Vanguard Instruments TRF-250 User manual

TRF-250
THREE-PHASE TRANSFORMER TURNS-RATIO METER
USER’S MANUAL
Vanguard Instruments Company
1520 S. Hellman Ave.
Ontario, California 91761, USA
TEL: [phone]
FAX: [phone]
July 2018
Revision 1

TRF-250 USER’S MANUAL REV 1
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SAFETY SUMMARY
FOLLOW EXACT OPERATING PROCEDURES
Any deviation from procedures described in this User’s Manual may create one or more safety hazards, damage
the TRF-250, damage the test transformer, or cause errors in the test results. Vanguard Instruments Company, Inc.
assumes no liability for unsafe or improper use of the TRF-250. The following safety precautions must be observed
during all phases of test setup, test hookups, testing, and test lead disconnection.
SAFETY WARNINGS AND CAUTIONS
The TRF-250 shall be used only by trained operators. All transformers under test shall be off-line and fully
isolated. Always ground the TRF-250 to a substation ground before connecting the test cables to a transformer. Do
not perform test procedures or service unless another person is also present who is capable of rendering aid and
resuscitation.
SERVICE AND REPAIR
• Do not install substitute parts or perform any unauthorized modification to any TRF-250 test unit.
• Repairs must be performed only by Vanguard Instruments Company factory personnel or by an authorized
repair service provider. Unauthorized modifications can cause safety hazards and will void the manufacturer’s
warranty.
EQUIPMENT RATINGS
IP Rating: The enclosure for TRF-250 has an IP rating of 32.
Pollution Degree: The TRF-250 has a pollution rating of 2.
Operating Voltage: The TRF-250 is rated for use with an operating voltage of 120V or 240V, auto-ranging ±10% of
selected voltage.
Power Cord: The TRF-250 is supplied with a 16 AWG, 16A power cord with a NEMA 5-15P plug. Replacement cable
shall have the same or better rating and is available through the manufacturer.
VENTILATION REQUIREMENTS
The TRF-250 must be operated with the enclosure lid open.
SAFETY SYMBOLS
Indicates that caution should be exercised
Indicates location of chassis ground terminal
CLEANING
To clean the TRF-250:
• Disconnect all cables and turn the unit off.
• Use a soft, lint-free cloth to wipe all surfaces clean.
• Avoid getting moisture in openings and connectors.
• Don't use any cleaning products or compressed air.

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TABLE OF CONTENTS
CONVENTIONS USED IN THIS DOCUMENT ..................................................................................... 1
1.0 INTRODUCTION .................................................................................................................... 2
1.1 General Description and Features ................................................................................... 2
1.2 TRF-250 Technical Specifications ..................................................................................... 4
1.3 Controls and Indicators .................................................................................................... 5
2.0 PRE-TEST SETUP ................................................................................................................... 7
2.1 Operating Voltages .......................................................................................................... 7
2.2 LCD Screen Contrast Control ............................................................................................ 7
2.3 Printer Paper Control ....................................................................................................... 7
2.4 Printer Paper .................................................................................................................... 7
2.5 Replacing the Load Tap Changer Controller Fuses .......................................................... 8
3.0 OPERATING PROCEDURES ................................................................................................... 9
3.1 Connection Diagrams ....................................................................................................... 9
3.1.1. Typical Connections to a Load Tap Changer (LTC) ........................................................... 9
3.1.2. Typical Connections to a Delta-Wye Transformer ......................................................... 10
3.2 Setting the Test Voltage ................................................................................................. 18
3.3 Setting the Date and Time ............................................................................................. 20
3.4 Setting the User Interface Language ............................................................................. 22
3.5 Clearing the List of Trusted Bluetooth Devices .............................................................. 24
3.6 Performing Tests ............................................................................................................ 26
3.6.1. Entering Test Record Header Information ............................................................. 26
3.6.2. Testing a Single Phase Transformer ....................................................................... 29
3.6.3. Testing a Dyn1 (12,000 V/208 V) Transformer ....................................................... 38
3.6.4. Testing a Three Phase Transformer Using Auto Detect Mode .............................. 48
3.7 Working With Test Records ........................................................................................... 55
3.7.1. Saving Test Results to a Test Record ...................................................................... 55
3.7.2. Restoring a Test Record From Flash EEPROM ........................................................ 57
3.7.3. Restoring a Test Record From a USB Flash Drive ................................................... 62
3.7.4. Copying Test Records to a USB Flash Drive ............................................................ 66
3.7.5. Printing or Displaying a Test Record ...................................................................... 69
3.7.6. Printing a Test Record Directory ............................................................................ 71
3.7.7. Erasing Test Records from the Flash EEPROM ....................................................... 74
3.7.8. Erasing Test Records from a USB Flash Drive ......................................................... 78
3.8 Working With Test Plans ................................................................................................ 81
3.8.1. Performing a Test Using a Transformer Test Plan .................................................. 81
3.8.2. Unloading a Test Plan From the Working Memory ................................................ 88
3.8.3. Printing a Test Plan Directory ................................................................................. 89
3.8.4. Printing a Test Plan ................................................................................................. 91
3.8.5. Saving a Test Plan ................................................................................................... 94
3.8.6. Copying a Test Plan to a USB Flash Drive ............................................................... 96
3.8.7. Erasing Test Plans ................................................................................................... 98

