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
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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