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Model 3CTR - Three Phase AC RMS Current Transducer

The 3CTR series current transducers are designed to measure AC current in 1 phase and 3 phase systems. They convert the AC current signal to an isolated DC output that is directly proportional to the input rms current. The 3CTR models are RMS calibrated current transducers, with 4-20mA (4mA live zero) or voltage (0-10V) outputs. Auxiliary power is required to ensure that 4mA output signal is present when the input is zero. Because the 3CTR is true RMS sensing RMS calibrated, it allows measurement of distorted waveforms of up to 9th harmonic with a crest factor of 5. The 3CTR is typically used in current measurement where distorted current waveform are common, such as pumps, motor controllers, UPS and thyristor drives. The above units are also used to measure current in energy management systems, switchboards, generator and telemetery controls. Isolation of 2.5kV is provided between the input and output signal, allowing the output to be fed to PLC computer systems and even conventional analogue meters.


  • Accurate measurement of the true RMS value of input current over a wide frequency range
  • Input/output dielectric test 2500V
  • 0.25% Accuracy


  • For use in applications where measurement of non-sinusoidal waveforms is required
  • Designed for use on three-phase systems, but may also be used to monitor three single-phase circuits where panel space is a premium
  • Designed to withstand motor start-up transients


Connection Diagram

Case Dimensions

If you have any queries regarding the 3CTR or require specifications outside our standard ranges please do not hesitate to contact us..

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