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4.0 DIAGNOSTICS, VERIFICATION, AND TROUBLESHOOTING ............................................... 102
4.1 Performing an H and X Cable Diagnostic Test ............................................................. 102
4.2 Performing a Verification Test ..................................................................................... 104
APPENDIX A – TRANSFORMER VECTOR GROUP CODES ............................................................. 106
APPENDIX B – Common ANSI Transformer Descriptions ........................................................... 107
APPENDIX C – CEI/IEC 60076-1 Transformer Descriptions ......................................................... 115
APPENDIX D – Australian Std.2374 Transformer Descriptions ................................................... 122

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LIST OF TABLES
Table 1. TRF-250 Technical Specifications ...................................................................................... 4
Table 2. Functional Descriptions of TRF-250 Controls and Indicators ............................................ 6
Table 3. Descriptions of Single Phase Test Results Elements (Column Format) .......................... 35
Table 4. Descriptions of Single Phase Test Results Elements (Detailed Format) ......................... 37
Table 5. Descriptions of Dyn1 Test Results Elements (Column Format) ...................................... 45
Table 6. Descriptions of Dyn1 Test Results Elements (Detailed Format) ..................................... 47
LIST OF FIGURES
Figure 1. TRF-250 Controls and Indicators ...................................................................................... 5
Figure 2. Typical Connections to a Load Tap Changer (LTC) ........................................................... 9
Figure 3. Typical H & X Cable Connections to a Delta-Wye Transformer ..................................... 10
Figure 4. Typical Connections to a Single Phase Transformer ...................................................... 11
Figure 5. Typical Connections to a Single Phase Auto Transformer ............................................. 11
Figure 6. Typical Connections to a Type A Voltage Regulator ...................................................... 12
Figure 7. Typical Connections to a Type B Voltage Regulator ...................................................... 12
Figure 8. Typical Connections to a Donut Type (un-mounted) Current Transformer (CT) ........... 13
Figure 9. Typical Connections to a Multi-Tap Current Transformer ............................................. 14
Figure 10. Typical Connections to a Bushing Mount CT on a Single Phase Transformer ............. 15
Figure 11. Typical Connections to Bushing Mount CT's on Delta Transformer ............................ 16
Figure 12. Typical Connections to Bushing Mount CT's on Wye Transformer ............................. 17
Figure 13. Single Phase Test Results Printout - Column Format .................................................. 35
Figure 14. Single Phase Test Results Printout - Detailed Format ................................................. 36
Figure 15. Dyn1 Test Results Printout - Column Format .............................................................. 44
Figure 16. Dyn1 Test Results Printout - Detailed Format ............................................................. 46
Figure 17. Typical USB Flash Drive (Thumb Drive) Test Record Directory Printout ..................... 73
Figure 18. Typical Internal Flash EEPROM Test Record Directory Printout .................................. 73
Figure 19. Test Plan Test Results Printout .................................................................................... 87
Figure 20. Sample Printout of a Test Plan from a USB Flash Drive ............................................... 92
Figure 21. Sample Printout of a Test Plan from Internal Memory ............................................... 93

