The main control functions are done by the universal AC relay. The relay is usually driven by a push button or limit switch. Relay contacts can control the solenoid valve,

Larger starter motor and indicator lights. The voltage is generally 24VDC, 220VAC. Industrial machinery installation of environmental conditions must be considered,

Running industrial machinery and nearby equipment always carry some shock and vibration into the control cabinet; there is also the possibility of splashing cutting coolant.

Equipment manufacturers usually take some protective measures on the control components, but these adverse environmental conditions should still be considered when selecting and designing relays.