Megger TTR25 Instruction Manual
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Megger TTR25 Instruction Manual

Hand-held transformer turns ratio tester
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AVTMTTR25
Rev. C
April 2008
Instruction Manual AVTMTTR25
for
®
TTR25 Handheld TTR
Transformer Turn Ratio Test Set
Catalog No. TTR25
High-Voltage Equipment
Read the entire manual before operating.
Aparato de Alto Voltaje
Antes de operar este producto lea este manual enteramente.
M
2621 Van Buren Ave
Norristown, PA 19403-2329
610-676-8500
www.megger.com

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  • Page 1 AVTMTTR25 Rev. C April 2008 Instruction Manual AVTMTTR25 ® TTR25 Handheld TTR Transformer Turn Ratio Test Set Catalog No. TTR25 High-Voltage Equipment Read the entire manual before operating. Aparato de Alto Voltaje Antes de operar este producto lea este manual enteramente.
  • Page 3 ® TTR25 Handheld TTR Transformer Turn Ratio Test Set Instruction Manual...
  • Page 4 If the product or its individual instrument are used for purposes other than those specified herein, confirmation of their validity and suitability must be obtained from Megger. Refer to the warranty information included at the end of this instruction manual. Specifications are subject to change without notice.

  • Page 5: Table Of Contents

    ......................... 1 NTRODUCTION About the TTR25......................1 Electrical Theory and Practice ................... 2 Applications for the TTR25 ..................4 Upon Receipt of the TTR25 ..................5 Safety First......................... 5 How to Use This Manual.................... 5 ........................... 7 AFETY Overview........................7 Safety Requirements ....................
  • Page 6 TTR25 Functional Test .................... 28 Battery Replacement ....................29 Troubleshooting ....................... 30 Error Messages......................31 Repair ........................33 A - S ....................35 PPENDIX PECIFICATIONS Electrical ........................35 Environmental Conditions ..................37 Physical Data ......................37 Optional Accessories ....................38 B - O &...
  • Page 7 LIST OF ILLUSTRATIONS Figure 1-1. TTR25 Single-Phase Test Set Block Diagram ............. 4 Figure 3-1 TTR25 Display & Control Panel ................9 Figure 3-2 TTR25 Top Side Connector Panel ..............10 Figure 4-1 Setup for Testing Single-Phase Transformer ............. 13 Figure 4-2 Setup for Testing Single-Phase Autotransformer ..........
  • Page 8 LIST OF TABLES ..................30 ABLE ROUBLESHOOTING UIDE ................31 ABLE TEST RROR ESSAGES ..................31 ABLE RROR ESSAGES ..................32 ABLE ISCELLANEOUS ESSAGE ANSI T ..........42 ABLE RANSFORMER INDING HASE ELATIONSHIP ANSI T ..........44 ABLE RANSFORMER INDING HASE ELATIONSHIP CEI/IEC 76-1:1993 T...

  • Page 9: Introduction

    INTRODUCTION About the TTR25 ® The TTR25 Handheld TTR Test Set is a fully automatic, self-checking, self- calibrating unit. The test set measures the turn ratio, excitation current, and phase displacement (polarity) of single- and three-phase (phase by phase) distribution transformers, as well as power, potential and current transformers.

  • Page 10: Electrical Theory And Practice

    Electrical Theory and Practice How the TTR25 Works The TTR25 test set provides the excitation voltage to the input of the transformer. It accurately measures both the H-side and X-side voltages to calculate turns ratio. The TTR also measures phase displacement (polarity) between primary and secondary windings of a transformer, and transformer excitation current.
  • Page 11 The Megger TTR25 will identify normal (in phase) and reverse polarity of the single-phase transformers. A block diagram of TTR25 is shown in Figure 1-1. The excitation voltage oscillator applies a 55-Hz test voltage to a transformer under test. There are three test voltages: 0.5 V, 1.5 V, and 8 V used for transformer testing.

