Tag: circuit breaker

Miniature circuit breaker, short for MCB, is one of the most widely used terminal protection appliances in building electrical terminal distribution devices. And this article shows the right selection of MCB based on its electrical parameters. The rated breaking capacity of MCB is the maximum short-circuit current value that can be broken without any damage to the circuit breaker. The miniature circuit breakers currently on the market generally have several rated breaking capacities, including 4.5kA, 6kA and 10kA according to the relevant technical data and design manuals provided by various manufacturers.

The advantages of indoor high voltage vacuum circuit breaker are not only oil-free equipment, but also long electrical life. It has mechanical life, large breaking insulation capacity, strong continuous breaking capacity, small volume, light weight, frequent operation, fire free, less operation and maintenance, etc. And they are quickly recognized by the operation, maintenance and technical personnel of the power department. The quality of some high voltage vacuum circuit breakers is not stable enough, the current carrying voltage is on the high side during operation and some vacuum interrupters still have air leakage. With the wide application of vacuum circuit breaker, faults also occur from time to time. The author analyzes the common faults of vacuum circuit breaker and gives treatment methods.

Safety switch is a switch that prevents people from entering a dangerous area before all safety conditions are met. Also it is a device that monitors current in various applications. Safety switches can be used in major equipment applications (conveyor belts, production line equipment, heavy equipment) and electrical protection of whole system. The safety switch works by monitoring the current and detecting electrical faults, which means that in case of leakage, short circuit, overload, the safety switch will cut off the power supply of the faulty system almost immediately (within a few milliseconds).

ATO miniature circuit breaker is mainly used for AC 50Hz or 60Hz, voltage ratings 230/400V, 240/415V and 277/480V, and current ratings from 1A to 63A. The miniature circuit breaker is characterized with compact structure, reliable performance, strong breaking capacity and beautiful appearance. It can be applied for overloading and short-circuit protection of lighting, distribution lines and equipment of office buildings, houses and similar buildings. The mini circuit breaker is also used for not frequently on-off operations and conversions on the lines.

1P, 2P, 1P+N, 3P, 4P, 4P+N, P means that the miniature circuit breaker (MCB) is equipped with a protective pole (knife pole), N means that the neutral conductor is only equipped with knife pole, but no protection modules. Both 2P and 1P+N are called two pole switch, 4P and 3P+N are called 4 pole switch. Neutral conductor of 1P+N and 3P+N don't have protection, so they are much cheaper, the neutral conductor pole acts along with the phase line pole. Some circuit breakers divide 1P+N into two types: one adopts two module width, another adopts one module width (small size). For these poles, how to select a right miniature circuit breaker?

Whether low-voltage circuit breakers are installed properly, which will directly affect its performance and safety. Generally pay attention as follows:

1. Before installation, the technical parameters listed on the nameplate of the low-voltage circuit breaker should be checked for compliance with the requirements.
2. Low voltage circuit breakers should be installed vertically, and the wired in front of the board are allowed to be mounted on metal brackets or metal backplanes, but the low-voltage circuit breakers that are wired behind the board must be mounted on the insulating base plate. The bracket or bottom plate of the fixed low-voltage circuit breaker must be flat to prevent damage to the insulating base when the screws are tightened. In order to prevent accidents caused by arcing, the copper busbar of the low-voltage circuit breaker should be packed with 200mm insulation or phase-interval arc plate from the insulation base.

Circuit breakers and fuses can protect the electric equipment and lines from short circuit. Actually, both have their own characteristics. Circuit breakers are used to switch on and off the load circuit as well as cut off the fault circuit, so as to ensure the safety. The fuse is used as a protector by melting itself when the current is too high or exceeds the load current. It is completely different from the circuit breaker on the breaking current. Its function can be easily understood by the commonly used fuse in our home.