Short circuit loop impedance meter MZC-310S

The MZC310S is a professional portable meter for testing electrical installations with over-current circuit breakers.

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Lightweight for high-current measurements

The Sonel MZC-310S meter is one of the most technically advanced short-circuit loop impedance measuring instruments available on the market.

With the use of the Sonel MZC-310S meter it is possible to test short circuit loop impedance in consumer networks as well as in distribution networks protected with high-current circuit breakers. At the same time as measuring the impedance, the shock and contact voltages can be measured. Where the condition for automatic power off cannot be satisfied, the facility may be authorised to operate on the basis of the voltage criterion.

The application of the four-wire method and the flow of the measuring current in the 150/280 A pulse determine the high precision of the performed test. This single device hides a multitude of measurement capabilities, making it appreciated by specialists in many fields. The meter complies with the requirements specified in the EN 61557 standard.


  • Measurement of very low short circuit loop impedances (with resolution 0,1 mΩ) with a current of 150 A at 230 V; maximum 280 A at 440 V.
  • Measurement with a current of 23 A at 230 V, maximum 42 A at 440 V with resolution 0,01 Ω.
  • Measurements in installations with rated voltages: 220/380 V and 230/400 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 280 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…440 V.
  • Frequency measurement 45.0…65.0 Hz.
  • Memory of 990 measurement results, ability to transfer the data to a PC via RS-232.
  • Power supply: rechargeable battery (5x LR14).

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 behavior of the transformer during the tests. This in turn, affects the accuracy of the results. MZC-310S high-current fault loop impedance meter applies symmetrical current for measurements, which means that it uses the full wave – thanks to the advanced design of the measuring system and fault circuit.


MZC-310S is used for measurements in low voltage systems (nominal voltage of 220/380 V or 230/400 V), where the prospective fault current may reach 55.7 kA (measured according to EN 61557).