  • Page 12: Applications For The Ttr25

    It is used to determine the no-load accuracy of CTs and PTs and also determine the need to further test faulty CTs and PTs. The TTR25 applies voltage to the high-voltage winding of a transformer and accurately measures the resulting voltage from the low voltage winding. The ratio of voltages is directly proportional to turns ratio.

  • Page 13: Upon Receipt Of The Ttr25

    Notify Megger of any shortage. Telephone 610-676-8500. Examine the instrument for damage received in transit. If any damage is discovered, file a claim with the carrier at once and notify Megger or its nearest authorized sales representative, giving a detailed description of the damage.
  • Page 14 AVTMTTR25 Rev C April 2008...

  • Page 15: Safety

    Safety Requirements Megger has made formal safety reviews of the initial design and any subsequent changes. This procedure is followed for all new products and covers areas in addition to those included in applicable standards. Regardless of these efforts, it is not possible to eliminate all hazards from electrical test equipment.

  • Page 16: Cautions And Warnings

    Megger considers this an excellent safety practice. Users of equipment should note that high-voltage discharges and other sources of strong electric or magnetic field may interfere with the proper functioning of heart pacemakers.

  • Page 17: Controls & Connectors

    CONTROLS & CONNECTORS Overview The TTR25 is a simple, push-to-test instrument with few buttons and controls. It has no menus except for a print button and language selection. Contrast This knob adjusts the viewing resolution of the screen. Backlight A momentary depression of the switch will either activate or de-activate the backlight.

  • Page 18: Connectors

    Connectors PRINTER TEST CABLE Figure 3-2 TTR25 Top Side Connector Panel TEST CABLE Plug receptacle for connecting test leads to the high-voltage (H) and low-voltage (X) windings of a transformer. The plug and receptacle are keyed to prevent the cable from being inserted incorrectly, and to make certain that the correct cable is used.

  • Page 19: Setup, Connections And Operation

    Check that a lead set connected is labeled for TTR25 test set operation. The TTR25 has been designed to test a variety of transformers, such as: Single phase, Three phase (one phase at a time), CTs, PTs and Voltage Regulators.

  • Page 20: Single-Phase, Two-Winding Transformers

    The TTR25 may supply up to 100 mA of excitation current. The TTR25 will automatically select the appropriate test voltage (8 V, 1.5 V, or 0.5 V) when testing transformers. Single-Phase, Two-Winding Transformers Perform the following setup procedure for single-phase, two-winding transformers: 1.

  • Page 21: Figure 4-1 Setup For Testing Single-Phase Transformer

    X2 transformer terminal before starting the test. Expect that polarity of the windings is normal (“+” sign is displayed in front of the turns ratio test result). See Figure 4-7. TTR25 Figure 4-1 Setup for Testing Single-Phase Transformer TTR25 Figure 4-2 Setup for Testing Single-Phase Autotransformer...

  • Page 22: Figure 4-3 Setup For Testing Single-Phase, Type A Step Voltage Regulator

    TTR25 Figure 4-3 Setup for Testing Single-Phase, Type A (Straight Design) Step Voltage Regulator TTR25 Figure 4-4 Setup for Testing Single-Phase, Type B (Inverted Design) Step Voltage Regulator AVTMTTR25 Rev C April 2008...

  • Page 23: Figure 4-5 Setup For Testing X1 - X2 Winding Of Distribution Transformer

    Setup, Connections & Operation H1 LEAD X1 LEAD TTR25 X2 LEAD H2 LEAD Figure 4-5 Setup for Testing X1 – X2 Winding of Distribution Transformer (H2 and X2 Grounded) H1 LEAD X2 LEAD TTR25 X1 LEAD H2 LEAD Figure 4-6 Setup for Testing X3 – X2 Winding of Distribution Transformer...

  • Page 24: Three-Phase, Two-Winding Transformers

    Three-Phase, Two-Winding Transformers Perform the following setup procedure for three-phase, two-winding transformers: 1. Connect the test cables to the test set. 2. Connect the clips marked H1 and H2 of the test lead to the phase being tested (high-voltage winding) terminals of the transformer under test. 3.