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CONVENTIONS USED IN THIS DOCUMENT
This document uses the following conventions:
• A key, switch, or knob on the TRF-250 is indicated as [KEY], [SWITCH], [KNOB] .
•
Menu names are referenced as “MENU NAME”
• TRF-250 LCD screen output is shown as:
• When instructions are provided, the menu item that should be selected is printed in bold as
shown below (option 3 should be selected):
• Warning messages are indicated as:
WARNING
Warning message
• Important notes are indicated as:
NOTE
Note details
1. OPTION 1
2. OPTION 2
3. OPTION 3
4. OPTION 4
5. OPTION 5
1. OPTION 1
2. OPTION 2
3. OPTION 3
4. OPTION 4
5. OPTION 5

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1.0 INTRODUCTION
1.1 General Description and Features
The TRF-250 is Vanguard's fourth generation transformer turns ratio tester. This latest design
provides a higher turns-ratio test voltage of 250Vac, provides a wireless Bluetooth PC interface,
and features a 44-key "QWERTY"-style membrane keyboard. All these features greatly improve
the accuracy of the turns ratio readings, ease of operation, and reliability.
The TRF-250 determines the turns ratio of the transformer under test using the IEEE C57.12.90
measurement method. The turns-ratio range is from 0.8 to 50,000 to 1. Transformer turns ratio,
excitation current, and winding polarity are displayed on the built-in 128 x 64 pixels graphic LCD
screen. The TRF-250 can be used as a standalone unit or can be computer-controlled.
Auto-Detect Transformer Configuration
The TRF-250 can automatically detect 130 specific vector groups for different transformer types
defined by ANSI, CEI/IEC, and Australian standards.
Transformer Test Voltages
To prevent an accidental wrong test-lead hook-up (e.g., when the operator reverses H and X
leads), the TRF-250 outputs a low-level test voltage to verify the hook-up condition before
applying the full test voltage to the transformer. Four test voltages (4 Vac, 40 Vac, 100 Vac, 250
Vac) allow the TRF-250 to test CT’s and PT’s, as well as power transformers.
Transformer Load Tap Changer Control
Voltage regulator or LTC tap positions can be changed remotely using the unit’s built-in
transformer load tap changer. This feature eliminates the need to manually raise or lower tap
positions from the transformer control panel.
Built-in Thermal Printer
The TRF-250 features a built-in 4.5-inch wide thermal printer that can be used to print test
results.
User Interface
The TRF-250 features a back-lit LCD screen (128 x 64 pixels) that is viewable in both bright
sunlight and low-light levels. The test results screen displays the transformer turns-ratio,
excitation current, phase angle, and percentage error. The unit is controlled via a rugged, 44-
key, "QWERTY"-style membrane keypad.
Computer Interface
In computer-controlled mode, the unit can be controlled via the Bluetooth or USB interface
using the supplied PC software (Transformer Turns-Ratio Analyzer application provided with
each unit). This Windows®-based application can be used to run tests and to store test results
on a PC. Test results can also be exported to Excel, PDF, and XML formats for further analysis.

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Bluetooth PC Interface
The TRF-250 offers an industry-first Bluetooth wireless interface that can be used to remotely
control the unit.
USB Flash Drive Interface
A built-in USB Flash drive interface provides a convenient method for transferring test plans
and test records to or from a USB Flash drive. The user can store up to 999 transformer test
plans and test records on a USB Flash drive, and the supplied PC software can be used to view
the test records.
Internal Test Record Storage
Up to 112 test records can be stored in the TRF-250’s Flash EEPROM memory. Each test record
may contain up to 99 turns-ratio, excitation current, phase angle and nameplate voltage
readings. Test records can be recalled locally or transferred to a PC via the available interfaces
(Bluetooth, USB port, USB Flash drive port).
Transformer Test Plans
The TRF-250 can store up to 128 transformer test-plans in its Flash EEPROM. A test-plan is
comprised of the transformer nameplate voltages for each tap setting. The calculated turns
ratio based on the nameplate voltages is compared with the measured turns-ratio to derive the
percentage error and Pass/Fail results. By using a test plan, a transformer can be quickly tested
and turns-ratio Pass/Fail reports can be reviewed. Test plans can be created with the PC
software and can be transferred to the TRF-250 via the available interfaces (Bluetooth, USB
port, USB Flash drive port).
The 250V Test Voltage Advantage
The 250V test voltage provided by the TRF-250 provides more accurate test results when
measuring the transformer turns ratios of very large transformers with a built-in LTC. The three
figures below show the turns ratio test results and corresponding percentage error of a
600MVA transformer with an LTC in the Lowest position using 40V, 100V, and 250V test
voltages. At the 250V test voltage, the percentage error is less than 0.5% as specified in IEC
60076-1 and IEEE C57.12.00-2006-1 standards.
Test results using 40V test voltage Test results using 100V test voltage Test results using 250V test voltage
%Error > 0.5% %Error > 0.5%
%Error < 0.5%

