LFR Current Probe


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The LFR is ideal for power quality applications. It has a small, predictable phase error, for power measurements at 45/65Hz. The wide bandwidth allows accurate measurement up to and even above the 400th harmonic.

The LFR is very linear with current magnitude and the 10:1 switch selectable current range enables measurement over a wide dynamic range.

Standards and Approvals

  • CE marked
  • Complies with IEC61010-1
  • PEM Ltd is an ISO9001:2015 registered company


Peak current

Dual range (10:1 )
60A peak to 60kA peak


±6.0V peak

High Frequency Bandwidth (-3dB)

1MHz (300mm coil),  600kHz (700mm coil)

Low Frequency Bandwidth (-3dB)

Varies with model type <0.5Hz (refer to datasheet)

Accuracy (typ.)

Calibrated to ±0.3% with conductor central in the Rogowski loop


Typical variation with conductor position ±1.0% of reading

Operating temperature range

0℃ to +40℃ (Integrator electronics)


–20℃ to +70℃ (Coil and cable)

Coil Lengths

300, 500, 700 or 1000mm (custom lengths available)

Coil thickness

8.5mm max.

Peak coil insulation

2kV peak

Cable Length (coil to integrator)

2.5m (custom lengths available)

Power Supply

Single 9V PP3 battery
Plus – 2.1/2.5mm socket for 12V to 24Vdc (±10%) DC supply)

Output load

> 100.0 k ohm (for rated accuracy)


  • 10:1 switch selectable current range
  •  Traceable calibration (certificate included)
  • Thin, clip-around, Rogowski coil for easy insertion into circuits with restricted access
  • Non- intrusive: Loads the circuit under test by only a few pH’s
  • No magnetic materials ensures excellent linearity < 0.05% full scale
  • Galvanically isolated measurement


Power (Quality) Measurements

The LFR has market leading low frequency performance, optimised to give minimal phase error from 45Hz to 20kHz and the lowest possible noise floor. It can be used with frequency analysers, digital multimeters and oscilloscopes to perform a thorough power quality audit. The thin, flexible coil is easy to install even where conductors have been tightly bundled or space is restricted making it easy to identify sources of power quality disturbances.

20A per div, 4ms per div Class 0.2 metering CT vs. the LFR
20A per div, 4ms per div
Class 0.2 metering CT vs. the LFR

The LFR has exceptionally low phase shift between 45Hz to 20kHz enabling the measurement of the fundamental frequency and up to the 400th harmonic with excellent accuracy. The wide bandwidth allows the user to recognise and quantify some common power quality issues including THD, power factor and ground currents. The high frequency (-3dB) bandwidth of up to 1MHz is sufficient to detect some transient power quality disturbances and noise including capacitor bank switching and equipment inrush.

For even more demanding power quality applications requiring a wider bandwidth PEM also offer the CWTLF range.

Leakage and Ground Currents

When used in combination with a digital multimeter the LFR can be used to detect ground and leakage currents. The flexible coil is easy to install around large individual and multiple conductors as well as conduit trunking. The LFR coil can be supplied in standard lengths up to 1m and two turns can be made around a conductor (for coil lengths >=700mm only) to double the measurement and improve the SNR ratio.

Quote Request LFR

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