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  • IEEE C57.91:2011

    Current The latest, up-to-date edition.

    GUIDE FOR LOADING MINERAL-OIL-IMMERSED TRANSFORMERS AND STEP-VOLTAGE REGULATORS

    Available format(s):  Hardcopy, PDF

    Language(s):  English

    Published date:  01-03-2012

    Publisher:  Institute of Electrical & Electronics Engineers

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    Table of Contents - (Show below) - (Hide below)

    1. Overview
    2. Normative references
    3. Definitions
    4. Effect of loading beyond nameplate rating
    5. Transformer insulation life
    6. Ambient temperature and its influence on loading
    7. Calculation of temperatures
    8. Loading of distribution transformers and step-voltage
       regulators
    9. Loading of power transformers
    Annex A (normative) - Thermal evolution of gas from
            transformer insulation
    Annex B (normative) - Effect of loading transformers above
            nameplate rating on bushings, tap changers, and
            auxiliary components
    Annex C (informative) - Calculation methods for determining
            ratings and selecting transformer size
    Annex D (normative) - Philosophy of guide applicable to
            transformers with 55 degrees C average winding rise
            (65 degrees C hottest-spot rise) insulation systems
    Annex E (normative) - Unusual temperature and altitude
            conditions
    Annex F (normative) - Cold-load pickup (CLPU)
    Annex G (informative) - Alternate temperature calculation
            method
    Annex H (normative) - Operation with part or all of the
            cooling out of service
    Annex I (informative) - Transformer insulation life

    Abstract - (Show below) - (Hide below)

    This guide provides recommendations for loading mineral-oil-immersed transformers and step-voltage regulators with insulation systems rated for a 65 °C average winding temperature rise at rated load.

    General Product Information - (Show below) - (Hide below)

    Development Note Supersedes IEEE DRAFT C57.91, IEEE C57.92 and IEEE C57.115. (08/2004)
    Document Type Standard
    Publisher Institute of Electrical & Electronics Engineers
    Status Current
    Supersedes

    Standards Referenced By This Book - (Show below) - (Hide below)

