Two Ways in Which Industrial Circuit Breakers Are Used
There are at least two separate ways where industrial circuit breakers are used – in power distribution and in machine or process controls. Most machine tool controls have at least one breaker used as the main disconnect. These are usually molded case designs and may be fused for further protection. Inside a machine or process control panel there may be several secondary circuit breakers for various control circuits. These are usually mounted on DIN rails and may be one-, two- or three-pole configurations.
Applications for an Industrial circuit breaker
The second common application for industrial Circuit Breakers is industrial power distribution. This can range from the main circuit breaker in any facility to a circuit breaker found in any sub-panel throughout the facility. The main breaker can be one of four common types: molded case, insulated case, air frame or vacuum circuit breakers. Each of these types is suitable for specific applications. The most common in small to medium facilities is the molded case breaker. This type is most similar to the common residential main breaker but it is normally a three-pole configuration rated at 480 volts and up to 2500 amps. It shares a breaker panel with several smaller breakers of the same type.
Insulated case circuit breakers are a bit larger than the molded case type and are rated for higher voltages (up to 600V) and current ratings from 800 to 6000A. These are sometimes rated for 200kA interruption. They can be equipped with several accessories including digital trip units, phase monitoring and diagnostic displays.
Air Frame and Vacuum Circuit Breakers
Air frame and vacuum circuit breakers are often found in medium voltage applications (600 – 2500 Volts) in large manufacturing or mining operations. Air frame breakers normally use stored energy systems to open and close the contacts more quickly than direct manual operation. They also normally include some method of quenching arcs when opened under load. This is usually a magnetic arc chute but it can be some kind of pressurized air system.
Vacuum circuit breakers are found in medium to high voltage situations up to 38kV. They enclose the contacts in vacuum to minimize arcing at high current and voltages. The small gap between contacts also makes them faster to open when tripped. They can open in as few as three cycles.
The industrial circuit breakers are a vital component in the operation of any facility. Most of the time the devices quietly perform their duties with minimal problems. As with any man-made device there is the possibility of failure. When a circuit breaker fails it is important to have all the information about type, current rating, voltage rating, current interrupting rating and accessories before specifying a replacement. The same information is needed when ordering breakers for new installations. All manufacturers of industrial circuit breakers have websites where this information can be found and most offer online help and design services for difficult situations.
For large air frame, vacuum, and high pressure contact breakers there are maintenance and repair services available. A properly maintained breaker will deliver many years of uninterrupted power for any facility.
