Generally speaking, the use of circuit breakers is based on specific conditions of use, such as the rated current of the circuit and protection requirements, to determine specific parameters. For example, when the rated current is below 630A and the short-circuit current is not large, a molded case circuit breaker is generally used. Rated current is relatively large, you can use ACB, or use good performance molded case circuit breaker instead.
Molded case circuit breakers are also called device circuit breakers. All components are sealed in a plastic case. The auxiliary contacts, undervoltage releases, and shunt releases are modularized. Due to the very compact structure, the molded case circuit breaker cannot be overhauled basically, and the operation is mostly manual, and the large capacity can be opened and closed electrically. Molded case circuit breakers are generally used as branch protection switches.
The typical molded case circuit breaker is RMM1. The rmm1 series molded case circuit breaker is suitable for power distribution in a 50Hz distribution network with a rated working voltage of 400V and a rated current of 630A and below. Circuit breakers of 400A and below can also be used for motor protection. The rated isolation voltage of the circuit breaker is 690 volts. Distribution circuit breakers are used to distribute electrical energy and protect the lines and power equipment in the distribution network from overload, undervoltage and short circuit. The circuit breaker is used to protect the motor and prevent the motor from overload, undervoltage and short circuit.
Under normal conditions, the circuit breaker can be used for infrequent switching of lines and infrequent starting of motors. The circuit breaker can be installed vertically (vertical) or horizontally (horizontally). Molded case circuit breakers have compact structure and large switching capacity, and can be installed with various types and accessories.
First of all, we know that its shell is plastic. In other words, it uses a plastic insulator as the outer shell, which can effectively isolate the metal parts between the corresponding conductors. In addition, this type of circuit breaker usually has a thermomagnetic trip module, while for large circuit breakers, there will be a solid-state trip sensor. When a short circuit occurs, the insulation around the corresponding static contact will vaporize, which can be cooled and arc extinguished. The arc extinguishing chamber of this type of molded case circuit breaker adopts a metal grid structure. Compared with the contact system, it also has a repulsive force current limiting device. This design scheme greatly improves the breaking and current limiting capabilities of the circuit breaker.