In-person instruction

Fundamentals of Basic Relay Testing

Learning objective

At the completion of this course, students will be able to test phase / ground time over current (51) and phase / ground instantaneous over current (50) protection elements on electromechanical and microprocessor feeder protection relays.

Course abstract

Time overcurrent and instantaneous overcurrent for phase and ground feeder protection are the most common protection elements found in any coordinated protection scheme. Relay technology has changed since the days of electromechanical relays, but the fundamentals of 50/51 have not, the testing approach for these elements are the same no matter what relay technology you’re using. Abnormal conditions and overcurrent protection elements are topics discussed for prevention of equipment damage and safety. Understanding the functions of Current Transformer (CT) and Voltage Transformer (VT) ratios, polarity, and operating principles as they apply to relaying are essential and will be covered as part of relay metering labs. Various manufacturers’ relays will be used for a realistic hands-on reinforcement of classroom-taught material, along with demonstrations for the best experience and education. Review of drawings depicting how 50/51 elements are used as well as for connection validation will also be covered.

Target audience

Maintenance technicians, electricians, engineers, or any others who are responsible for maintaining a safe and reliable electrical power distribution system in an industrial or commercial facility looking for entry level relay testing experience. Sales teams can benefit with the fundamentals taught in this class to better understand customer equipment.

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Course options

In-person training

In person training 2 days, 1.5 CEUs
Locations: Various
Cost: $1,000 USD

Course topics

General information

Introduction to electromechanical and microprocessor relays.
Basic power / metering calculations.
As Found / Coordination / Testing parameters and when to use them.
CT / VT construction and connections as they appear in drawings for relaying schemes.
Relay test equipment and best practices when testing relays.
Fundamentals of phase and ground overcurrent / short circuit detection and how relays clear the condition.

Relay Types and IEEE Functions Used In This Class

ABB CO 50 / 51
GE IAC 50 / 51

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