Print this page Protection of Low Voltage Circuits
Joseph E. Fleckenstein, P.E.
Course Outline
The course reviews the types of common overcurrent protective devices (OCPD’s), specifically circuit breakers and fuses. There are several types of circuit breakers, namely the molded case circuit breakers (MCCB), the insulated case circuit breakers (ICCB), the low voltage power circuit breakers (LVPCB) and the electronic circuit breakers. Each of these classifications of circuit breakers has unique properties that is suitable for a specific type of service. Fuses are the second, general type of OCPD that is treated. The most common types of fuses are the standard delay and the time-delay.
The process for selecting OCPD’s is reviewed in detail. It is important that an OCPD should be capable of avoiding long-time deterioration of insulation whenever potentially harmful currents might occur. The devices should also be capable of interrupting shorts.
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 a student will:
- Understand the general objectives of circuit protection;
- Understand the importance of grounding to circuit protection;
- Be familiar with the common types of circuit breakers;
- Be familiar with the different types of fuses;
- Be familiar with the recognized types of faults;
- Understand time-temperature-curves for OCPD’s;
- Know how to select OCPD’s to avoid deterioration of insulation;
- Know how to select OCPD’s for short circuit requirements;
- Know how to select OCPD’s to ensure coordination;
- Be familiar with a shortcut method of determining maximum short circuit current;
- Know how to account for asymmetrical currents in sizing OCPD’s; and
- Understand damage curves and their usefulness.
Intended Audience
This course is intended primarily for electrical engineers who may find need to select overcurrent protective devices for electrical circuits.
Benefit for Attendee
Attendees will learn the functions of circuit protective devices as well as the procedures for applying specific devices.
Course Introduction
A properly designed low voltage circuit must necessarily include means intended to prevent either injury or damage to property. The common practice to accomplish this end involves the use of overcurrent protective devices. Protective devices are available in a variety of types and sizes. A proper selection can be made only if an engineer is familiar with the various types as well as the respective capabilities and limitations.
Course Content
The course content is contained in the following PDF file:
Protection of Low Voltage Circuits
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Course Summary
This course teaches a familiarity with overcurrent protective devices for low voltage circuits and the proper application of these devices.
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
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.