    IEEE C57.12.10-2010 STANDARD REQUIREMENTS FOR LIQUID-IMMERSED POWER TRANSFORMERS
    IEEE C57.105-1978 IEEE GUIDE FOR THE APPLICATION OF TRANSFORMER CONNECTIONS IN THREE-PHASE DISTRIBUTION SYSTEMS
    PD IEC/TR 62874:2015 Guidance on the interpretation of carbon dioxide and 2-furfuraldehyde as markers of paper thermal degradation in insulating mineral oil
    ANSI C57.12.10 : 2010 TRANSFORMERS - 230 KV AND BELOW 833/958 THROUGH 8333/10 417 KVA, SINGLE-PHASE, AND 750/862 THROUGH 60 000/80 000/100 000 KVA, THREE-PHASE WITHOUT LOAD TAP CHANGING; AND 3750/4687 THROUGH 60 000/80 000/100 000 KVA WITH LOAD TAP CHANGING - SAFETY REQUIREMENT
    IEEE 1653.3 : 2012 GUIDE FOR RAIL TRANSIT TRACTION POWER SYSTEMS MODELING
    CEI 14-43 : 2011 GUIDE FOR THE APPLICATION, SPECIFICATION, AND TESTING OF PHASE-SHIFTING TRANSFORMERS
    CEI EN 60076-14 : 2014 POWER TRANSFORMERS - PART 14: LIQUID-IMMERSED POWER TRANSFORMERS USING HIGH-TEMPERATURE INSULATION MATERIALS
    IEEE C57.12.38 : 2014 PAD-MOUNTED-TYPE, SELF-COOLED, SINGLE-PHASE DISTRIBUTION TRANSFORMERS 250 KVA AND SMALLER: HIGH VOLTAGE, 34 500 GRDY/19 920 V AND BELOW; LOW VOLTAGE, 480/240 V AND BELOW
    IEEE C57.154-2012 DESIGN, TESTING, AND APPLICATION OF LIQUID-IMMERSED DISTRIBUTION, POWER, AND REGULATING TRANSFORMERS USING HIGH-TEMPERATURE INSULATION SYSTEMS AND OPERATING AT ELEVATED TEMPERATURES
    IEEE C57.32 : 2015 REQUIREMENTS, TERMINOLOGY, AND TEST PROCEDURES FOR NEUTRAL GROUNDING DEVICES
    IEC TR 62874:2015 Guidance on the interpretation of carbon dioxide and 2-furfuraldehyde as markers of paper thermal degradation in insulating mineral oil
    I.S. EN 60076-14:2013 POWER TRANSFORMERS - PART 14: LIQUIDIMMERSED POWER TRANSFORMERS USING HIGH-TEMPERATURE INSULATION MATERIALS (IEC 60076-14:2013 (EQV))
    IEEE DRAFT C57.12.21 : D12 MAY 92 DRAFT REQUIREMENTS FOR PAD-MOUNTED, COMPARTMENTAL-TYPE, SELF-COOLED, SINGLE-PHASE DISTRIBUTION TRANSFORMERS WITH HIGH VOLTAGE BUSHINGS; HIGH VOLTAGE, 34500 GRDY/19920 VOLTS AND BELOW; LOW VOLTAGE, 240/120 VOLTS; 16 KVA AND SMALLER
    CSA C2 : 0 SINGLE-PHASE AND THREE-PHASE DISTRIBUTION TRANSFORMERS, TYPES ONAN AND LNAN
    IEEE C57.110 : 2008 ESTABLISHING LIQUID-FILLED AND DRY-TYPE POWER AND DISTRIBUTION TRANSFORMER CAPABILITY WHEN SUPPLYING NONSINUSOIDAL LOAD CURRENTS
    IEEE C37.48.1-2002 GUIDE FOR THE APPLICATION, OPERATION, AND COORDINATION OF HIGH-VOLTAGE (>1000 V) CURRENT-LIMITING FUSES
    EN 60076-2:2011 Power transformers - Part 2: Temperature rise for liquid-immersed transformers
    BS EN 60076-2:2011 Power transformers Temperature rise for liquid-immersed transformers
    BS EN 60076-14:2013 Power transformers Liquid-immersed power transformers using high-temperature insulation materials
    IEEE C57.109-1993 GUIDE FOR LIQUID-IMMERSED TRANSFORMER THROUGH-FAULT-CURRENT DURATION
    UNE-EN 60076-14:2014 Power transformers - Part 14: Liquid-immersed power transformers using high-temperature insulation materials
    CSA C227.3 : 2006 LOW-PROFILE, SINGLE-PHASE, PAD-MOUNTED DISTRIBUTION TRANSFORMERS WITH SEPARABLE INSULATED HIGH-VOLTAGE CONNECTORS
    CSA C227.5 : 2008 : R2013 THREE-PHASE LIVE-FRONT PAD-MOUNTED DISTRIBUTION TRANSFORMERS
    IEEE 1031 : 2011 GUIDE FOR THE FUNCTIONAL SPECIFICATION OF TRANSMISSION STATIC VAR COMPENSATORS
    IEEE C57.143:2012 GUIDE FOR APPLICATION FOR MONITORING EQUIPMENT TO LIQUID-IMMERSED TRANSFORMERS AND COMPONENTS
    ANSI C57.12.24 : 2009 TRANSFORMERS - UNDERGROUND-TYPE THREE-PHASE DISTRIBUTION TRANSFORMERS, 2500 KVA AND SMALLER; HIGH VOLTAGE, 34 500 GRDY/19 920 VOLTS AND BELOW; LOW VOLTAGE, 480 VOLTS AND BELOW - REQUIREMENTS
    IEC 60076-7:2018 Power transformers - Part 7: Loading guide for mineral-oil-immersed power transformers
    NEMA TR1 : 2013 TRANSFORMERS, STEP VOLTAGE REGULATORS AND REACTORS