  • Page 25: Current Transformers (Cts)

    V) when testing CTs. Some current transformers with turn ratio of 50:5 and less may require more than 100 mA of excitation current when excited from 0.5 V source. These CTs can not be tested with the TTR25. Expect that polarity of the windings is normal (“+” sign is displayed in front of the turns ratio test result).

  • Page 26: Figure 4-8 Setup For Testing Unmounted Current Transformer

    Figure 4-8 Setup for Testing Unmounted Current Transformer TTR 25 Figure 4-9 Setup for Testing Taps on Multiple Tap CT AVTMTTR25 Rev C April 2008...

  • Page 27: Figure 4-10 Setup For Testing Bct Mounted On Single-Phase Two-Winding Transformer

    A turn-ratio test can be performed on a BCT after it has been mounted on a circuit breaker or power transformer entrance bushing. The test can be performed without removal of the BCT from the equipment. Connect the TTR25 to BCT as shown in Figure 4-10.

  • Page 28: General Operating Procedure

    Data shown on the menus and test screens in Figures 4-11 through 4-14 are for illustrative purposes only. The TTR25 test set menus and test screens are operated by using the keypad. On power up, the test set performs a self-test check, and all hardware and software variables are initialized.

  • Page 29: Figure 4-12 Start Test Screen

    If battery level is below 5%, the message “REPLACE BATTERY! UNIT WILL TURN OFF” appears on the screen. In 10 sec. the TTR25 shuts down. Replace the batteries (six AA-size replaceable alkaline batteries) before further attempting to initiate the TTR25 operation.

  • Page 30: Figure 4-13 Test In Progress Screen

    If during testing an abnormal condition is detected, one of the error messages listed in the ERROR MESSAGES section is displayed on the screen. In case of emergency, press the red button on keypad. It will turn TTR25 OFF. After emergency situation is gone, turn power ON (green button) to start TTR25 operation.

  • Page 31: Use With The Optional Printer

    If you are using the optional printer, plug the printer cable supplied into the RS232/PRINTER receptacle on the TTR25 test set and turn it on. A separate manual is supplied with the printer. Refer to it for specific information about how to connect, operate, and care for the printer.

  • Page 32: Figure 4-16 Printer Configuration Printout

    Configuration To print a paper copy of the existing printer settings: While holding down the "On-Line" switch, turn on the printer. The following list will print (factory default settings shown). Figure 4-16 Printer Configuration Printout AVTMTTR25 Rev C April 2008...

  • Page 33: Hyperterminal Configuration

    Setup, Connections & Operation If you want to leave the settings as they are, press the "FEED" switch. If you need to change a setting, press the "ON LINE" switch to enter the reconfiguration mode. For each group of switches, press the "FEED" switch if all the settings are okay.
  • Page 34 AVTMTTR25 Rev C April 2008...

  • Page 35: Maintenance And Troubleshooting

    As a result of such calibration procedure, each TTR25 may be NIST certified. To check the TTR25 calibration at a customer site or in the field, the Megger Calibration Standard Cat.No550055 or equivalent standard should be used. To perform a quick simplified calibration check, the Megger Calibration Standard CatNo550555 may be used.

  • Page 36: Ttr25 Functional Test

    Additionally, the displayed test results were interpreted as a test set calibration check. TTR25 test set is designed and optimized for the transformer turns ratio testing. It uses a mixed analog-digital technique to provide the accurate readings of the tested transformer turns ratio.

  • Page 37: Battery Replacement

    5. Replace the battery compartment door and secure it with screws. 6. Turn on TTR25. It should display the opening screen, then the battery level screen. The battery level displayed depends on many factors including type of battery installed, battery manufacturing date, battery storing conditions, etc.

  • Page 38: Troubleshooting

    Troubleshooting The Troubleshooting Guide, Table 5-1, is arranged to help you evaluate the reasons for TTR25 test set malfunction. The table lists possible TTR25 test set malfunctions which may be encountered during operation and lists possible causes. Electronic circuit repairs should not be attempted in the field. Refer to Repair section.