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1.2 TRF-250 Technical Specifications
Table 1. TRF-250 Technical Specifications
TYPE Portable, lightweight, automatic, 3-phase transformer turns-ratio meter
PHYSICAL SPECIFICATIONS 18”W x 5”H x 12”D(45.7 cm x 12.7 cm x 30.5 cm); Weight: 20 lbs(9.1 Kg)
OPERATING VOLTAGE 100 – 240 Vac, 50/60 Hz
MEASUREMENT METHOD ANSI/IEEE C57.12.90
TURNS-RATIO MEASURING
RANGE 0.8 – 50,000 to 1
TURNS-RATIO ACCURACY 0.8 – 1,999: ±0.1%, 2,000 – 3,999: ±0.25%. 4,000 – 14,999: ±1%,
15,000 – 50,000: ±2% @ 4Vac
0.8 – 1,999: ±0.1%, 2,000 – 3,999: ±0.20%. 4,000 – 14,999: ±1%,
15,000 – 50,000: ±1.5% @ 40Vac
0.8 – 1,999: ±0.1%, 2,000 – 3,999: ±0.20%. 4,000 – 14,999: ±1%,
15,000 – 50,000: ±1.5% @ 100Vac
0.8 – 1,999: ±0.1%, 2,000 – 3,999: ±0.15%. 4,000 – 14,999: ±0.8%,
15,000 – 50,000: ±1.2% @ 250Vac
TEST VOLTAGES 4 Vac @ 1 Amp, 40 Vac @ 200 mA, 100 Vac @ 100 mA, 250 Vac @ 50
mA
EXCITATION CURRENT READING
RANGE 0 – 2 Amperes; Accuracy: ±0.1 mA, ±2% of reading (±1 mA)
PHASE-ANGLE MEASUREMENT 0 – 360 Degrees; Accuracy: ±0.2 degree (±1 digit)
DISPLAY Back-lit LCD screen (128 x 64 pixels) viewable in bright sunlight and low-
light levels
PRINTER Built-in 4.5-inch wide thermal printer
COMPUTER INTERFACES Bluetooth, USB port
EXTERNAL DATA STORAGE One USB Flash drive interface port; Up to 999 transformer test records
can be stored on a USB Flash drive (not included)
INTERNAL TEST RECORD
STORAGE Can store 112 transformer test records internally. Each record holds the test record header and up to 99 readings.
INTERNAL TEST PLAN STORAGE Can store 128 transformer test plans internally. Test plans can be
transferred to the unit from the PC via Bluetooth/USB port or via the USB
Flash drive interface
PC SOFTWARE Windows®-based Transformer Turns Ratio Analyzer application is
included with purchase price
LOAD TAP CHANGER CONTACT 240 Vac, 2 Amps
SAFETY Designed to meet UL 61010A-1 and CAN/CSA C22.2 No. 1010.1-92
standards
ENVIRONMENT Operating: -10˚ to 50˚ C (15˚ to +122˚ F); Storage: -30˚ C to 70˚ C (-22˚
to +158˚ F)
HUMIDITY (MAX) 90% RH @ 40˚ C (104˚ F) non-condensing
ALTITUDE (MAX) 2000m (6562 ft) to fully safety specifications
CABLES One 15-foot single-phase set, one 15-foot 3-phase set, one 25-foot
extension set, one safety ground, one USB, cable bag
WARRANTY One year on parts and labor
NOTE
The above specifications are valid at nominal operating voltage and at a
temperature of 25°C (77°F). Specifications may change without prior notice.

