1 / 6
Index: WMGBMZC320
High-Current Fault Loop Impedance Meter
Technical Specification
  • Description

    Heavyweight for high-current measurements

    If you rely on reliable tools in your work, the Sonel MZC-320S high current short circuit loop impedance meter is a proven choice for you.

    In the work of every measuring engineer, electrician or technician, it is sometimes necessary to make multiple measurements. In such situations, many devices get blocked due to overheating, causing downtime. The Sonel MZC-320S short circuit loop impedance meter has been designed to perform flawlessly even in repeated measurements. The unit features an efficient ventilation system to minimise the cooling time of the short-circuit resistor. The instrument performs very well in the widely understood power industry and allows for multiple measurements of the short circuit loop impedance without the need for long downtimes.


    • Measurement of very low short circuit loop impedances (with resolution 0,1 mΩ) with a current of 130 A at 230 V; maximum 300 A at 500 V. 
    • Measurement with a current of 24 A at 230 V, maximum 27 A at 500 V with resolution 0,01 Ω.
    • Measurements in installations with rated voltages: 110/190 V, 115/200 V, 127/220 V, 220/380 V, 230/400 V, 240/415 V, 290/500 V and frequencies 45…65 Hz.
    • Ability to perform measurements in short circuit system: phase-phase, phase-PE, phase-N.
    • Differentiation between the phase voltage and the inter-phase voltage while calculating the short circuit current.
    • Ability to change the length of test lead (measurement with 2p method).
    • 4p (four-pole) method, test leads do not require calibration (measurement with current up to 300 A).
    • Measurement of resistance (RS) and reactance (XS) components.

    Additional features

    • Touch voltage and touch shock voltage measurement with resistor 1 kΩ).
    • AC voltage measurement in range 0…550 V.
    • Frequency measurement 45.0...65.0 Hz.
    • Memory of 990 measurement results, ability to transfer the data to a PC via USB and Bluetooth.
    • Power supply: rechargeable battery

    Reaching the areas unattainable to others

    In direct vicinity of transformers or in transformer stations, where the circuits are equipped with a high current protection (fuse-links with the rating of several hundred amperes, motor circuit breakers), fault currents may reach several hundreds of kilo-amps. Measurement of fault loop impedance in such networks requires a high-current meter, which is capable of measuring ZS values at the level of single milliohms. Our patented technical solution, which uses components not available in the commercial offer (unique fault resistor), enables us to offer the meter with perfect performance in such demanding conditions

    Measurements without compromise

    Commercially available fault loop impedance meters perform the measurements asymmetrically, i.e. using half-wave current. This solution introduces the transitional constant and DC constant, which does not always result in a linear behaviour of the transformer during the tests. This in turn, affects the accuracy of the results.

    MZC-320S high-current meter applies symmetrical current for measurements, which means that they use the full wave - thanks to the advanced design of the measuring system and fault circuit.


    The instrument is used for measurements in networks with the following rated voltage:

    • up to 500 V, where the prospective fault current may reach 69.4 kA, as measured according to EN 61557.

    These parameters make the meter perfect for tests and measurements at wind farms, high-speed rail and in facilities controlled by power companies.

  • Technical Specification
    Measurement functions Measurement range Display range Resolution Accuracy
    Voltage 0 V…550 V 0 V…550 V 1 V ±(2% m.v. + 2 digits)
    Frequency 45.0 Hz…65.0 Hz 45.0 Hz…65.0 Hz 0.1 Hz ±(0.1% m.v. + 1 digit)
    Short-circuit loop parameters
    4p method - high current measurement maximum current 300 A 7.2 mΩ…1999 mΩ acc. to EN 61557 0.0 mΩ…1999 mΩ from 0.1 mΩ ±(2% m.v. + 2 digits)
    2p method - standard current measurement maximum current 37 A from 0.13 Ω…199.9 Ω acc. to EN 61557 0.00 Ω…199.9 Ω from 0.01 Ω from ±(2% m.v. + 3 digits)
    Short-circuit current readings
    4p method - high current measurement network voltage 115 V…500 V up to 57.5 A…69.4 kA acc. to EN 61557 115.0 A…500 kA from 0.1 A Calculated on the basis of error for fault loop
    2p method - standard current measurement from 2.00 A…3.21 kA acc. to EN 61557 1.150 A…40.0 kA from 0.001 A Calculated on the basis of error for fault loop
    Touch and shock voltage
    4p method - high current measurement 0 V…100 V 0 V…100 V 1 V ±(10% m.v. + 2 digits)

    m.v. - measured value

  • Files