Control Wiring Exercises
Hand Off Auto HOA controls are a very common and versatile control circuit which allows both automatic and manual operation.
It allows loads such as motors, solenoid valves, electric cylinders, etc. to be controlled by some automatic operation such as a sensor or PLC plus allows you to easily turn the load on manually or off manually.
HAND will run the load regardless of external factors including the normal control, over-travels, and other interlocks.
OFF will prevent the load from running regardless of what signals are coming from the automatic circuit. NOTE, this is not a substitute for a lockout tagout!
AUTO will run the load based off of an automatic control circuit.