Circuit breaker and fuse support, national electrical switch factory, www.guofadq.com
Most of the time, we in the purchase of circuit breakers, will consider whether the need for supporting fuse. Some feel that to be, some people don't think. In addition, in low voltage power network, we also need to consider the use of which switches and fuses with the use of simple, here we will discuss this problem.
In the earlier section, circuit breaker and fuse ability need. Now the competence mostly can meet, mainly on account of current limiting, such as electronic load and power supply switch can be used to fuse and breaker scheme. But at the same time, from a security point of view, the circuit breaker is in front of it is necessary to fuse. We all know the maintenance line must have a clear visual disconnect point is used to ensure the safety of maintenance personnel, and the circuit breaker is not as obvious cut-off point to use. So the circuit breaker are installed in front of the fuse or switch in repair of isolated power supply. At the same time it also can be thought of as a voltage level problems, general electric power sector of either 10kV or higher level of substation or power plant are not possible in a main circuit set high-voltage fuses, are generally in the protection and measurement circuit of voltage mutual inductor or transformer secondary circuit set the fuse device. So whether the customer of high voltage and low users, if set adds unnecessary trouble (that is, a number of failure points ) if a bad contact, or a phase fusing all users will bring loss ( phase motor burn ), provide a circuit breaker supplier of equipment can fully meet the in short circuit, low voltage, overload and abnormal state protection -- trip! If the user is not considered is low in the low voltage side of the transformer to install what the main fuse, because of the high voltage side of the transformer has installed a drop insurance ( actually is a fuse ).
Next we through diagrams to complement the text make a detailed analysis and description:
Actually we know: analysis of time current curve ( fuse ) is limit in 1.3 ~ 1.6 times of the rated current of the circuit breaker, and the long-time delay overload release left limit tripping current at 1.05 to 1.2 times the current setting. Circuit breaker with adjustable parameter L of overload tripping device, the current can be adjusted, thus limiting current can be associated with the object to be protected continuously load capacity fuse good mix. With the circuit breaker instead, fuses rated current grade can only roughly match, fuse overload current limit for cable and wire load design.
In the overload range, melting time current characteristic curve change more often than the overload tripping device to steep, this is in line with the wire and cable is a kind of load trip requirements, but not suitable for motor overload protection, motor overload protection requires malleable tripping characteristic curve. In short circuit current range, circuit breaker I parameters quick disconnect release action than the fuse quickly. The fuse can rapidly breaking large current, it can limit the impact of short-circuit current. Therefore: fuse in 660V AC voltage is above 100kA high breaking capacity, but the circuit breaker interrupting capacity and structure and the tripper rated circuit multiple related.
The following are the other aspects of performance comparison:
Properties of fuse circuit breaker
Remote breaking can not
All pole simultaneously breaking can not
Simulation of breaking can not
Atresia can't
In the overload after cut off again on ability can't
In short the ability after cut off again can't
The selective inability to
Arc spraying distance and the breaking capacity of small by the structure and the rated current rate decision
Current limit for In, Ik current limiting by the structure of the decision
Additional interrupter without
There is no limit to the number of maintenance cost
If the circuit breaker mounting may appear above the circuit breaker expected rated breaking capacity of short circuit current, should lead the fuse, the fuse in circuit breaker breaking short-circuit current breaking tasks prior to the implementation of. In circuit breaker and fuse combination, each of the devices are divided into their respective scope of protection: circuit breaker L parameter overload release monitoring overload current, instantaneous release for I capture with the circuit breaker breaking capacity of short circuit current. Only when the circuit has high short circuit current, the fuse will take off high short-circuit current liability, at the same time the circuit breaker can also ensure that the I release separate auxiliary breaking.
Country electric switch factory sales Low-voltage electrical switches, welcome calls