IEEE Std 62-1995 IEEE Guide for Diagnostic Field Testing of Electric Power Apparatus— Part 1: Oil Filled Power Transformers, Regulators, and Reactors -Description

Abstract: Diagnostic tests and measurements that are performed in the field on oil-immersed power transformers and regulators are described. Whenever possible, shunt reactors are treated :n a similar manner to transformers. Tests are presented systematically in categories depending on the subsystem of the unit being examined. A diagnostic chart is included as an aid to identify the various subsystems. Additional information is provided regarding specialized test and measuring techniques.

Keywords: Oil filled transformers, regulators, reactors, diagnostic evaluation, off-line testing, field testing, windings, bushings, insulating fluids, tapchangers, core, tanks, safety

Content

• 1. Overview
• • 1.1 Scope
• 2. References
• 3. Definitions
• 4. Diagnostic chart
• 5. Safety
• • 5.1 General
  • 5.2 Personnel
  • • 5.2.1 Hazards
    • 5.2.2 Ground connection
    • 5.2.3 Precautions
    • 5.2.4 Warning signs and barriers
    • 5.2.5 Atmosphere inside tank
  • 5.3 Apparatus
  • • 5.3.1 Consequences of failure
    • 5.3.2 Overvoltage
    • 5.3.3 Graded insulation
    • 5.3.4 Testing under vacuum
    • 5.3.5 Surge arresters
• 6. Tests and test techniques
• • 6.1 Windings
  • • 6.1.1 Winding resistance
    • 6.1.2 Ratio/polarity/phase
    • 6.1.3 Exciting current
    • 6.1.4 Short-circuit impedance
    • 6.1.5 Insulation resistance
    • 6.1.6 Capacitance, power factor, and dissipation factor
    • 6.1.7 Induced voltage test
    • 6.1.8 Partial discharge detection
  • 6.2 Bushings
  • • 6.2.1 General
    • 6.2.2 Visual inspection
    • 6.2.3 Oil level
    • 6.2.4 Capacitance, power factor, and dissipation factor
    • 6.2.5 Partial discharge (PD)
  • 6.3 Insulating fluids (transformer-grade mineral oil)
  • • 6.3.1 General
    • 6.3.2 Acidity, neutralization number (NN)
    • 6.3.3 Color
    • 6.3.4 Dielectric strength
    • 6.3.5 Dissolved gas
    • 6.3.6 Interfacial tension (IFT)
    • 6.3.7 Particle count
    • 6.3.8 Power factor
    • 6.3.9 Polychlorinated biphenyl (PCB) content
    • 6.3.10 Sludging condition
    • 6.3.11 Visual
    • 6.3.12 Water content
    • 6.3.13 Specific gravity
  • 6.4 Tap changers
  • • 6.4.1 General
    • 6.4.2 General inspection procedures for LTCs
    • 6.4.3 Specific inspection procedures for LTCs
    • 6.4.4 Tap changers for de-energized operation—general inspection procedures
    • 6.4.5 Voltage regulators
  • 6.5 Core
  • • 6.5.1 General
    • 6.5.2 Core insulation resistance and inadvertent ground tests
    • 6.5.3 Location of an inadvertent core ground
  • 6.6 Tanks and associated devices
  • • 6.6.1 General
    • 6.6.2 Conservators
    • 6.6.3 Cooling system
    • 6.6.4 Cooling system heat exchangers
    • 6.6.5 Cooling system pumps
    • 6.6.6 Fault gas detector relay—operation
    • 6.6.7 Fault pressure relay
    • 6.6.8 Flow gauge operation
    • 6.6.9 Visual inspection of liquid level gauges
    • 6.6.10 Visual calibration of pressure gauges
    • 6.6.11 Temperature gauges
• Annex A Power factor measurements
• • A.1 General
  • A.2 Ungrounded specimen test (UST)
  • A.3 Grounded specimen test (GST)
  • A.4 Grounded specimen test with guard
  • A.5 Simple and complex insulating systems
  • • A.5.1 Simple system
    • A.5.2 Complex system
• Annex B Bushings
• Annex C Infrared temperature measurements
• • C.1 General
  • C.2 IR temperature measurement

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