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CVT-765 USER’S MANUAL
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1.0 INTRODUCTION
1.1
General Description and Features
The Vanguard CVT-765 is a microprocessor-based, single phase, automatic, transformer turns-
ratio tester. This portable test unit is specifically designed to measure the turns-ratios of
Capacitor Voltage Transformers (CVT’s).
The CVT-765 determines the transformer turns-ratio using the IEEE C57.12.90 measuring
method. It uses a 7500Vac excitation voltage source to accurately measure the turns-ratio of
Capacitor Voltage Transformers with a rating of up to 765KV. The transformer turns-ratio is
determined by precisely measuring the voltages across the unloaded transformer windings.
The CVT-765 can measure the turns-ratios of Capacitor Voltage Transformers ranging from 75
to 15,000. The measured turns-ratio, winding polarity, and winding phase angle are displayed
on the unit’s LCD screen.
A transformer’s nameplate voltages can also be entered, and the CVT-765 will display the turns-
ratio percentage error by comparing the test results with the nameplate voltage values. This
convenient feature eliminates any user-calculation errors when testing transformers.
User Interface
The CVT-765 features a back-lit LCD screen (128 x 64 pixels) that is viewable in bright sunlight
and low-light conditions. A rugged 16-key membrane keypad is used to enter test information
and to operate the unit.
Test Record Storage
The CVT-765 can store 128 records of 33 readings internally, and up to 999 test records on an
external USB Flash drive. Test records can be recalled using the included Transformer Analysis
PC Software.
Computer Interface
A Windows® based (XP/Vista/7) Transformer Analysis Software is provided with each unit and
can be used to remotely control the CVT-765 via the RS-232C port. Using this software, the user
can retrieve test records (from the CVT-765’s memory or a USB Flash drive), analyze test
results, and print test results on a desktop printer. Test results are automatically exported to
PDF, EXCEL, and XML formats.
Operating Voltage
The CVT-765 can be operated from 100-120Vac or 220-240Vac. The proper voltage can be set
using the voltage selection switch on the front panel.
