1) good selectivity. Supervisor fuse rated current of fuse body as long as meet the requirements of gb and IEC standards over current option than 1.6:1, i.e. the higher rated current fuse body is not less than the lower the value of 1.6 times, as a supervisor can selectively cut off the fault current;
2) good limit flow characteristics and high breaking capacity;
3) relatively small size;
4) the price is cheaper.
2. Main shortcomings and weaknesses of the fuse.
1) the fuse must be replaced after the fault is fused;
2) the protection function is single, with only one period of current inverse time, overload, short circuit and ground fault.
3) in the event of a phase fuse, the three phase motor will cause the adverse consequences of the operation of the two phases. Of course, the fuse of the alarm signal can be used to compensate, and the three-phase fuse can be disconnected.
4) the remote control cannot be realized, and it is possible to combine with the electric knife switch and switch combination.
Non-selective circuit breaker:
1. Main advantages and characteristics.
1) after the fault is broken, the manual operation can be reset without replacing the component, unless it needs to be repaired after cutting off the large short circuit current;
2) the two sections of protection function of the long time delay trip and instantaneous current tripping device with anti-time-limit characteristics are respectively used as overload and short-circuit protection, respectively.
3) the remote control can be realized when the live operating mechanism.
Major weaknesses and weaknesses.
1) it is difficult to realize selective cut-off between the upper and lower class non-selective circuit breakers. When the fault current is large, it can easily lead to the instantaneous disconnection of the upper and lower circuit breakers.
2) relatively high price;
3) partial breaker capacity is smaller, for example, if the circuit breaker with a small rated current is installed in the position of a large capacity transformer, the breaking capacity is not enough. The products with high breaking capacity can be satisfied, but the price is higher.
Selective circuit breaker:
1. Main advantages and characteristics.
1) the above advantages of non-selective circuit breakers;
2) with multiple protection function, with long time delay, instantaneous, short time delay, and ground fault (including zero sequence current and residual current protection) protection, overload respectively, cut-off time delay and large short-circuit current instantaneous movement and ground fault protection, protection of high sensitivity, adjust various parameters is convenient, easy to satisfy the distribution line protection requirements. In addition, there is a cascade protection function with better selective performance.
3) nowadays, the products have many intelligent features, besides the protection function, there are also power measurement, fault record, and communication excuses, so as to realize the centralized monitoring and management of power distribution devices and systems.
2. Main problems
1) the price is very high, so it should be used only in the first and especially important locations of distribution lines;
2) larger size.
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