cầu chì cắt nhanh RS7N-200V/850A 900A 1000A 1100A 1200A 1250A

1. Main advantages and characteristics of fuses

1) Good selectivity. As long as the rated current of the fuse link of the upper and lower level fuses meets the requirements of the overcurrent selection ratio of 1.6:1 stipulated in the national standard and IEC standard, that is, the rated current of the upper level fuse link is not less than 1.6 times of the value of the lower level, it is regarded as the upper and lower level fuses. Selectively cut off fault current;

2) Good current limiting characteristics and high breaking capacity;

3) Relatively small size;

4) The price is cheaper.

2. Main disadvantages and weaknesses of fuses

1) The fuse link must be replaced after the faulty fuse blows;

2) The protection function is single, with only a period of overcurrent inverse time characteristics. This protection is used for overload, short circuit and ground fault;

3) When one phase fuse occurs, the adverse consequences of two-phase operation of a three-phase motor can be compensated for by a fuse with an alarm signal. One phase fuse can disconnect three phases;

4) Remote control cannot be realized and it needs to be combined with the electric knife switch and switch.

Non-selective circuit breaker:

1. Main advantages and features

1) After the fault is disconnected, it can be manually reset without replacing components, unless maintenance is required after cutting off the large short-circuit current;

2) The long-time delay release and the instantaneous current release with inverse time characteristics have two-stage protection functions, which are used for overload and short-circuit protection respectively, and each performs its own duties;

3) Remote control can be achieved when the electric operating mechanism is installed.

2. Main shortcomings and weaknesses

1) It is difficult to selectively cut off the non-selective circuit breakers of the upper and lower levels. When the fault current is large, it is easy to cause both the upper and lower level circuit breakers to be disconnected instantaneously;

2) The relative price is slightly higher;

3) Some circuit breakers have small breaking capacity. If a circuit breaker with a small rated current is installed close to a large-capacity transformer, the breaking capacity will be insufficient. Existing products with high breaking capacity can meet the requirements, but the price is higher.