Low voltage 4 pole mcb 63 amp switchgear assembly is a relatively closed environment, and there are many factors affecting its continuous running current. The interaction among the protection grade, the heat of the air breaker, the rated continuous current of the air breaker and the external ambient temperature is often ignored and no effective countermeasures have been taken. First of all, the higher the level of protection, the more tight the cabinet seal, the heat generated inside the more difficult to emit. Secondly, the ambient temperature outside the cabinet, the number of circuit breakers installed in the cabinet, the way of installation, the number of circuit breakers in and out of the line connecting the root of the copper bar, the specifications and the way and the partition structure in the cabinet will affect the heat and temperature appreciation in the cabinet. Therefore, when choosing the air circuit breaker installed in the complete set of switchgear, we must pay attention to the influence of various factors in the cabinet on the rated current of the circuit breaker, that is, when the air circuit breaker is installed in the closed complete set of switchgear, it is necessary to reduce the capacity to use, at the same time, but also to take the necessary ventilation measures. If these factors are ignored, neither considering capacity reduction, nor taking necessary ventilation and heat dissipation measures are still used according to the rated value for a long time, it will lead to overheating damage of the circuit breaker and cause serious failure, such accidents and cases can often be seen.
In the process of design and selection, the rated current value corresponding to the continuous current value for long-term operation must be selected according to different levels of environmental conditions, and be modified according to the ambient temperature.
In addition to high and low voltage classification, there is another classification of 4 Pole Mcb 63 Amp circuit breakers: different classifications of working positions in the power system
(1) Generator circuit breaker. It is mainly used to cut off the short-circuit fault of the generator bus. There are three main types of generator circuit breakers: less oil type, compressed air type and SF6 type. The oil-less type is used for circuits with small short-circuit currents, and the other two circuit breakers have strong breaking capacity.
(2) Power transmission circuit breaker. Circuit breakers working in 35kV and above transmission systems. This type of circuit breaker requires automatic reclosing, and due to the need for system stability, there should be a short breaking time and automatic reclosing no-current interval time (O ~ 2s).
(3) Distribution circuit breaker. Working in a power distribution system below 35kV, the rated voltage is 6-10kV, the rated current is 200-1250A, and the rated breaking current is small, starting from ensuring the reliability of power supply. This type of circuit breaker still has requirements for automatic reclosing, and because it has less impact on the stability of the system, the no-current interval time of automatic reclosing can be larger (0～5s), and the requirements for breaking time can also be appropriately relaxed .
The role of circuit breakers
1. Control. That is, according to the operation needs, put in or cut off part of the power equipment or lines.
2. Protective effect. That is, when the power equipment or line fails, the relay protection and automatic devices act on the circuit breaker to quickly remove the faulty part from the power grid to ensure the normal operation of the non-faulty part of the power grid.
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