Vanguard ATRT-01_01B_01D - Manual (Page 5)

Model ATRT-01 (v) Operating Instructions
Rev 02
May 02, 2002
4
1.0 Introduction
The Model ATRT-01 is a microprocessor-based, field-portable, automatic, transformer, turns-
ratio test meter designed for on-site measuring of: turns ratios, winding polarity, and no-load
excitation currents of single and 3-phase utility transformers. The ATRT-01 can also test potential
transformers (PTs) and primary current transformers (CTs). The ATRT-01 may not test some
types of donut transformers (i.e., toroidal windings), since its not designed for that application.
2.0 Applicability
The ATRT-01 is available in three models: ATRT-01 (basic), ATRT-01B, and ATRT-01D.
a. The basic ATRT-01 is a line-powered 120/240 V ac (selectable), 50/60Hz unit.
b. The ATRT-01B is powered by a rechargeable lead-acid-gel battery cell. An ATRT-01B
with a fully charged battery will provide a minimum 0f 4 hours of continuous operation. A
built-in charger allows the ATRT-01B’s battery to be recharged while it is testing.
c. The ATRT-01D is powered by 6 D-cell batteries (no ac is used). To conserve battery
power, the ATRT-01D will automatically turn off after sitting idle for 1 minute. A fully
charged set of batteries in the ATRT-01D provides power for up to 200 tests.
3.0 Operating Configuration
The ATRT-01 tests transformer ratio by applying an excitation voltage to primary (H) windings
and monitors secondary (X) winding voltage. The users can also test 3-phase transformers using
the ATRT-01. The user is required to connect the H and X cable leads to the appropriate windings
for each phase. Since the ATRT-01 test lead connections to the (3-phase) transformer bushings are
different for each phase, the ATRT-01 simplifies this procedure by displaying hook-up instructions
on the LCD screen as testing progresses.
The ATRT-01 detects test-lead hook-ups for errors before a test: The ATRT-01 applies a low-
level test voltage (300 mV) across the winding being tested and senses the induced secondary
voltages. Any time an induced voltage is greater than the applied excitation voltage, it's detected as
a hookup error. If a cross-connection error is detected, the ATRT-01 aborts the test and displays:
“Hook-Up Error." But, if no hookup error is detected, the ATRT-01 applies a full 40-volt (20-volt
for ATRT-01B/-01D) test voltage to the transformer being tested and the winding (voltage) ratio is
displayed. Excitation current (in milliamperes) and winding polarity are also displayed.
The ATRT-01 lets users enter nameplate voltages for the specified turns-ratio calculation. From
this calculated turns-ratio, the ATRT-01 will calculate and display the percentage of difference
(based on the difference between the calculated and measured values).
A built-in RS-232C port allows the ATRT-01 to interface with an IBM PC. Transformer-testing
program software, supplied with each ATRT-01, runs on an IBM Windows
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-based computer and
lets users control the ATRT-01 from a computer in the field. With a computer, users can run a test
and save the test results in the field, then recall the test later in an office to generate a test report.
Since data are stored in an ASCII format, test results can be exported into any database desired.