  • Page 39: Error Messages

    Maintenance and Troubleshooting Error Messages All TTR25 error messages are divided by 3 categories: self-test error messages, test error messages, and miscellaneous error messages. The self-test error messages may appear on the opening screen during power-up self-test procedure. The Table 5-2 below shows the messages.
  • Page 40 Error Message Description of error and action required CONNECTIONS H and X test lead connections are reversed. REVERSED Connect H and X test leads properly. TURN RATIO >20,000 The tested turns ratio is higher than 20,000:1. Causes test to stop. Check for bad or open test lead connections.

  • Page 41: Repair

    Maintenance and Troubleshooting Repair Megger offers a complete repair and calibration service and recommends that its customers take advantage of this service in the event of equipment malfunction. Contact your Megger representative for instructions and a return authorization (RA) number. Equipment returned for repair should be shipped prepaid and insured and marked for the attention of the Repair Department.
  • Page 42 AVTMTTR25 Rev C April 2008...

  • Page 43: Appendixa - Specifications

    12 hrs of continuous field operation when new Energizer X91 batteries or equivalent (with average capacity of 3135 mAh) are used Pollution Degree TTR25 is designed for Pollution Degree II Regulatory Compliance IEC 61010-1 Environmental Protection Dust and shower protection to IP54 Output Test Voltage and Current 3 test voltages, automatically selected: 8V rms, 1.5V rms or 0.5V rms...
  • Page 44 Measuring Ranges Turn ratio: 0.8:1 to 20,000:1, 5 digit resolution Current: 0 to 100 mA, 4 digit resolution Transformer Polarity: NORMAL (in phase) or REVERSE (out of phase) Accuracy Turn ratio: ±0.1% (0.8 to 2000) ±0.15% (2001 to 4000) ±0.25% (4001 to 10,000) ±0.50% (10,001 to 20,000) Current (rms): ±(2% of reading + 1 digit) Measurement Method...

  • Page 45: Environmental Conditions

    Printer port: DB-9 male connector Cable used: 9-pin D-type connectors, standard extension female-female RS232 cable (for TTR25 to a PC connection. The cable is not included in accessory supplied); 9-pin D-type connectors, null modem female-male RS232 cable (for the optional serial printer connection.

  • Page 46: Optional Accessories

    IEC, and Australian Standards. Additional printer paper, one roll, (p/n 26999) USB Serial Adapter (p/n 35871) for connecting a TTR25 RS232 port to a PC USB port. The adapter is used if a PC does not have an RS232 port.

  • Page 47: Appendixb - Ordering Information & Spare Parts List

    TTR25 Included Accessories Canvas carrying bag and Accessory Pouch 55-20008 Battery ( six AA-size replaceable alkaline batteries included) 35956 TTR25 Lead Set, 1.8 m (6 ft) 35938 Instruction manual AVTMTTR25 Optional Accessories Battery/line-powered, serial, thermal-printer package, 120 V ac 35755-1...
  • Page 48 Battery door 55-20003 Knob, CONTRAST 55-20004 Battery replacement (six required) 35956 TTR25 Lead Set, 1.8 m (6 ft) 35938 TTR25 Lead Set, 3.6 m (12 ft) 35942 TTR25 Lead Set, 6 m (20 ft) 36013 TTR25 Lead Set, 10 m (33 ft)

