Megger TTR20 User manual

AVTMTTR20
Rev. 4
Dec 2015
Instruction Manual AVTMTTR20
for
TTR20 Handheld TTR
Transformer Turn Ratio Test Set
Catalog Nos. TTR20 and TTR20-1
(TTR20 DISCONTINUED)
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

TTR20 and TTR20-1 Handheld TTR
Transformer Turn Ratio Test Set
Instruction Manual

Copyright Notice
Copyright 2015 by Megger. All rights reserved.
Disclaimer Notice
The information contained in this manual is believed to be adequate for the
intended use of the product. 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.
WARRANTY
Products supplied by Megger are warranted against defects in material and
workmanship for a period of one year following shipment. Our liability is
specifically limited to replacing or repairing, at our option, defective equipment.
Equipment returned to the factory must be shipped prepaid and insured. This
warranty does not include batteries, lamps, or other expendable items, where the
original manufacturer's warranty shall apply. We make no other warranty. The
warranty is void in the event of abuse (failure to follow recommended operating
procedures) or failure by the customer to perform specific maintenance as
indicated in this manual.

AVTMTTR20 Rev 4 Dec 2015 i
TABLE OF CONTENTS
1INTRODUCTION ......................................................................................................................... 1
About the TTR20 (TTR20-1) ...................................................................................... 1
Electrical Theory and Practice ................................................................................... 2
Applications for the TTR20 ........................................................................................ 4
Upon Receipt of the TTR20 ....................................................................................... 5
Safety First................................................................................................................. 5
How to Use This Manual............................................................................................ 5
2SAFETY ................................................................................................................................... 7
Overview.................................................................................................................... 7
Safety Requirements ................................................................................................. 7
Cautions and Warnings.............................................................................................. 8
3CONTROLS &CONNECTORS.............................................................................................. 9
Overview.................................................................................................................... 9
Connectors .............................................................................................................. 10
Connectors .............................................................................................................. 10
4SETUP,CONNECTIONS AND OPERATION .................................................................................. 11
General Instructions................................................................................................. 11
Transformers ........................................................................................................... 11
Single-Phase, Two-Winding Transformers .............................................................. 12
Distribution Transformers with Two Secondary Windings........................................ 12
Three-Phase, Two-Winding Transformers ............................................................... 16
Three-Phase, Three-Winding Transformers ............................................................ 16
Current Transformers (CTs)..................................................................................... 16
General Operating Procedure.................................................................................. 20
Description of Menus and Test Screens .................................................................. 20
Use with the Optional Printer ................................................................................... 23
HyperTerminal Configuration ................................................................................... 25
5MAINTENANCE AND TROUBLESHOOTING.................................................................................... 27
Maintenance ............................................................................................................ 27
Calibration Check..................................................................................................... 27

AVTMTTR20 Rev 4 Dec 2015
ii
TTR20 Functional Test ............................................................................................ 28
Battery Replacement ............................................................................................... 29
Troubleshooting ....................................................................................................... 30
Error Messages........................................................................................................ 31
Repair ...................................................................................................................... 33
APPENDIX A-SPECIFICATIONS................................................................................................... 35
Electrical .................................................................................................................. 35
Environmental Conditions ........................................................................................ 37
Physical Data........................................................................................................... 37
APPENDIX B-ORDERING INFORMATION &SPARE PARTS LIST ...................................................... 39
APPENDIX C-CONNECTIONS AND VECTOR VOLTAGE DIAGRAMS ................................................... 41