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1.3 Controls and Indicators
The TRF-250 controls and indicators are shown in Figure 1. A leader line with an index number
points to each control and indicator, which is cross-referenced to a functional description in the
corresponding table. The purpose of the controls and indicators may seem obvious, but users
should familiarize themselves with them before using the TRF-250. Accidental misuse of the
controls will usually cause no serious harm. Users should also familiarize themselves with the
safety summary information found on the front page of this User’s Manual.
Figure 1. TRF-250 Controls and Indicators

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Table 2. Functional Descriptions of TRF-250 Controls and Indicators
Item
Number Panel Markings Functional Description
1
EMERGENCY
TURN OFF
“PUSH”
Emergency turn-off test voltage switch.
2 Back-lit LCD screen (128 x 64 pixels), viewable in bright sunlight and
low-light levels.
3 H H voltage connector.
4 3A SLOW BLOW Load Tap Changer controller fuses
5 X X voltage connector.
6 LTC
CONTROL
Load Tap Changer controller connector.
7 4.5-inch wide thermal printer (optional)
8 120/240 Vac, 4A, 50-60Hz
Fuse: F5A 250V
Input power connector and fused power switch with third-wire safety
ground.
9 GROUND Ground stud for connecting to sub-station ground.
10 Rugged "QWERTY" style membrane keypad
11 LTC
CONTROL
Load Tap Changer control buttons.
12
TEST
IN
PROGRESS
This LED flashes in response to commands or when a test voltage is
applied to the test transformer.
13 USB
PC
USB PC interface connector.
14 USB
MEM
USB Flash drive interface port.
15 BLUETOOTH Bluetooth status indicator.

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2.0 PRE-TEST SETUP
2.1 Operating Voltages
The TRF-250 can be powered by ac line voltage of 100-240 Vac, 50/60 Hz.
2.2 LCD Screen Contrast Control
To increase the LCD screen contrast, press and hold the [] key for two seconds. Release the
button when the desired contrast level has been reached.
To decrease the LCD screen contrast, press and hold the [] key for two seconds. Release the
button when the desired contrast level has been reached.
2.3 Printer Paper Control
To advance the thermal printer paper, press and release the [] key.
To retract the thermal printer paper, press and release the [] key.
2.4 Printer Paper
The TRF-250's optional built-in thermal printers use 4.5-inch wide thermal paper for printing
test results. To maintain the highest print quality and to avoid paper jams, the use of thermal
paper supplied by Vanguard Instruments Company is highly recommended. Additional paper
can be ordered from the following sources:
Vanguard Instruments Co, Inc.
1520 S. Hellman Avenue
Ontario, CA 91761
Tel: [phone]
Fax: [phone]
Part Number: VIC TP-4 paper
BG Instrument Co.
13607 E. Trent Avenue
Spokane, WA 99216
Tel: [phone]
Fax: [phone]
Part Number: VIC TP-4 paper

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2.5 Replacing the Load Tap Changer Controller Fuses
The TRF-250 features a built-in Load Tap Changer (LTC) controller that can raise or lower the
LTC tap position from the front panel. The LTC controller circuit uses two 250 Vac/2A, NO, relay
contacts to simulate the LTC Raise/Lower switches. Each relay contact is protected by a 1A/250
Vac fuse (5 X 20mm, fast acting). The fuse should be replaced with a Littlefuse P/N 217001 or
equivalent.

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3.0 OPERATING PROCEDURES
The TRF-250 should always be grounded with the provided ground cable before connecting H
and X cables. The transformer bushings should also be grounded before connecting test leads
to the transformer. This will prevent inducing any voltages into the TRF-250. All transformer bus
connections must be removed, and the transformer must be isolated before performing any
tests. Typical transformer connection diagrams are illustrated in the sections below.
3.1 Connection Diagrams
3.1.1. Typical Connections to a Load Tap Changer (LTC)
Figure 2. Typical Connections to a Load Tap Changer (LTC)

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3.1.2. Typical Connections to a Delta-Wye Transformer
Figure 3. Typical H & X Cable Connections to a Delta-Wye Transformer

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3.1.3. Typical Connections to a Single Phase Transformer
Figure 4. Typical Connections to a Single Phase Transformer
Figure 5. Typical Connections to a Single Phase Auto Transformer

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3.1.4. Typical Connections to a Voltage Regulator
Figure 6. Typical Connections to a Type A Voltage Regulator
Figure 7. Typical Connections to a Type B Voltage Regulator

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3.1.5. Typical Connections to a Donut Type (un-mounted) Current Transformer
Figure 8. Typical Connections to a Donut Type (un-mounted) Current Transformer (CT)
NOTE
The H and X test leads are reversed for the CT ratio test connections shown
above.

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3.1.6. Typical Connections to a Multi-Tap Current Transformer
Figure 9. Typical Connections to a Multi-Tap Current Transformer

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3.1.7. Typical Connections to a Bushing Mount CT on a Single Phase Transformer
Figure 10. Typical Connections to a Bushing Mount CT on a Single Phase Transformer