KoCoS Blog

Saving of working time through simultaneous resistance determination at three measuring points

For switchgear in the medium-voltage and high-voltage level, the switchgear standard IEC 62271-1 requires a static resistance measurement of the main circuit in order to exclude an unacceptable heating of the current path.

Traditionally, the measurements are carried out one after the other and individually at each phase. The main circuit is supplied with 100 A direct current and the voltage drop is measured. If the measured value, i.e. the voltage drop is within the specified limits, the test is passed and the results can be recorded/stored. This measuring procedure is time-consuming as the three phases are tested one after the other.

To increase productivity and improve reliability, the measuring method for resistance and voltage drop measurement can be optimized with the PROMET R300 or R600.

The PROMET R300/R600 resistance measurement systems are equipped with three voltage measurement inputs, allowing parallel measurement at three measuring points, for example to measure the resistance of three main contacts statically.


In order to perform a simultaneous measurement of three main contacts, the test objects must be connected in series and provided with a test current connection. Since a four-wire measurement is carried out, it is important to ensure that the voltage connections are between the high current connections and that they are connected exactly at the points where the resistance is to be determined.

Connection example for a measurement on three test objects connected in series, e.g. three interrupter units.

In stand-alone mode, the three static resistance results with the measurement details (actual test current and voltage drop, measurement ranges etc.) can be stored in the measurement device.


The data stored in the device can be read out and managed with an easy-to-use PROMET software. The clearly displayed measurement results can also be output in a PDF test report or exported as CSV data.

The described simultaneous measuring method for the acquisition of three resistances thus saves working, changeover and measuring time!

As a further automation option, PROMET R300/R600 are equipped with interfaces for connection to the ACTAS 2.60 switchgear testing software. Resistance measurement can be conveniently integrated via the ACTAS test software. Even without an additional ACTAS test system, automated test sequences and a comprehensive analysis of the test results can be carried out without any problems.


The method is not only applicable in switchgear testing, but also in applications such as e.g. in the field of e-mobility, where several resistors have to be detected at the same time.

If you have further questions, please leave a comment or contact us directly.

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