AVTMTTR20 Rev 4 Dec 2015 iii
LIST OF ILLUSTRATIONS
Figure 1-1. TTR20 Single-Phase Test Set Block Diagram ..................................................... 4
Figure 3-1 TTR20 Display & Control Panel ........................................................................... 9
Figure 3-2 TTR20 Top Side Connector Panel ..................................................................... 10
Figure 4-1 Setup for Testing Single-Phase Transformer ..................................................... 13
Figure 4-2 Setup for Testing Single-Phase Autotransformer............................................... 13
Figure 4-3 Setup for Testing Single-Phase, Type A Step Voltage Regulator ...................... 14
Figure 4-4 Setup for Testing Single-Phase, Type B Step Voltage Regulator ...................... 14
Figure 4-5 Setup for Testing X1 – X2 Winding of Distribution Transformer......................... 15
Figure 4-6 Setup for Testing X3 – X2 Winding of Distribution Transformer......................... 15
Figure 4-7 Setup for Testing X1 – X3 Winding of Distribution Transformer......................... 15
Figure 4-8 Setup for Testing Unmounted Current Transformer ........................................... 18
Figure 4-9 Setup for Testing Taps on Multiple Tap CT........................................................ 18
Figure 4-10 Setup for Testing BCT Mounted on Single-Phase Two-Winding Transformer ... 19
Figure 4-11 TTR20 Opening Display Screen......................................................................... 20
Figure 4-12 Start Test Screen ............................................................................................... 21
Figure 4-13 Test in Progress Screen..................................................................................... 22
Figure 4-14 TTR20 Test Result Screen................................................................................. 22
Figure 4-15 Sample Test Report ........................................................................................... 23
Figure 4-16 Printer Configuration Printout............................................................................. 24
LIST OF TABLES
Table 5-1 Troubleshooting Guide ........................................................................................ 30
Table 5-2 Self-test Error Messages ..................................................................................... 31
Table 5-3 Test Error Messages ........................................................................................... 31
Table 5-4 Miscellaneous Message ...................................................................................... 32
Table C-1 ANSI Transformer Winding Phase Relationship ................................................. 42
Table C-2. ANSI Transformer Winding Phase Relationship................................................. 44

AVTMTTR20 Rev 4 Dec 2015 1
1
INTRODUCTION
About the TTR20 (TTR20-1)
The TTR20 and TTR20-1 Handheld TTR®Test Sets are fully automatic, self-
checking, self-calibrating units. The TTR20-1 has metal lead connections versus
plastic for the TTR20 (Replaced with the TTR20-1). This manual still refers to the
TTR20 as a general model number, but for purposes of new instruments, only
the TTR20-1 is currently sold.
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. The TTR20 Handheld TTR®
Test Set is powered by six AA-size replaceable alkaline batteries.
The test set can be used to test single-phase and three-phase transformers, both
with and without taps in accordance with the requirements of the IEEE C57.12.90
– 2013 standards. For three-phase transformers, the test set is connected to
each of the three phases of the transformer to be tested, and measurements are
made on a phase by phase basis.
Turn ratio, phase displacement (polarity), and excitation current are displayed on
a large LCD. Transformer excitation current helps to detect transformer shorted
turns or an unequal number of turns connected in parallel. Operating condition
(error) messages identify incorrect test connections, abnormal operating
condition, or winding problems. Test results can be printed out on an optional
printer.
Features include:
Fully automatic operation.
Self-checking at power-up.
Self-calibration at each measurement.
User-friendly, one button operation.
Test turn ratio, excitation current, and phase displacement (polarity).
Easy measuring of single and three phase (phase by phase) transformers, as
well as potential & current transformers.
Checking reverse test lead or winding connections at start of each test.

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AVTMTTR20 Rev 4 Dec 2015
2
External optional printer records test data.
Three automatically selected excitation test voltages: 8 V, 1.5 V, and 0.5 V.
Testing to ANSI standards.
Leads marked to ANSI standards.
Large, easy-to-read LCD shows alphanumeric data
Meets the requirements of both the European EMC and Low Voltage Directives
(CE mark).
Trouble-free operation in switchyards under electrostatic and magnetic
interference conditions.
Electrical Theory and Practice
How the TTR20 Works
The TTR20 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.
Transformer Turns Ratio
Transformer Turns Ratio is the ratio of the number of turns in the high voltage
winding to that in the low voltage winding. Transformer ratio can change due to
several factors, including physical damage from faults, deteriorated insulation,
contamination and shipping damage.
A Transformer Turns Ratio Test Set such as the TTR20 can directly measure the
turns ratio of single-phase transformers as well as three-phase transformers.
Deviations in these measurements will quickly indicate problems in transformer
windings and in the magnetic core circuits. If a transformer ratio deviates more
than 0.5 percent from the rated voltage ratio, it may not operate reliably. To
measure small ratio changes such as this, the accuracy of a Megger TTR20 is
needed.
Excitation Current
The TTR20 is capable of measuring exciting current by applying voltage to one of
the transformer’s windings. An accurate measurement of exciting current can
provide information about the condition of a transformer’s core. Unwanted
circulating currents, unintentional grounds or even an incipient short circuit can
affect the exciting current and indicate a problem.
Transformer Polarity
Polarity of a distribution transformer becomes of interest in order to determine its
proper connection within a power network. The Megger TTR20 will identify
normal (in phase) and reverse polarity of the single-phase transformers.