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TRM 25

TRM 25

SCOPE introduces 25 A state of the art precision winding resistance meter, specially designed for field testing as well as factory testing of large transformers up to 500 MVA. Winding resistance value of transformer and rotating machine are directly displayed on 5.7” TFT display. TRM 25 is designed to work in live EHV switchyard conditions, ensuring operator’s safety and repeatability of results. Maintenance time saving is ensured by one time connection to transformer with simultaneous resistance measurement of three / six windings, measurement of resistances of all taps with automated tap change and demagnetization facility. The meter is protected against the back-EMF offered by large inductive windings.



  • Can measure DC winding resistance of large rotating machines, highly inductive test objects like Transformer, Generators and Motors etc.
  • 25A DC current makes it possible to measure low resistances with high accuracy.
  • One time connection to either all windings of primary and / or secondary. Simultaneous measurement reduces connection and measurement time.
  • Change in winding resistance, short or open windings can be detected from measured values.
  • Automatic temperature measurement and temperature corrected value calculation.
  • Measurements of winding resistance of all taps of phases in one go. Recoding, printing and storage of results.
  • OLTC contact opening and compete OLTC performance test facility. Testing of either single or three phases in one test. Single report generation.
  • To know condition of OLTC contacts, OLTC mechanism, transition resistor.
  • Discharges and demagnetizes the object after test.


Parameter TRM 25/ TRM 25+
No of Channels  3/6 Current Channels, 3/6 Volatge Channels , 1 temperature Channel 
Connections One time connection to primary or secondary winding of transformer
Current Ranges  25A, 10A, 5A, 1A, 100mA, 10mA
Resistance Ranges Up to 2000 Ω (Auto ranging)
Resolution  4 ½ digit
Accuracy Value ± 0.5% ± 5 counts
Open Circuit Voltage 50 V 
Demagnetization Facility Yes
Display 5.7” TFT display with touch screen
Printer 58 mm, Inbuilt thermal printer
Communication Port Ethernet for PC communication
Data Port USB for extrernal memory stick connection
External Control Possible via Notebook PC through Ethernet port and software
Temperature measurement Range 0 to 100 deg, Accuracy ± 1 deg, Resolution 0.1deg
Temperature correction For Aluminium & Copper 
Temperature Input Channel Compatible to accept RTD input
User Interface Resistive touch screen
Back EMF Protection Yes. Automatic protection after measurement and during accidental disconnection of current path. Protection operates even if Mains supply fails.
Discharge Facility & Indication Automatic Discharge of DUT & messages on screen
Tap Changer Test Detects discontinuity during tap changer test
OLTC Test Facility(Optional) OLTC test facility with current v/s time graph, Single or Three Phases simultaneously. Available in control through PC option only.
OLTC current Ranges 25A, 10A, 5A
Protection Shut down of power source on Over voltage, Over current,Over temperature
Indications Polarity reversal, Test connection continuity and discharge
Diagnostics Check At power On instrument does self-check of channels and shows the message
Test Leads Measuring leads, AC supply, earth leads and temperature sensor lead
Operating Environment -10°C to 50°C, 95% RH (non condensing)
Storage Temperature -20°C to 60 °C
Heat Run test Yes
Delta connection Measurement  values of each arm of delta winding is calculated and displayed
One side earthing Instrument is able to do the measurement with one side earthing (with Neutral earthing)
Input Supply 110V AC ±15% 50/60 Hz ±10% Or 220V AC ±15% 50/60 Hz ±10%.
Dimensions 630 x 500 x 302mm
Weight 22 Kg. Approx 
Read 12119 times Last modified on Friday, 18 February 2022 12:00
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