Anti internal arc design of low-voltage switchgear

Have you ever assessed the severity and probability of arc flash hazards? Will high arc flash incident energy damage your equipment and result in longer downtime? Or do you use protective and preventive control measures to identify and minimize damage and risk? Due to the lack of real-time feedback on the health status of the system, have you built unnecessary redundancy in the system? These are some questions you must answer when developing effective programs for your installation.

Low voltage switchgear requires unique functional design to greatly reduce the incidence energy (severity) and probability (probability) of arc flash. These features provide you with the necessary protection and preventive control measures, and make them an integral part of the switchgear design.

Like the anti internal arc design of medium voltage switchgear, low voltage switchgear also needs to improve the flash hazard of the following functions built into the kit design by reducing the risk of arc:

1. Door closing operation, combining door closing rocking in with remote rocking in, reduces the risk of operator injury when the potential risk is highest.

2. Insulated busbars and connection parts are equipped with insulation covers, greatly reducing the possibility of arc flash.

3. The functional units are completely isolated.

a. The circuit breaker is located inside the grounded metal compartment and is equipped with an automatic safety valve and a door closing rocker, which increases safety.

b. The control switches, fuses, and indicator lights are located on separate, easily accessible metal instrument panels above each circuit breaker.

4. There is no ventilation opening on the front door of the circuit breaker to ensure that if an arc flash does occur, the by-products of the arc will be restricted from leaving the switchgear from the front and causing harm to the operator.

The locking/listing process is crucial in any operational procedure. With the built-in functions of low-voltage switchgear, these operations are easy to perform.

a. The circuit breaker doors are interlocked to prevent them from being opened when the circuit breaker is in the connected position.

b. The pull-out guide rail on the lower structure can be padlocked to prevent the circuit breaker from being pushed in during maintenance of downstream circuits.

c. The safety valve can be locked in the closed position to prevent accidental contact with live parts when removing the circuit breaker from the switchgear.

d. Circuit breakers can be padlocked in the open position to prevent them from being opened.

The most important ones are the arc protection device and RELT, which are unique patented technologies that balance system reliability and safety.

Breakers and circuit breakers will reduce the incident energy of arc flash through state-of-the-art protection and fast operation time. Low energy RELT is allowed to pass, and the safety RELT device for protecting operation and maintenance personnel allows users to reduce the level and time span of short-circuit current, thereby reducing energy near the circuit breaker.

The main benefits of reducing maintenance system with flashing arc:

Increased personnel safety - by limiting the flash energy at the fault point

Easy to operate

Only enabled during maintenance work execution

Maintain coordinated protection of circuit breakers under normal conditions

Reducing the level of incident energy can allow for a reduction in personal protective equipment (PPE), thereby improving worker comfort and mobility

Reducing energy through RELT will further reduce arc flash incident energy by up to 20%, and is typically enabled when maintenance of energized downstream equipment must be carried out at close range.