How to Control Motors

The following video discusses how to control the motors you will be working with in this course and in your field.

Source: Cars Garage. “GM Manufacturing Plant.” YouTube video, February 22, 2014. GM Flint Manufacturing Plant.

Structure of a Motor Control Circuit

Control Devices are items connected between L1 and the load. They comprise the Decision Section of a motor control circuit. Control devices include things like buttons, switches, temperature sensors, pressure sensors, and proximity sensors.

The Action Section of a motor control circuit contains the load. A load is a device that converts electrical energy to motion, heat, light, or sound.

Normally Closed and Normally Open

Control devices can be "normally open" or "normally closed". A device that is normally open blocks current from passing through it until it is triggered as designed. A trigger can be different things, including a button press, reaching a temperature, or proximity. When the trigger occurs, a normally open device closes and allows current to pass.

A normally closed device works the opposite: it allows current to pass through it until triggered; a normally closed device blocks current when triggered.

A ladder diagram depicts control devices in their normal, untriggered state.

Logical Building Blocks of Decision Section

- AND - The load is energized when A and B are triggered.

- OR - The load is energized when A or B is triggered.

- NOT - The load is de-energized when A is triggered.

- NOR - The load is de-energized when A or B is triggered.

- NAND - The load is de-energized when A AND B are triggered.

It is attributed to: Rockis, Gary J. and Mazur, Glen A. (2009). Chapter 5. Electrical Motor Controls for Integrated Systems, 4th Edition.

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