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Optically Isolated Current Meter

Optically isolated current meter is suitable for the measurement of AC currents in HV and LV overhead conductors. The meter provides excellent electrical isolation of up to 100kV AC insuring maximum protection of the personnel operating the instrument.


  • On-line real time measurements
  • Non intrusive
  • Compact & light-weight design
  • Up to 100m optical isolation
  • Snaps in and out around conductor by push/pull action
  • Accurate and reliable
  • No conductive link between energized parts and the operator
  • Safe to measure current of up to 100kV overhead power conductors
  • Range 0-500
  • 0-500 mV DC output suitable for data-logging
  • Battery operated

Functionally the meter consists of the four main elements such as:

  • Conventional type LV current clamp adapter,
  • Electrical-to-optical conversion module,
  • Fiber optic cable,
  • Optical-to-electrical converter.

Elements 1) and 2) are physically located close to each other and are attached to the high voltage end of the operating stick (not included) via the "rising star" connector. Element number 4) is located at the operator end of the stick. The clamp adapter is fitted with a pair of guiding horns with half-spheres so that the overhead conductor can easily slide in and out through the adapter jaws.

The Output from the optical-to-electrical converter is a DC signal that can be displayed using any conventional multimeter with mV range. 1mV DC reading on the multimeter corresponds to 1A of AC line current with full-scale range of 0-500.

The output can also be interfaced with a data-logger for long term "load flow" monitoring.

Both, transmitter and receiver modules are powered by 9V batteries. The power consumption of each unit is such that the batteries can provide approximately 100 hours of continuous operation of the current meter. Accuracy of the meter is determined by the accuracy of the clamp adapter, which is +/- 2%.

Magshield offers a 12 months warranty on parts and labour provided that the meter is properly used and is adequately protected during storage and transportation.

The current meter is shipped fully tested and pre-calibrated for full-scale range of 0-500A.

The proper operation of the meter can be ensured if all optical plugs and sockets are well protected from dust, dirt and physical damage. It means that all the rubber protective covers supplied must be used when the meter is not operated.


Power: 2 x 9V Batteries (1 per receiver and transmitter unit)
Accuracy: 2% of full scale riding
Fiber Optic Cable: 10m of Multimode 62.5/125
Current range: 0-500A rms.
Receiver output: 0-500mV DC
Max. Withstand Voltage: 100kV (an adequately rated operating stick must be used)
Operating Frequency: 50/60Hz
Max Conducor Diameter: 45mm
Operating T degrees and RH range: -5 to 50 degrees C; 80%

Measuring Procedure

  • Assemble the unit for measurements by affixing the transmitter unit (light gray plastic box) to the clamp adapter
  • Connect all cables to the transmitter unit. Make sure all rubber covers are removed from the optical sockets and plugs.
  • Attach the other end of the optical cable to the receiver unit.
  • Connect a digital multimeter with mV DC range to the receiver unit and set it to 500mV range.
  • Switch "ON" both the clamp adapter and receiver unit.
  • Clamp a conductor of LV or HV power line by pushing the clamp adapter against the conductor
  • Read RMS value of current from the multimeter attached to the receiver unit (1mV correspond to 1A rms. of conductor current)

Note: As the optical link is not set for a DC current measurement the "DCA Zero Adj." knob should not be operated.

Low Battery: It is necessary to replace the battery when the "Low BAT" indicator of the transmitter unit is "ON". Replace receiver battery when the red LED is ether off or dim at power "ON".