Structure and model meaning of rotary switch

Rotary switches are also essentially knife switches. However, the operating handle of the ordinary knife switch rotates up or down on the plane perpendicular to the mounting surface,Rotary switchThe operating handle is rotated to the left and right on a plane parallel to the mounting surface. It can be used to connect or disconnect circuits, replace power supplies or loads, measure three-phase voltages, and control the forward reversal of small motors.

　　Rotary switchThere are many series, here only introduce the national unified design products HZ10 series. It has the advantages of long life, high reliability and simple structure, and is suitable for power input below AC 50Hz, 380V and DC 220V.

In the direct start of small-capacity motors below the 5 kW, the forward and reverse control of the motor, and the lighting control circuit of the machine, the number of conversions per hour shall not exceed 15 to 20 times.

HZ10-10/3 type switch shape, the internal structure is shown on the right. It is composed of multiple contacts, so it is also called a combination switch.

The HZ10 series transfer switch is selected according to the type of power supply, voltage level, the number of contacts required and the motor capacity. The rated current of the switch is generally 1.5 to 2.5 times the rated current of the motor.

installation and useRotary switchPlease note the following:

1. When installing the rotary switch, it is best to keep the handle in the horizontal rotation position. The rotary switch has a low cut-off capability and cannot be used to cut off the fault current. When the motor uses forward reverse control, the motor no longer completely stops rotating, which allows reverse connection.

2. When the load power factor is low, the capacity of the rotary switch should be reduced. Otherwise, the switch life will be affected. If the power factor of the load is less than 0.5, the HZ rotary switch should not be used because it is difficult to close the arc.

3. There are many wiring methods for rotary switches, so products of appropriate specifications should be selected more practically. There is no overload and short circuit protection function. If the circuit requires this protection, it must be installed separately.

Work should not be too ordinary, generally no more than 300 times per hour. Otherwise, the contact machine will wear too fast, and the metal powder will remain in the contact gap, which will easily cause poor insulation.

According to the electrical principle, if you want to fit the two stages of the power line connected to the motor, you can achieve forward reversal control.

The circuit works as follows:

When the rotary switch SA is pulled to the middle position, the three-phase winding power is cut off and the motor stops rotating.

When the rotary switch SA is pulled to the lower position, the power supply turns on the three-phase windings A, B and C of the motor M according to C, B and A, and the motor reverses.

The switch has no arc suppression device, so it can only be used when the motor capacity below the 5.5 kW is not frequently started, stopped and forward control. It is especially suitable for motor control in places such as elevators and electric cranes.