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Variable Speed Drives in Electrical Energy Management

A. Bhatia, B.E.

Course Outline

In today's environment with the increasing costs of energy, many electrical users are looking for ways to drive not only an appreciable cost savings but also would keep up system efficiency. One efficient and practical way to do this is the installation of variable speed drives that offer a means of controlling a motor.

Written in straightforward "user" language, this 4-hour online course provides a basic understanding of variable speed drives for the engineer or technician involved in specifying, applying, maintaining and operating variable speed drives.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will be aware of:

Intended Audience

This course discusses the energy efficiency improvement in induction motors and is aimed at Students, Electrical & Control Engineers, Mechanical & Process System Design Engineers, Energy Auditors, O & M Personnel and Sales & Marketing personnel.

Course Introduction

Variable speed drives allow you to match the speed of the motor-driven equipment to the process requirement. Until recently the majority of high performance industrial applications have been satisfied using DC motors and controls. The rapid development of adjustable frequency AC technology has changed the scenario.

Variable speed drives are devices used for varying the speed of driven equipment (such as pumps, blowers, compressors, conveyors etc.) to exactly match the process requirements and achieve energy saving as well. For an electrical engineer, it is just not sufficient to be satisfied with selecting the right type and size of motor. The knowledge of driven equipment and the application in the process areas, in fact, offer equal opportunities for the energy conservation.

Pumps, fans and compressors are the most commonly found equipment in varied types of industries and commercial use. On an average the power consumed by pumps alone varies between 5-30 % depending on the type of industry & applications. There is tremendous energy saving opportunity for achieving substantial energy savings through variable speed drives in these applications.

The course reviews the above criteria in detail and is followed by course summary and multiple - choice quiz at the end.

Course Content

The course content is in a PDF file Variable Speed Drives in Electrical Energy Management. You need to open or download this document to study this course.

Course Summary

By optimizing the efficiency of your motor-driven systems, you can increase productivity while saving significant amounts of energy and money. It is important to note that majority of savings shall accrue not on the motor itself but on the motor-driven system as a whole.

Though there are numerous methods ranging from mechanical drives, magnetic & hydraulic options, DC drives and others, there is none that compares to variable frequency drives when it comes to accurate process control.

With the advancements in power electronics, the modern AC variable speed drives are very close to the DC drive in terms of fast torque response and speed accuracy. However, AC motors are much more affordable than DC motors, making them far more prevalent.

Variable speed drives for AC motors are based on the principle of varying the frequency and can be programmed to run the motor at a precise speed, to stop at a precise position, or to apply a specific amount of torque.

The nature of the load dictates what type of motor is needed and how it needs to be controlled. The variable torque loads constituting fans and pumps are benefited the most with variable speed drive. The energy conservation benefits usually far exceed the payback periods.


Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.