Short-circuit loop impedance tester with Calibration Certificate MZC-306 WMPLMZC306

Application and Measurement Range

This device is dedicated to precise measurement of short-circuit loop impedance in installations with a wide voltage range, making it a universal tool for both residential buildings and industrial applications. Thanks to its ability to operate in networks from 100 V up to 750 V, the instrument handles standard single-phase installations as well as more complex industrial circuits at 400/690 V. A key feature is the capability to perform measurements in circuits protected by residual current devices (RCD) without triggering them. By employing the low-current method (up to 36.7 A), the device achieves a resolution of 0.01 Ω even in installations with RCDs ≥30 mA, significantly accelerating acceptance tests and inspections by eliminating the need to manually reset protective devices after each test.

Functionality and Ergonomics

The device construction is designed with user comfort in the field in mind. The enclosure offers an IP54 protection rating, ensuring resistance to dust and water splashes, along with the mechanical durability required during installation work. A specially designed cover can be positioned in several settings, facilitating instrument transport and stabilizing it during measurements under various conditions. The built-in LCD display with LED backlighting ensures result readability even in low-light environments. The device automatically distinguishes between phase and line-to-line voltages and detects swapped L and N conductors, enhancing safety and reducing operator error risk. Additionally, the touch electrode function allows for quick verification of the protective conductor (PE) connection correctness before starting the actual measurement.

Measurement Accuracy and Analytical Capabilities

The instrument not only measures impedance but also calculates the expected short-circuit current (\(I_k\)) and displays the resistive (\(R_S\)) and reactive (\(X_S\)) components of the loop. Measurement accuracy depends on the selected operating range: for AC voltage, the basic error is ±(2% of reading + 4 digits) in the range up to 249.9 V and ±(2% of reading + 2 digits) for higher voltages up to 750 V. For loop impedance measurement using the low-current method (Z L-PE), the resolution reaches 0.01 Ω with an error of ±(4% of reading + 3 digits). If the measurement is performed without RCD tripping (Z L-PE RCD), the resolution is also 0.01 Ω, but the accuracy decreases to ±(6% of reading + 5 digits). These values enable precise assessment of installation status in accordance with the requirements of standard PN-EN 61557.

The device features memory allowing storage of up to 990 results (organized in banks of 99 records each), which can later be transferred to a computer via the USB interface. Power is supplied by four LR14 batteries or an optional rechargeable battery, guaranteeing performance of at least 5000 measurements on a single set of cells. The instrument meets the requirements of measurement category CAT IV 600 V / CAT III 1000 V and features double insulation in accordance with standard PN-EN 61010-1. The package includes a calibration certificate, which is essential for companies requiring regular metrological audits of their tools.