    CEI EN 60076-2 : 2015 POWER TRANSFORMERS - PART 2: TEMPERATURE RISE FOR LIQUID-IMMERSED TRANSFORMERS
    IEEE C57.15 : 2009 REQUIREMENTS, TERMINOLOGY, AND TEST CODE FOR STEP-VOLTAGE REGULATORS
    IEEE DRAFT C57.12.23 : 1992 TRANSFORMERS - UNDERGROUND-TYPE, SELF-COOLED, SINGLE-PHASE DISTRIBUTION TRANSFORMERS WITH SEPARABLE, INSULATED, HIGH-VOLTAGE CONNECTORS; HIGH VOLTAGE (24 940 GRDY/14 400 V AND BELOW) AND LOW VOLTAGE (240/120 V, 167 KVA AND SMALLER)
    IEEE C57.157 : 2015 GUIDE FOR CONDUCTING FUNCTIONAL LIFE TESTS ON SWITCH CONTACTS USED IN INSULATING LIQUID-IMMERSED TRANSFORMERS
    IEEE C57.131-2012 REDLINE IEEE Standard Requirements for Tap Changers
    IEEE C57.152 : 2013 GUIDE FOR DIAGNOSTIC FIELD TESTING OF FLUID-FILLED POWER TRANSFORMERS, REGULATORS, AND REACTORS
    IEEE C57.100:2011 THERMAL EVALUATION OF INSULATION SYSTEMS FOR LIQUID-IMMERSED DISTRIBUTION AND POWER TRANSFORMERS
    IEEE DRAFT 1276 : D6.0 DEC 96 DRAFT TRIAL USE GUIDE FOR THE APPLICATION OF HIGH TEMPERATURE INSULATION MATERIALS IN LIQUID-IMMERSED POWER TRANSFORMERS
    IEEE 1861 : 2014 GUIDE FOR ON-SITE ACCEPTANCE TESTS OF ELECTRICAL EQUIPMENT AND SYSTEM COMMISSIONING OF 1000 KV AC AND ABOVE
    IEEE C57.12.39 : 2017 REQUIREMENTS FOR DISTRIBUTION TRANSFORMER TANK PRESSURE COORDINATION
    IEEE DRAFT C37.91 : D7.0 2006 PROTECTING POWER TRANSFORMERS
    CSA C227.4 : 2006 THREE-PHASE, PAD-MOUNTED DISTRIBUTION TRANSFORMERS WITH SEPARABLE INSULATED HIGH-VOLTAGE CONNECTORS
    IEEE 638 : 2013 QUALIFICATION OF CLASS 1E TRANSFORMERS FOR NUCLEAR POWER GENERATING STATIONS
    IEEE C57.12.24 : 2009 SUBMERSIBLE, THREE-PHASE TRANSFORMERS, 3750 KVA AND SMALLER: HIGH VOLTAGE, 34500 GRDY/19920 VOLTS AND BELOW; LOW VOLTAGE, 600 VOLTS AND BELOW
    CSA C2.1 : 2006 SINGLE-PHASE AND THREE-PHASE LIQUID-FILLED DISTRIBUTION TRANSFORMERS
    ANSI C57.12.40 : 2011 AMERICAN NATIONAL STANDARD FOR SECONDARY NETWORK TRANSFORMERS - SUBWAY AND VAULT TYPES (LIQUID IMMERSED) - REQUIREMENTS
    CAN/CSA-C2.1-06 (R2017) Single-Phase and Three-Phase Liquid-Filled Distribution Transformers
    IEC/IEEE 60076-57-129:2017 Power transformers - Part 57-129: Transformers for HVDC applications
    IEEE C57.12.23 : 2009 SUBMERSIBLE SINGLE-PHASE TRANSFORMERS: 167 KVA AND SMALLER; HIGH VOLTAGE 25000 V AND BELOW; LOW VOLTAGE 600 V AND BELOW
    BS IEC 60076-21:2011 Power transformers Standard requirements, terminology, and test code for step-voltage regulators
    IEEE DRAFT C57.135 : D12 AUG 2000 DRAFT GUIDE FOR THE APPLICATION, SPECIFICATION AND TESTING OF PHASE-SHIFTING TRANSFORMERS
    IEEE C57.12.36 : 2007 REQUIREMENTS FOR LIQUID-IMMERSED DISTRIBUTION SUBSTATION TRANSFORMERS
    IEC 60076-21:2011 Power transformers - Part 21: Standard requirements, terminology, and test code for step-voltage regulators
    IEC 62032:2012 Guide for the Application, Specification and Testing of Phase-Shifting Transformers
    IEEE 242 : 2001 PROTECTION AND COORDINATION OF INDUSTRIAL AND COMMERCIAL POWER SYSTEMS
    IEEE 3001.5 : 2013 RECOMMENDED PRACTICE FOR THE APPLICATION OF POWER DISTRIBUTION APPARATUS IN INDUSTRIAL AND COMMERCIAL POWER SYSTEMS
    IEEE 1818 : 2017 GUIDE FOR THE DESIGN OF LOW-VOLTAGE AUXILIARY SYSTEMS FOR ELECTRIC POWER SUBSTATIONS
    IEEE 1276 : 1997 TRIAL-USE GUIDE FOR THE APPLICATION OF HIGH TEMPERATURE INSULATION MATERIALS IN LIQUID-IMMERSED POWER TRANSFORMERS
    CEI 14-15 : 2006 POWER TRANSFORMERS - PART 7: LOADING GUIDE FOR OIL-IMMERSED POWER TRANSFORMERS
    IEEE C57.12.44 : 2014 REQUIREMENTS FOR SECONDARY NETWORK PROTECTORS
    IEEE C57.163 : 2015 GUIDE FOR ESTABLISHING POWER TRANSFORMER CAPABILITY WHILE UNDER GEOMAGNETIC DISTURBANCES
    CAN/CSA-C227.3-06 (R2017) Low-profile, single-phase, pad-mounted distribution transformers with separable insulated high-voltage connectors
