

Control function: input or remove part of power equipment or lines according to operation requirements.

Protective action: when the power equipment or line fails, the breaker is acted on by relay protection and automatic device, and the fault part is removed quickly from the power grid to ensure the normal operation of the non-fault part of the power grid.

There are some requirements for circuit breakers:

1.Circuit Breakers should be able to work reliably for a long time under rated conditions.

2.Sufficient short circuit capability should be included.

Since the grid voltage is relatively reliable and the current is large, when the circuit breaker is disconnected, a strong arc is generated between the contacts, and the circuit can be opened only when the arc is completely extinguished. Therefore, circuit breakers are required to have sufficient short-circuit capacity, especially in the case of short-circuit faults, they should be able to reliably cut off short-circuit current, and ensure sufficient thermal stability and dynamic stability.

3.The shortest possible start time should be included.

When a short-circuit fault occurs in the power grid, the circuit breaker is required to quickly cut off the fault circuit, which can shorten the fault time of the power grid and reduce the short-circuit current damage to short-term equipment.

4.Simple structure and low price.

When safety and reliability are required, economics should also be considered. Therefore, the circuit breaker should be simple in structure, small in size, light in weight, and low in price.

The types of circuit breaker:

China air circuit breakers have device type, universal type, fast type and current limit type, etc., commonly used device type is DZ10 series automatic air circuit breaker, universal type DW94, DW95, DW98 and other models, as well as DZ10 automatic air circuit breaker.

Besides, maybe circuit breaker has faults during working. There are two kinds of common faults in circuit breaker of diesel generators:

1.Circuit breaker automatic trip.

Solution: the diesel generator set overload or short circuit trips. If the circuit breaker occurs fault, we need to maintain or replace it.

2.The circuit breaker cannot be closed.

Solution: the breaker handle can only be closed after it has been disconnected. For parallel control, not synchronized, cannot be closed. It is the fault of circuit breaker, we need to maintain and replace it.