The rotary switch is also a kind of knife switch in essence, but the operating handle of the common knife switch rotates upward and downward in the plane perpendicular to the installation face while the operating handle of the rotary switch rotates towards left and right in the plane parallel to its installation face. It can be used to switch on or switch off the circuit, change over the power supply or load, measure triphase voltage, control the forward and backward rotation of the small-sized motor. 

There are many series of change-over switches, here only the product of HZ10 series produced with national unified design is introduced. It has advantages such as long service life, reliable use, simple structure, etc., and it is suitable to be used in leading power supply of AC 50HZ, 380V, DC 220V and below, the direct starting of motor with small capacity of rotary switch structure below 5KW, and the control of upward or downward rotation of motor and illumination control circuit  for machine tool, but the number of switching time per hour is should not exceed 15-20 times.

The exterior and internal structures of HZ10-10/3 type of change-over switch consist of multi-section contact terminals, so it is also called as combination switch. 

HZ10 series of change-over switches are selected and used according to the variety of power supply, voltage grade, the required contact terminal number and motor capacity. The rated current of switch takes 1.5-2.5 times of motor rated current generally. 

When installing and using rotary switch , please pay attention to the below items:

In installation of rotary switch, it is suitable to keep hand shank in horizontal rotation position. 

The on-off capacity of rotary switch is low, so it cannot be used for breaking current with faults. When the upward and backward rotation of motor is controlled, it is not allowed to switch on in reverse direction only after motor stops rotation completely.

When the loaded power factor is very low, the capacity of rotary switch shall be reduced to use. Otherwise, it may affect the service life of switch; if the loaded power factor is less than 0.5, because of the difficulty in arc blowout, it is unsuitable to adopt HZ rotary switch. 

There are many wiring modes for rotary switch, so it is required to correctly select and use the product with corresponding specification according to the practical requirement. But the rotary switch itself doesn’t have overload or short circuit protection. If the circuit requires the above protection, then the protection device shall be equipped separately at the same time. 

The operating times should not be too frequently, usually it shall not exceed 300 times per hour usually, and otherwise, if the contact terminal is mechanically worn too fast, the metal powder will be easily left in the gap of the contact terminal to cause bad insulation.