Vanguard ATRT-03_03B - Manual (Page 8)

REV 7 ATRT-03, ATRT-03A, AND ATRT-03B USER’S MANUAL
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1.0 INTRODUCTION
1.1 General Description and Features
The ATRT-03 line is Vanguard’s second generation family of microprocessor-based, automatic,
three phase, transformer turns-ratio testers. The ATRT-03 line consists of the following three
models:
• The ATRT-03 is a line-powered, 120/240 Vac (selectable), 50/60 Hz turns-ratio tester
featuring a built-in thermal printer.
• The ATRT-03A can be powered either by an internal rechargeable lead acid battery, by
90-240 Vac, by 110-240 Vdc, or by a 12 Vdc external source. The internal battery
provides 3 hours of operational time. The ATRT-03A also features a built-in thermal
printer.
• The ATRT-03B is a line-powered, 120/240 Vac (selectable), 50/60 Hz turns-ratio tester
without a built-in thermal printer.
The general term “ATRT-03” or “ATRT” is used in this manual to refer to any of the ATRT-03
models. Any differences are clearly described where applicable.
The ATRT-03 determines the transformer turns-ratio using the IEEE C57.12.90 measurement
method. The transformer turns-ratio (ranging from 0.8 to 15,000) is determined by precisely
measuring the voltages across the unloaded transformer windings. To ensure accuracy, the
ATRT-03’s measuring circuitry self-calibrates before each measurement. It requires neither
adjustment nor temperature compensation. The ATRT-03’s turns-ratio measurement accuracy
is 0.1% or better.
The ATRT-03 can perform a specific test for each transformer type (such as single phase, delta
to Y, Y to delta, delta to delta, or Y to Y) without the need to switch test hookup cables. Also,
the unit’s automatic transformer phase detection feature can detect different transformer
vector diagrams. The ATRT-03 can automatically detect and test 67 transformer types defined
by ANSI, CEI/IEC and Australian standards.
Transformer Test Voltage
To prevent an accidental wrong test-lead hook-up (e.g., when the operator reverses H and X
leads), the ATRT-03 outputs a low-level test voltage to verify the hook-up condition before
applying the full test voltage to the transformer. Three test voltages (8 Vac, 40 Vac, 100 Vac)
allow the ATRT-03 to test CT’s and PT’s, as well as power transformers.
User Interface
The ATRT-03 features a back-lit LCD screen (20 characters by 4 lines) that is viewable in both
bright sunlight and low-light levels. The test results screen displays the transformer turns-ratio,
excitation current, and turns-ratio accuracy. The unit is controlled via a rugged, 16-key,
membrane keypad.