Practical Power Transformers: Operation, Maintenance & Testing

THE WORKSHOP

Installation of high voltage distribution and transmission equipment has increased significantly over the years due to ongoing global demand for power. As a result, the need to ensure the reliability of operation of power systems is paramount.

Power transformers are among the most important and most expensive components of power systems and their failure can impose extraordinarily high costs on plants, factories and utilities of all descriptions.

It is critical that all personnel operating and working with such equipment have a sound knowledge of their operational requirements and maintenance.

This practical workshop provides knowledge on both the theory and operation of power transformers. The course will develop and enhance an understanding of what is involved in the maintenance of these essential components of power systems, through the tips and tricks learnt and developed by some of the world’s pre-eminent electrical engineers.

 

WHO SHOULD ATTEND?

  • Consulting engineers
  • Electrical contractors and inspectors
  • Electrical engineers and technicians
  • Power system engineers and technicians
  • Project engineers
  • Tradesman electricians
  • Utility engineers

 

CONTENT SUMMARY

INTRODUCTION

TRANSFORMERS’ MAIN FUNCTIONS AND CLASSIFICATION

  • Construction (shell type and core type)
  • Classification and type in relation to insulation, windings, core, cooling systems, voltage level, sizing, tank and breathing action
  • Transformer parts

POWER TRANSFORMERS AND SAFETY

  • How to install, operate and work with high voltage power transformers safely
  • Earthing of HV transformers

TRANSFORMER THEORY

  • Electrical values and their definition in a power transformer - voltage, current, number of turns, impedance and their interrelation

OPERATION OF POWER TRANSFORMERS IN A POWER SYSTEM

  • Thermal performance, loading, paralleling, tap-changing, connections and vector groups

POWER TRANSFORMER PROTECTION

  • Surge protection
  • Protective relaying (differential, over-current and earth fault)
  • Buchholz relay and pressure relief relay
  • Thermal devices and instruments (oil temperature alarm and trip, winding temperature alarm and trip)

AUTO-TRANSFORMERS

  • Design criteria
  • Specifications

GENERATOR TRANSFORMERS

  • Design criteria
  • Specifications

UNIT TRANSFORMERS

  • Design criteria
  • Specifications

STATION TRANSFORMERS

  • Design criteria
  • Specifications

POWER TRANSFORMER OIL AND OIL QUALITY

  • Oil contents: water, acidity and dissolved gas
  • Oil tests: dielectric breakdown, moisture, resistivity, interfacial tension, specific gravity, power factor, furan analysis
  • Recovery voltage measurement test

POWER TRANSFORMER ELECTRICAL TESTS

AC tests:

  • Power factor tests (insulation, oil and bushings)
  • Single phase excitation current test
  • Transformer turns ratio test

DC tests:

  • Insulation resistance test
  • Dielectric absorption test
  • Polarisation index test
  • Step voltage test
  • Hi-pot test

TAPPINGS AND TAP CHANGERS

  • Uses of tap changers
  • Impedance variation
  • Tap changer mechanisms
  • On-load tap changing by reactor transition
  • Divertor resistor tap changers
    • In tank type tap changers
    • Externally mounted tap changers
  • Off-circuit tap changers
  • Construction of tap changers
  • Control of on-load tap changers
    • Master/follower control
    • Circulating current control
    • Runaway prevention
  • Moving coil regulator
  • The Brentford linear regulating transformer
  • Preventative maintenance guidelines
  • Standards applicable to tap changers C57.131-1995
  • Comparison between IEEE and IEC approaches

PRACTICAL SESSION – DESIGN EXERCISE

PREVENTATIVE MAINTENANCE ON POWER TRANSFORMERS

  • Techniques to improve life expectancy

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This course is available fully online through IDC Video: On-Demand video courses.

CLICK HERE for more information.