Atec WRM-40 User Manual

WRM-40

winding resistance meterwinding resistance meter

Vanguard Instruments Company, Inc.

www.vanguard-instruments.com

WRM-40

winding resistance meter

The WRM-40 is designed to accurately measure the winding resistance of
highly inductive power transformers. The unit’s dual resistance-reading input
channels can measure two winding resistances simultaneously, and four-wire
(Kelvin) connections provide high accuracy and require no lead compensation.
The WRM-40 provides stable resistance readings of very large transformers
by utilizing a 36Vdc power supply capable of outputting up to 40 Amperes.
The resistance reading of a 500MVA transformer can be achieved in 5 minutes
or less. The unit’s power supply is cooled by four heavy-duty fans designed for
continuous operation. For greater fl exibility in the fi eld, the WRM-40 comes
with a built-in 2.5-inch wide thermal printer used for printing test reports.

Since the WRM-40 can accurately measure re­sistances ranging from 1 microohm to 500 ohms,
it can also be used to measure EHV circuit­breaker contact resistance, motor winding resis­tance, or any low resistance. If the transformer
winding temperature is entered, the WRM-40
can calculate the equivalent resistance value of
the winding material (aluminum or copper) at
any standard reference temperature. Also, a spe­cial test mode can run a test for up to 45 minutes
while saving resistance readings at one-minute
intervals. In addition to measuring the resistance
value, the WRM-40 also checks the “make-be­fore-break” tap switching sequences of voltage
regulators and load tap changers.

The WRM-40 can store test results in Flash EE­PROM. Test results can be printed on the built-in

2.5-inch wide thermal printer or can be trans­ferred to a PC via the RS-232C interface port.

The WRM-40 is furnished with three 50-foot
test cables. Each test cable lead is terminated
with a quick-disconnect test clip.

Built-in Safety Features

At the end of each test, the WRM-40 automati­cally dissipates the stored energy in the trans­former. This discharge circuit will continue to
work even if the supply voltage is lost. For added
safety, the unit’s power supply is thermally pro­tected from over-load damage.

Internal Test Record
Storage

The WRM-40 can store 63 test records (up to
48 readings per test record) in Flash EEPROM.
Test records can be retrieved and printed on the
built-in thermal printer or can be transferred to a
PC via the RS-232C interface port. A Windows®

-based application is provided with each WRM­40 that can be used to retrieve test records from
the WRM-40 and can also be used to export re­cords in Microsoft® Excel format.

User Interface

The WRM-40 features a back-lit LCD screen (20
characters by 4 lines) that is viewable in both
bright sunlight and low-light levels. A rugged,
alpha-numeric, membrane keypad is used to
control the unit.

Built-in Thermal Printer

The WRM-40 features a built-in 2.5" wide ther­mal printer that can be used to print test reports
in the fi eld.

outstanding features

• Auto discharge circuit for operator safety

• Auto current ranging from 10 mA to 40 A

• Digital resistance reading from 1 micro­ohm to 500 ohms

• Stores 63 records (of 48 readings each)

• Built-in 2.5-inch wide thermal printer

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