Molded case circuit breakers and air circuit breakers both have their unique applications in the field of electrical protection, and there are several key differences between them. The following is a detailed comparison of the two types of circuit breakers:
1. Working principle
Molded case circuit breaker
Molded case circuit breaker is a leakage circuit breaker that works mainly by detecting whether there is an abnormality in the current. When the current exceeds the set value or there is leakage, it immediately interrupts the circuit to protect equipment and personnel from potential dangers.
Molded case circuit breakers usually contain electromagnetic release devices and thermal release devices inside. The electromagnetic release device is used to quickly cut off the current caused by a short circuit, while the thermal release device is used to cut off the circuit under overload conditions.
Air circuit breaker
Air circuit breaker is a magnetic circuit breaker whose working principle is based on the magnetic field force in the circuit. When the current in the circuit exceeds the rated value, the magnetic field force drives the mechanism inside the circuit breaker to act, thereby cutting off the circuit.
Air circuit breakers use compressed air or contacts to swing rapidly to blow out the arc to interrupt the current. In air circuit breakers operating under atmospheric pressure, an arc will appear between the contacts that disconnect the circuit, and the circuit breaker extinguishes this arc through a specific design.
2. Scope of application and carrying capacity
Molded case circuit breakers
Molded case circuit breakers are usually suitable for low-power circuits and occasions requiring high insulation performance due to their compact structure, light weight and relatively low price.
The shell is made of plastic or resin, so it does not have the ability to carry large currents.
Air circuit breakers
Air circuit breakers can carry higher currents and are usually suitable for high-power circuits and high-voltage power systems.
The shell is usually made of metal, which is heavier and larger in size, but has higher mechanical strength and thermal stability.
3. Appearance and price
Appearance
The shell of the molded case circuit breaker is made of plastic, has good insulation and moisture resistance, and is suitable for use in various environments. It is compact and light in weight, easy to install and maintain.
The shell of the air circuit breaker is usually made of metal, which is relatively bulky and large in size. But its structure is more rigorous and can withstand higher pressure and temperature.
Price
Generally speaking, the price of molded case circuit breakers is relatively low because they are cheap to manufacture and are suitable for a wider range of occasions.
The price of air circuit breakers is relatively high because they are expensive to manufacture and are suitable for more demanding occasions.
IV. Applications
Molded case circuit breakers
Commonly used in power distribution systems in residential, commercial buildings and small industrial facilities.
Also suitable for some electronic equipment that requires higher insulation performance and reliability.
Air circuit breakers
Commonly used in large industrial facilities, power plants and high-voltage power systems.
Also suitable for some occasions that need to withstand high currents and high voltages, such as motor control and power transmission and distribution systems.