DIN Rail Mounted Circuit Breakers Product Information

What is a Miniature Circuit Breaker? Miniature circuit breakers are used to automatically detect an "over-current" situation and disconnect the power source in order to prevent damage to the circuit. Miniature Circuit Breakers are used to interrupt the current flowing through a wire in a manner similar to the function of a fuse; however miniature circuit breakers do not need to be replaced each time. Instead of "blowing" or melting as a fuse does, the miniature circuit breaker "trips" as a result of excess current. Most miniature circuit breakers use a combination of heat and magnetism to determine when they trip. These are called "thermal-magnetic" breakers.

Miniature Circuit Breaker Specifications

Circuit breakers are usually characterized by the following parameters:

• The voltage rating
• The number of poles
• The maximum current or "trip rating"
• The interrupting capacity

The voltage rating and the number of poles are usually considered together. For example, if a single, 120 VAC circuit is being protected, then a single pole breaker with a minimum voltage rating of 120 VAC will be used. However, if the circuit feeds a 3-wire, 120/240 VAC device, then a 2-pole, circuit breaker will be required with a minimum voltage rating of 240 VAC.

The "trip rating" of the circuit breaker is not a precise value. Rather, the designer should consult the current trip curves for the breakers to determine how long an allowable overcurrent condition may be safely present. Typically, the more the "trip rating" current is exceeded the faster the breaker will interrupt the current.

Another consideration is the interrupting capacity. Very large, unexpected currents can cause the internal components of the circuit breaker to fuse thereby rendering it nonfunctional. Each circuit breaker is rated for the maximal amount of current that can be interrupted by the breaker. The designer should consider the power source to the circuit when selecting a breaker and insure that the "maximum interrupting capacity" of the breaker is not exceeded.

Types of Miniature Circuit Breakers

SCS supplies miniature circuit breakers for low voltage applications (i.e., less than 600 volts) that are used for control equipment. Most of these circuit breakers are designed to be mounted onto DIN standard rail. Special materials or construction techniques are required to reduce the arcing inside the breaker when the voltages increase. These medium and high voltage breakers may employ a vacuum or an oil-filled reservoir.

Weidmuller DIN Rail Mounted Miniature Circuit Breakers

Weidmuller offers a broad assortment of DIN rail mounted miniature circuit breakers to meet all of your control system overcurrent requirements. The 9926 Series is UL 489 Listed and offers a 10,000 Amp interrupting capacity. The CB4200 is a pushbutton-style of circuit breaker that provides rapid identification of tripped breakers. The CB2200 Series offers a narrow profile miniature circuit breaker that features integrated alarm contacts – an ideal feature for today’s control systems.

NEW! – Now Weidmuller offers the ESX10-T Series miniature circuit breakers. This line is Class 1 Div 2 approved making it an ideal choice for use in hazardous locations installations requiring this rating. These breakers include a remote reset feature that greatly reduces maintenance costs.

GE IEC DIN Rail Mounted Circuit Breakers

SCS stocks a full line of GE IEC DIN rail mounted miniature circuit breakers. This low-cost and reliable miniature circuit breaker is the perfect choice for your overcurrent protection needs.