Course Description

FUNDAMENTALS OF VARIABLE SPEED CONTROL

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Application

Cite industrial applications of variable speed motor control circuits.

Definitions

Define parameters, torque, acceleration, deceleration, p.w.m., frequency, voltage/hertz ratio, boost, I.R. compensation, and high bus fault as applicable to variable speed motor controllers.

AC FREQUENCY DRIVES

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Application

Describe how an AC frequency drive operates to vary motor speed.

Installation

Install an AC frequency drive to control motor speed.

Calibration

Set up and calibrate an AC frequency drive (change parameters).

Two speed motors

Determine the interconnections needed for various AC motor speed applications on two speed motors.

DC VARIABLE SPEED DRIVES

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Torque and speed

Describe the relationships of torque and speed to series, shunt, and compound DC motors.

Application

Diagram armature rheostat variable speed circuits for DC motors.

Diagram compound variable speed DC motors.

Describe methods used to obtain variable speed control of compound DC motors.

Installation

Install a DC variable speed drive for a DC motor.

Calibration

Calibrate a DC variable speed drive for a DC motor.

INSTALLATION PROCEDURES

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Control cabinet

Select appropriate control cabinets for variable speed motor control circuits.

Operator’s control station

Sketch floor plans for the installation of variable speed motor control systems.

Electrical accessories and conductors

Sketch the layout of electrical accessories and conductors used in variable speed motor control circuits.

Circuit wiring

Install components, wire control cabinets, operator’s stations, and motors for variable speed DC motor circuits.

Install components, wire control cabinets, operator’s stations, and motors for variable speed AC motor circuits.

RANGES

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Synchronous speed

Explain the formulas for determining the synchronous speed of AC motors.

Diagram a bank of starters used to achieve speed ranges for AC motors.

Interlock circuit or device

Sketch circuits which use mechanical interlocks for starters in AC motor variable speed controllers.

Sketch circuits which use auxiliary contacts for interlocks between starters in AC motor variable speed controllers.

Sketch circuits which use pushbuttons for interlocks between starters in AC motor variable speed controllers.

Limiting factors

Describe the limiting factors of speed ranges for variable speed DC motor controllers.

Evaluate the use of DC motors and variable speed controllers in specific industrial applications.