  • Page 49: Appendixc - Connections And Vector Voltage Diagrams

    C-4 shows winding diagrams for power transformers marked in accordance with the Australian standard. To make a measurement on a three-phase power transformer with TTR25 test set, match the vector diagram from the transformer nameplate to the corresponding winding connection diagram from Table C-2 through C-4. Then connect the TTR25 test leads to the appropriate transformer winding terminals of phase A.
  • Page 50 To make a measurement on a T-type transformer, the jumpers indicated in Table C-1 should be applied to the appropriate terminals of the T-type transformer. The TTR25 measured turns ratio should be compared to the calculated turns ratio indicated in Table C-1.
  • Page 51 Appendix C Notes to Table C-2 Transformer terminal markings for distribution and power transformers marked in accordance with requirements of American National Standard Institute, Inc (ANSI) standard C57.12.70 – 1978. Definition of Symbol Designations External terminals on HV transformer winding. External terminals on LV transformer winding.
  • Page 52 Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- Diag Vector High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio 1φ ⎯...
  • Page 53 Appendix C Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- Diag Vector High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio ⎯...
  • Page 54 Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Diag Vector Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio • 3 •...
  • Page 55 Appendix C Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Diag Vector Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio ⎯...
  • Page 56 Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Diag Vector Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio • • 3 ⎯...
  • Page 57 Appendix C Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Diag Vector Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio •...
  • Page 58 Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Diag Vector Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio • ⎯...
  • Page 59 Appendix C Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999© Megger Winding Connection Winding Tested Winding High- Low- High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Diag Vector Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio •...
  • Page 60 Table C-2 ANSI Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested Winding High- Low- Diag Vector High-Voltage Low-Voltage Phase Shorted Voltage Voltage Measured Group Winding (H) Winding (X) Tested By TTR Winding Winding Turn Ratio • 3 ⎯...
  • Page 61 Appendix C Notes to Table C-3 Transformer terminal markings for power transformers marked in accordance with requirements of International Standard CEI/IEC 76-1:1993. Definition of Symbol Designations 1U, 1V, External terminals on HV transformer winding (alternate notation U, V, W). 2U, 2V, External terminals on LV transformer winding (alternate notation u, v, w).
  • Page 62 Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio 1 φ 1 φ...
  • Page 63 Appendix C Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio ⎯ 1U-1W 2U-2N U1•...
  • Page 64 Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio ⎯ 1U-1V 2U-2N U1•...
  • Page 65 Appendix C Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio 1V-1W 1U-(1V+1W) 2W-2N 1.5U1...
  • Page 66 Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio 1V-1W 1U-(1V+1W) 2N-2W 1.5U1...
  • Page 67 Appendix C Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio ⎯ 1U-1N 2N-2U ⎯...
  • Page 68 Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio 1V-1W 1U-(1V+1W) 2U-2V •...
  • Page 69 Appendix C Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio ⎯ 1U-1V 2U-2N •...
  • Page 70 Table C-3 CEI/IEC 76-1:1993 Transformer Winding Phase Relationship Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio 1V-1W 1U-(1V+1W) 2W-2U •...
  • Page 71 Appendix C Notes to Table C-4 Transformer terminal markings for power transformers marked in accordance with requirements of Australian Standard 2374, Part 4-1982. Definition of Symbol Designations External terminals on HV transformer winding (A External terminals on LV transformer winding (a External neutral terminal on HV transformer winding.
  • Page 72 Table C-4 Transformer Winding Phase Relationship (Australian Std. 2374, Part 4 - 1982) Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio 1 φ...
  • Page 73 Appendix C Table C-4 Transformer Winding Phase Relationship (Australian Std. 2374, Part 4 - 1982) Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding...
  • Page 74 Table C-4 Transformer Winding Phase Relationship (Australian Std. 2374, Part 4 - 1982) Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio YNy0 ⎯...
  • Page 75 Appendix C Table C-4 Transformer Winding Phase Relationship (Australian Std. 2374, Part 4 - 1982) Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding...
  • Page 76 Table C-4 Transformer Winding Phase Relationship (Australian Std. 2374, Part 4 - 1982) Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding Winding Turn Ratio •...
  • Page 77 Appendix C Table C-4 Transformer Winding Phase Relationship (Australian Std. 2374, Part 4 - 1982) Copyright 1999 © Megger Winding Connection Winding Tested High- Low- Diag Vector High-Voltage Low-Voltage Phase External Voltage Voltage Measured Group Winding Winding Tested Jumpers Winding...
  • Page 78 AVTMTTR25 Rev C April 2008...

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