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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