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Model R120 version 2.0

Transformer Turn Ratio Meter
High Accuracy - Three Phase

  • Power Transformers
  • Distribution Transformers
  • Instrument Transformers - Voltage and Current


  • Rotary phase selector switch makes tests easier and faster, this is appreciated when testing big transformers
  • Polarity inverter facilitates tests of transformers of any connection group
  • Constant sensitivity upon the whole ratio range
  • Digital display of transformer nominal ratio
  • High reliability because of its accurate inductive voltage divider - This provides long term stability avoiding frequent calibrations
  • Ratios up to 1000 can be measured without auxiliary transformer
  • Measures percentage deviation, phase angle deviation, excitation current.
  • Great accuracy is achieved also when testing big transformers


The Conimed TTR Meter Model R120 2.0 can be used with great advantage for field testing or in the shop.

It has been proved that greatest accuracy is achieved when test voltage applied to high voltage windings of power transformers is above 100 V. This is very significant when the transformer under test has high short circuit impedance. The test voltage of Model R120 is 120 V.

An optional transformer duplicates test voltage for testing PTs when turn ratio is between 1000 and 2000 and supplies 12 V for testing CTs.

Model R120 is essentially an Inductive Voltage Divider which ratio can be adjusted between 1 and 1000, a phase measurement circuit and an electronic tuned null detector. Two rotary switches allow the operator to select the phases to be measured. Transformers of any connection group can be easily tested without the need of changing the connections.

Long testing cables are supplied for testing any type of transformers.


Ratio Range: 1 - 1000
Test voltage: 120 V applied to high voltage winding of transformer under test
Excitation current range: 0 - 100 mA

Range: 0,5 % - Accuracy 0,1 %

Range: 1 cr - Accuracy 0,2 cr

R120 A: 220 V - 50 Hz
R120 B: 110 V - 60 Hz
Optional: 12 VCC with external converter

Portable attache 52 x 35 x 27 cm - 15 kg

High voltage: Three phases + neutral, 10 m long
Low voltage: Three phases + neutral, 7 m long

Optional Accessory:
Transformer 120 / 240 - 12 V
Output 240 V: extends ratio range up to 2000
Output 12 V: for testing CTs with ratio up to 100


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