33 Three-Wire Circuit With Pilot Lights

Three-wire control circuit with pilot lights

Motors are often installed in loud environments or at remote locations, and so simply relying on the sound of a running motor to tell an operator its status is unreliable. To aid with this, we can connect pilot lights in our control circuit to indicate the running status of a motor. Pilot lights that are installed in the control circuit in parallel with the motor starter will be energized when the motor is energized. These are often referred to as motor running lights.

Pilot lights must NEVER be installed in series with motor starters; the motor starter might not have enough voltage to pull in, and if the filament in the pilot light burns out, it will create an open in series with the rest of the circuit.

Motor starters often come with auxiliary contacts beyond the normally open 2-3 holding contacts, and if not, many starters can have additional auxiliary contacts added to them.

If a motor starter has a set of normally closed contacts these can be wired in series with a pilot light. As long as the motor starter is not energized, the contacts will remain closed and the light will be on. This can indicate to an operator that a motor is in the off or de-energized condition.



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Basic Motor Control Copyright © 2020 by Aaron Lee and Chad Flinn is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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