POWER TRANSFORMERS: OPERATION, MAINTENANCE, AND TESTING

Description

This course covers the theory, operation, maintenance, and testing of power transformers and auxiliary equipment. Topics included are transformer fundamentals, transformer ratings, transformer cooling, nitrogen gas systems, and insulation systems. The source concludes with in-depth discussions of transformer testing techniques. This course is applicable to technicians and engineers who need a sound understanding of power transformer operation and maintenance. Participants will learn safe and proper maintenance and testing procedures on the pad-mounted, power transformers. The course covers transformers used in commercial and industrial power distribution systems, including oil and dry-type units. Larger power transformers used in utility applications are also covered.

Load and no-load tap changer maintenance, ac and dc testing, routine inspections, and oil sampling and testing are covered in detail. Participants will learn how to perform routine oil tests, and understand how to perform the major tests that are required. A variety of electrical test equipment from various manufacturers will be discussed.

Objectives

Upon completion of this course, the participant should be able to:

Explain the basic operation of a transformer.

Discuss turns ratios and calculate terminal voltage and current.

Discuss terminal markings and various single-phase and three-phase wiring schemes.

(WYE vs DELTA).

Explain how to perform a polarity test on a potential transformer.

Discuss the electrical testing performed on transformers such as insulation resistance

testing, excitation, and power factor testing.

Discuss the various tests performed on insulating

Outline

Transformer Principles

Transformers

Right-Hand Rule

Magnetic Flux

Magnetic Induction

Left Hand RuleTurns Ratio

Transformer Losses

Transformer Types

Vector Diagrams

Operating Principles

Operation Without Load

Operation with Load

3.  Transformer Classifications

Service Classification

Instrument Transformers

Transformer Construction (Construction)

Magnetizing Circuits

Losses

Efficiency

Cooling

Air-Cooled Oil-Immersed

Temperature Limits

Transformer Loading

Tap Changers

No-Load Tap Changer

Tap Changing Under Load

Phase-Angle Control

Transformer Connections

Single Phase Circuits

Two-Phase Circuits

Three-Phase Circuits

Transformer Maintenance

Insulation Testing

High Potential Testing

Turns Ratio Testing

Polarity Testing

Power Factor

Excitation Current

DC Winding Resistance

Polarization Recovery

Insulating Fluid Dielectric

Dissolved Gas Analysis

Transformers and Relaying

Transformer Faults

Differential Relaying