    CSA C2.2:2006 : R2011 POLE-MOUNTED, SINGLE-PHASE DISTRIBUTION TRANSFORMERS FOR ELECTRIC UTILITIES
    IEEE C57.92-1981 IEEE Guide for Loading Mineral-Oil-Immersed Power Transformers Up to and Including 100 MVA with 55 C or 65 C Average Winding Rise
    UNE-IEC 60076-7:2010 Power transformers - Part 7: Loading guide for oil-immersed power transformers
    CSA C227.4 : 2006 : R2017 THREE-PHASE, PAD-MOUNTED DISTRIBUTION TRANSFORMERS WITH SEPARABLE INSULATED HIGH-VOLTAGE CONNECTORS
    IEEE C57.140 : 2006 EVALUATION AND RECONDITIONING OF LIQUID IMMERSED POWER TRANSFORMERS
    IEEE C57.159:2016 IEEE GUIDE ON TRANSFORMERS FOR APPLICATION IN DISTRIBUTED PHOTOVOLTAIC (DPV) POWER GENERATION SYSTEMS
    CSA C227.3 : 2006 : R2011 LOW-PROFILE, SINGLE-PHASE, PAD-MOUNTED DISTRIBUTION TRANSFORMERS WITH SEPARABLE INSULATED HIGH-VOLTAGE CONNECTORS
    I.S. EN 60076-2:2011 POWER TRANSFORMERS - PART 2: TEMPERATURE RISE FOR LIQUID-IMMERSED TRANSFORMERS
    IEEE C37.91 : 2008 PROTECTING POWER TRANSFORMERS
    IEEE C37.121-2012 GUIDE FOR SWITCHGEAR - UNIT SUBSTATION - REQUIREMENTS
    IEEE C57.12.40 : 2011 NETWORK, THREE-PHASE TRANSFORMERS, 2500 KVA AND SMALLER; HIGH VOLTAGE, 34500 V AND BELOW; LOW VOLTAGE, 600 V AND BELOW; SUBWAY AND VAULT TYPES (LIQUID IMMERSED)
    IEEE C57.12.34-2015 REDLINE IEEE Standard Requirements for Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase Distribution Transformers, 10 MVA and Smaller; High-Voltage, 34.5 kV Nominal System Voltage and Below; Low-Voltage, 15 kV Nominal System Voltage and Below
    ANSI C57.12.20 : 2011 TRANSFORMERS - STANDARD FOR OVERHEAD TYPE DISTRIBUTION TRANSFORMERS, 500 KVA AND SMALLER: HIGH VOLTAGE, 34500 VOLTS AND BELOW: LOW VOLTAGE, 7970/13800Y VOLTS AND BELOW
    IEEE 1147 : 2005 GUIDE FOR THE REHABILITATION OF HYDROELECTRIC POWER PLANTS
    IEC 60076-2:2011 Power transformers - Part 2: Temperature rise for liquid-immersed transformers
    UNE-EN 60076-2:2013 Power transformers - Part 2: Temperature rise for liquid-immersed transformers
    IEC 60076-14:2013 Power transformers - Part 14: Liquid-immersed power transformers using high-temperature insulation materials
    IEEE C57.12.00-2015 STANDARD FOR GENERAL REQUIREMENTS FOR LIQUID-IMMERSED DISTRIBUTION, POWER, AND REGULATING TRANSFORMERS
    IEEE C57.19.100-2012 REDLINE IEEE Guide for Application of Power Apparatus Bushings
    IEEE DRAFT C57.12.22 : D4 JUL 93 PAD-MOUNTED, COMPARTMENTAL-TYPE, SELF COOLED THREE PHASE DISTRIBUTION TRANSFORMERS WITH HIGH-VOLTAGE BUSHINGS, 2500 KVA AND SMALLER: HIGH VOLTAGE, 34 500 GRDY/19 920 VOLTS AND BELOW; LOW VOLTAGE, 480 VOLTS AND BELOW
    IEEE C57.119-2001 RECOMMENDED PRACTICE FOR PERFORMING TEMPERATURE RISE TESTS ON OIL-IMMERSED POWER TRANSFORMERS AT LOADS BEYOND NAMEPLATE RATINGS
    CSA C2.1 : 2006 : R2011 SINGLE-PHASE AND THREE-PHASE LIQUID-FILLED DISTRIBUTION TRANSFORMERS
    CSA C2.2 : 2006 POLE-MOUNTED, SINGLE-PHASE DISTRIBUTION TRANSFORMERS FOR ELECTRIC UTILITIES
    CSA C227.5:2008 THREE-PHASE LIVE-FRONT PAD-MOUNTED DISTRIBUTION TRANSFORMERS
    CAN/CSA-C2.2-06 (R2017) Pole-Mounted, Single-Phase Distribution Transformers for Electric Utilities
    CSA C227.4 : 2006 : R2011 THREE-PHASE, PAD-MOUNTED DISTRIBUTION TRANSFORMERS WITH SEPARABLE INSULATED HIGH-VOLTAGE CONNECTORS
    C88-16 Power transformers and reactors
    ANSI C37.121 : 2012 AMERICAN NATIONAL STANDARD FOR SWITCHGEAR - UNIT SUBSTATIONS - REQUIREMENTS
    IEEE C57.135 : 2011 GUIDE FOR THE APPLICATION, SPECIFICATION, AND TESTING OF PHASE-SHIFTING TRANSFORMERS
    IEEE C57.125:2015 GUIDE FOR FAILURE INVESTIGATION, DOCUMENTATION, ANALYSIS, AND REPORTING FOR POWER TRANSFORMERS AND SHUNT REACTORS
    EN 60076-14:2013 Power transformers - Part 14: Liquid-immersed power transformers using high-temperature insulation materials

