Sonel MZC-330S High-Current Fault Loop Impedance Meter

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Data Sheet MZC-330S/320S

SKU: WMGBMZC330 Categories: , Brand: Sonel


Heavy weight in high current measurements

Choose the Sonel MZC-330S high-current short-circuit loop impedance meter with efficient ventilation system for smooth and effective operation without downtime.

In case of multiple short-circuit loop impedance measurements, some measuring devices may get blocked. This problem does not affect the Sonel MZC-330S meter. To prevent blockages, the device is equipped with a special high performance ventilation system that significantly reduces the time required to cool the short-circuit resistor. The Sonel MZC-330S advanced high current meter is the right choice for professionals in the power, electrical, as well as installation and measurement industries. The device combines extensive measuring capabilities with high durability and resistance to harsh working conditions. A specially developed ventilation system translates into greater efficiency and significantly reduces working time.


  • 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 690 V. 
  • Measurement with a current of 24 A at 230 V, maximum 37 A at 690 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 400/690 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…750 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-330S 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 750 V, where the prospective fault current may reach 95,8 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.

Remote working is always the best solution

The instrument can be controlled remotely – all that is required is for the meter to be logged into the same Wi-Fi network as the controlling device, i.e. any device with a web browser. After calling up the virtual control panel in the browser, the user will be able to start the measurement from a convenient distance and then read out the results.

By the same means, he will gain access to the stored measurement results. Importantly, he or she will also be able to download them in the classic manner, i.e. via a USB connection.