ANSI ® C57.12.52-1981 American National Standard Requirements for Sealed Dry-Type Power Transformers, 501 kVA and Larger, Three-Phase, with High-Voltage 601 to 34 500 Volts, Low-Voltage 208Y/120 to 4160 Volts -Description

Content

• 1. Scope
• 2. Related Standards and Guides
• • 2.1 General
  • 2.2 Terminology
  • 2.3 Revision of American National Standards Referred to in This Document
• Part I: Basic Electrical and Mechanical Requirements
• 1. Usual Service Conditions
• 2. Ratings and Characteristics
• • 2.1 Kilovolt-Ampere Ratings
  • 2.2 Kilovolt-Ampere and Voltage Ratings
  • 2.3 Taps
  • 2.4 Insulation Levels
  • 2.5 Angular Displacement and Terminal Markings
  • • 2.5.1 Angular Displacement
    • 2.5.2 External Terminal Designations
  • 2.6 Percent Impedance Voltage
• 3. Construction (See Fig. )
• • 3.1 Insulation System
  • 3.2 Accessory Location
  • 3.3 Nameplate
  • 3.4 Transformer Connections
  • 3.5 Tap Changer
  • 3.6 Temperature Indication
  • • 3.6.1 Top Gas Temperature Indicator
    • 3.6.2 Winding Temperature Simulator
  • 3.7 Pressure-Vacuum Gage
  • 3.8 Shutoff Valve
  • 3.9 Filling Valve
  • 3.10 Tank
  • • 3.10.1 Tank Sealing
    • 3.10.2 Tank Pressure and Vacuum
    • 3.10.3 Lifting, Jacking, and Moving Facilities
    • 3.10.4 Ground Pad
• 4. Routine Tests
• 5. Tolerances
• Part II: Other Requirements or Alternatives That May Be Specified for Some Applications
• 1. Other Ratings and Characteristics
• • 1.1 Other Ambient Temperature Conditions
  • • 1.1.1 40°C Average Ambient Temperature Conditions
    • 1.1.2 Other Minimum Ambient Temperature Conditions
  • 1.2 Other Winding Temperature Rises
  • 1.3 Other Insulation Systems
  • 1.4 Other High-Voltage Ratings and Connections
  • • 1.4.1 High-Voltage Windings without Taps
    • 1.4.2 Other High-Voltage Ratings
    • 1.4.3 Y-Connected High-Voltage Windings with Δ-Connected Low-Voltage Windings
  • 1.5 Y-Y Connected Transformers
  • • 1.5.1 Kilovolt-Ampere, Voltage, and BIL Combinations
    • 1.5.2 Unsymmetrical Excitation or Loading
    • 1.5.3 Angular Displacement of Y–Y Connected Transformers
    • 1.5.4 Neutral Connections
  • 1.6 Increased Neutral Insulation
  • 1.7 Other Basic Lightning Impulse Insulation Levels (BILs)
• 2. Other Construction (See Fig. )
• • 2.1 High-Voltage Connection Arrangements
  • 2.2 Low-Voltage Connection Arrangements
  • 2.3 Surge Arresters
  • 2.4 Unit Substation Application
  • 2.5 Pressure Alarm Switch
  • 2.6 High-Temperature Alarm Switch
  • 2.7 Current Transformers (or Provision for Their Addition in the Future)
  • 2.8 Terminal Blocks
  • 2.9 Contacts
• 3. Other Tests

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