Atec 550503 User Manual

Three-Phase TTR

®

Transformer Turns Ratio Test Set

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Fully automatic operation

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Measures three phases simultaneously

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Highest ratio measurement (20,000:1);
highest accuracy (0.1%)

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Built-in storage and downloading
capabilities

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Measures ALL power transformers,
PTs and CTs

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Displays % error vs. name plate and
pass/fail limits

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Operator choice of “quick” test or
complete “full” test

Three-Phase TTR

®

Transformer Turns Ratio Test Set

DESCRIPTION

The Three-Phase Automatic TTR is designed to measure
the turns ratio of power, instrument, and distribution
transformers in a substation or manufacturing environment.
At 16.5 lbs (7.5 kg), it weighs less than any other
commercially available instrument. A rugged and robust
design makes this TTR well suited for use in a variety of
harsh environments. The TTR is also particularly suited for
testing in power transformer manufacturing environments
where testing of complex, three-phase substation power
transformers can be performed quickly while minimizing
the possibility of errors.

This new TTR measures the highest turns ratio range in the
industry (10,000:1) and also provides the highest accuracy
(0.1%). No other instrument’s performance is comparable
that is commercially available today.

Another excellent feature of this new TTR is the ability to
measure phase deviation (in minutes or centiradians) of
the transformer primary versus secondary. This will
quickly indicate problems in a transformer such as partial
shorted turns and core faults. This measurement is also
useful in verifying phase errors of all types of PTs and CTs.

The TTR also features special software capabilities. The
TTR comes equipped with sufficient onboard memory to
store up to 200 test results in the field for later retrieval in
the office. Test results can be printed on an optional serial
printer whenever a hard copy is desired, or the data can be
downloaded to a PC. Identification of individual test
readings is also easily done. The system software allows
entry of the transformer alphanumeric serial number,

transformer type and tap information for each test
performed.

This new TTR also comes with a unique optional, remote
control software program. This Windows

®

based program
permits control and operation from a PC keyboard,
download of test data from the TTR to a PC, print out a
test results report and assist in the preparation of management
and/or analysis reports using either Excel

®

or Access®.

Realizing the extreme environments in which the TTR must
operate, special attention has been paid to making it extra
rugged (with a hard, shock resistant case), yet incredibly
light weight (16.5 lbs). It features a high contrast LCD
screen which can be seen in bright or ambient light and
comes equipped with specially designed leads which
provide the necessary flexibility needed in cold weather
conditions.

APPLICATIONS

The proper operation of a transformer relies almost
entirely on the electrical properties of its windings. To
ensure continued proper operation, transformers are tested
to verify that their electrical properties have not changed
from design specifications.

A TTR is an extremely useful instrument for testing
transformer windings, because it can locate several types
of problems within a transformer. It is also ideal to use for
testing in Meter shops for the upcoming inspection of CTs
and PTs. It can determine the no load accuracy of all CTs
and PTs and also determine the need to fur ther test faulty
CTs and PTs.

Three-Phase TTR

®

Transformer Turns Ratio Test Set

The new TTR applies voltage to the high voltage winding
of a transformer and accurately measures the resulting
voltage from the low voltage winding. In addition to turns
ratio, the unit measures excitation current, phase angle
deviation between the high and low voltage windings and
percent ratio error.

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. A Transformer Turns Ratio Test Set such as the
Three-phase Automatic TTR can directly measure the ratio
of most types of transformers. Transfor mer ratio can
change due to several factors, including physical damage
from faults, deteriorated insulation, contamination and
shipping damage. If a transformer ratio changes 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 Biddle TTR is needed.

Exciting Current

The exciting current is the current that maintains the
magnetic flux excitation in the core of a transformer.

A Transformer Turns Ratio Test Set such as the
Three-phase Automatic TTR is capable of measuring
exciting current because they apply voltage to one of the
transformers windings. An accurate measurement of
exciting current can provide information about the
condition of a transformer’s core. Unwanted circulating
currents or unintentional grounds can affect the exciting
current and indicate a problem.

Phase Angle Deviation

The phase angle deviation is the relationship between the
voltage signal applied to the high voltage winding and the
voltage signal extracted from the low voltage winding.

The phase deviation between the high and low side of a
transformer is generally very small. If there is deterioration
or damage in the transformer core, however, the phase
deviation can change significantly. The Three-phase T TR
can measure this phase relationship with the resolution
necessary to detect a problem.

More information about a transformer’s electrical proper ties
can be found in the IEEE Standard Test Code for
Transformers, C57.12.90, or by contacting Megger.

FEATURES AND BENEFITS

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Measures the widest turns ratio range in the industry
(10,000:1) and also provides the highest accuracy (0.1%).

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Enables the operator to enter the ratio of the transformer
and all of it’s taps. This allows the operator to know
immediately when a tap is outside the acceptable limits.
Also allows for a pass/fail limit so problem taps can be
easily flagged.

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Comes equipped with “remote-control” switch for single
person testing. This allows the operator to test
transformers with “LTCs” very quickly.

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Records ratio errors for bushing CTs to an accuracy of
±0.1% nameplate. This reduces the need for additional
test equipment and improves set-up time.

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Measures the phase deviation (in minutes) of the
transformer primary versus secondary. This quickly
indicates problems in the transformer such as partial
shorted turns and core faults. This measurement is also
useful in verifying phase errors in all types of PTs and
CTs.

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Perfect for meter shops, the TTR can be used for
inspection purposes by using it to determine the no-load
accuracy of most CTs and PTs. Also, it can be used to
determine the need to further test potentially faulty CTs
and PTs.

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This instrument is also ideal for use by power
transformer manufacturers. Its unique testing
procedures and storage capability allows an operator to
set up and test difficult three-phase transformers (with
multiple tap changers and bushing CTs) in a quarter of
the time than it used to take with the former Biddle
TTR. This test also includes a pass/fail limit of
individual ratios.

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A “Quick Test” Mode provides a fast determination of
the turns ratio for single and three-phase transformers,
thus saving time.

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Displays all values for each test including measured and
calculated ratio, exciting current, ratio error, and phase
angle deviation, thus providing comprehensive and
conclusive data.

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Automatic self-calibration for each test.

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Rugged, lightweight design ideally suited for a harsh
field and substation environment.

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Three user selectable standards: ANSI, IEC, and
Australian. Also meets IEC 1010 as well as other safety
standards such as CSA and UL.

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Six user selectable languages: French, German, Italian,
Portuguese, Spanish and English.

Example of the TTR LCD screen which shows test data
from a three-phase transformer test.

THREE PHASE TRANSFORMER TEST

TEST: 105 ID: A13579CV0246 DIAG: 31 Yzn11

TAPS TESTED: 3 - 16 R
H VOLTAGE: 25000 X VOLTAGE: 5000
CALCULATED TURNS RATIO: 5.000
TEST VOLTAGE: 80 V

ABC

RATIO 5.102 5.015 4.986
% DEVIATION 2.04 0.30 -0.28
PHASE (min.) 1.2 2.4 1.8
lexc (mA) 20.6 10.5 7.78

SELECT: 1 - PRINT 2 - STORE 3 - NEXT TEST

4 - PRINT TEST 5 - MAIN MENU