
WRM-10
lightweight winding resistance meter
ightweight winding resistance mete
Vanguard Instruments Company, Inc.
www.vanguard-instruments.com

WRM-10
lightweight winding resistance meter
The WRM-10 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-10 provides stable resistance readings of very
large transformers by utilizing a 36Vdc power supply capable of outputting up to 10 Amperes. The resistance reading of a 100MVA transformer
can be achieved in 5 minutes or less. The unit’s power supply is cooled by
heavy-duty fans designed for continuous operation.
outstanding features
• Auto discharge circuit for operator safety
• Auto current ranging from 10 mA to 10 A
• Digital resistance reading from 1 micro-ohm to
2,000 ohms
• Lightweight (27 lbs / 12.2 kg)
WRM-10 connections
Since the WRM-10 can accurately measure resistances ranging from 1 microohm to 2,000 ohms, it can also be used
to measure EHV circuit-breaker contact
resistance, motor winding resistance, or
any low resistance. In addition to measuring the resistance value, the WRM-10
also checks the “make-before-break”
tapswitching sequences of voltage regulators and load tap changers.
The WRM-10 is furnished with three 50foot 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-10 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.
User Interface
The WRM-10 features a back-lit LCD screen (16
characters by 2 lines) that is viewable in both
bright sunlight and low-light levels. A “turn-andpush” knob is used to control the unit. A built-in
RS-232C interface port is provided for diagnostic testing and fi rmware upgrades.
2

WRM-10 Controls & Indicators
Resistance Input
Channel #1
Warning Indicators
Current Output
Connectors
Resistance Input
Channel #2
WRM-10 specifi cations
type portable transformer winding resistance meter
physical specifi cations 17”W x 12K”H x 10K”D, (42.6 cm x 32.0 cm x 27.0 cm); Weight: 27 lbs (12.2 kg)
input power 100 ¬ 120 Vac or 200 ¬ 240 Vac (factory pre-set), 50/60 Hz
resistance reading range 1 micro-ohm ¬ 2,000 ohms
accuracy 1 ¬ 19,999 micro-ohms: ±0.5% reading, ±1 count;
20 ¬ 999 milli-ohms: ±1% reading, ±1 count;
1 ¬ 2,000 ohms: ±1.5% reading, ±1 count
test voltage 36 Vdc max
test current range auto range, 10 Amperes max
display back-lit LCD Screen (16 characters by 2 lines); viewable in bright sunlight and low-light levels
control Single “turn-and-push” knob
computer interface RS-232C port used for factory calibration and diagnostics
safety designed to meet IEC61010 (1995), UL61010A-1, CSA-C22.2 standards
environment Operating: -10°C to +50°C (+15°F to +122°F); Storage: -30°C to +70°C (-22°F to +158°F)
humidity 90% RH @ 40°C (104°F) non-condensing
altitude 2,000 m (6,562 ft) to full safety specifi cations
cables three 50-foot test cables, ground cable, power cord and cable bag
options transportation case
warranty one year on parts and labor
NOTE : the above specifi cations are valid at nominal voltage and ambient temperature of +25°C (+77°F). Specifi cations are subject to change without notice.
Power Switch
Back-lit LCD Screen
(16 characters by 2 lines)
RS-232C Interface
(for factory diagnostics and calibration)
Function Control Knob
ordering information
Part number WRM-10 WRM-10 and cables
Part number WRM-10 CASE WRM-10 shipping case
Part number WRM-10 50-FT CABLES 50-foot test cables
33

Instruments designed and developed
by the hearts and minds of utility
electricians around the world
Vanguard Instruments Company, (VIC), was founded in 1991.
Currently, our 28,000 square-foot facility houses Administration,
Design & Engineering, and Manufacturing operations. From its
inception, VIC’s vision was, and is to develop and manufacture
innovative test equipment for use in testing substation EHV circuit
breakers and other electrical apparatus.
The fi rst VIC product was a computerized circuitbreaker analyzer,
which was a resounding success. It became the forerunner of an entire
series of circuitbreaker test equipment. Since its beginning, VIC’s
product line has expanded to include microcomputer-based, precision
micro-ohmmeters, single and three phase transformer winding turnsratio testers, transformer winding-resistance meters, mega-ohm
resistance meters, and a variety of other electrical utility maintenance
support products.
VIC’s performance-oriented products are well suited for the utility
industry. They are rugged, reliable, accurate, user friendly, and
most are computer controlled. Computer control, with innovative
programming, provides many automated testing functions. VIC’s
instruments eliminate tedious and time-consuming operations, while
providing fast, complex, test-result calculations. Errors are reduced
and the need to memorize long sequences of procedural steps is
eliminated. Every VIC instrument is competitively priced and is
covered by a liberal warranty.
Vanguard Instruments Company, Inc.
1520 S. Hellman Avenue • Ontario, California 91761, USA
Phone 909-923-9390 • Fax 909-923-9391
www.vanguard-instruments.com
August, 2012