The fuse circuit in the power supply circuit plays an overcurrent protection role. When the current flowing through the circuit reaches a certain level, the fuse in the circuit will automatically fuse, cut off the current circuit, and prevent the large current from further damaging other components in the circuit. So fuse is applied in many circuits that need circuit protection. Different circuits have different requirements for fuses. This article will introduce the application of fuses.
The power circuit fuse is mainly used to protect low-voltage electrical equipment in the production process and daily life of industrial and mining enterprises. Because it is used in different electrical equipment, the selection principles of its capacity and size vary greatly. In practice, it must be selected and configured in strict accordance with the regulations. Otherwise, it will lose its due protection. Generally, most of the control and signal circuit fuses of electrical equipment shall be no more than 6A.
For the electromagnetic closing circuit of the electromagnetic closing mechanism of the circuit breaker, the rated current of the fuse shall be 0.25-0.3 times of the rated closing current: Ie=Kph * IHQ.max, and Kph shall be 0.25-0.3; For DC motor without starting resistance, select according to avoiding starting current: Ie=Iqd/Kph, Kph is 3; DC motor with starting resistance shall be selected according to 1.05 times of motor rated current. Considering the importance of DC oil pump in power plant and steam turbine generator unit, the actual selected capacity is slightly larger than the design value to ensure the safety of main engine.