    Standards Referencing This Book - (Show below) - (Hide below)

    IEEE C57.19.100-2012 REDLINE IEEE Guide for Application of Power Apparatus Bushings
    IEC 60214:1989 On-load tap-changers
    IEEE C57.12.00-2015 STANDARD FOR GENERAL REQUIREMENTS FOR LIQUID-IMMERSED DISTRIBUTION, POWER, AND REGULATING TRANSFORMERS
    IEC 60354:1991 Loading guide for oil-immersed power transformers
    IEEE C57.15 : 2009 REQUIREMENTS, TERMINOLOGY, AND TEST CODE FOR STEP-VOLTAGE REGULATORS
    IEEE C57.12.90-2010 LIQUID-IMMERSED DISTRIBUTION, POWER, AND REGULATING TRANSFORMERS
    IEEE C57.100:2011 THERMAL EVALUATION OF INSULATION SYSTEMS FOR LIQUID-IMMERSED DISTRIBUTION AND POWER TRANSFORMERS
    ASTM D 5222 : 2016 : REDLINE Standard Specification for High Fire-Point Mineral Electrical Insulating Oils
    IEEE C57.119-2001 RECOMMENDED PRACTICE FOR PERFORMING TEMPERATURE RISE TESTS ON OIL-IMMERSED POWER TRANSFORMERS AT LOADS BEYOND NAMEPLATE RATINGS
    IEEE C57.131-2012 REDLINE IEEE Standard Requirements for Tap Changers
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