General
Enclosure diameter	20 mm

The MN73 current transformer from Chauvin Arnoux is a compact measuring device for precise detection of alternating currents in the range from very low to medium current strengths. The device is part of the MN series and is primarily used for measuring leakage and fault currents in electrical installations. With an encircling diameter of 20 mm, it is particularly suitable for use in tight or hard-to-reach locations where conventional measuring clamps would not fit. Measurement is performed contactlessly via the magnetic flux of the conductor being measured, with the device providing an output through a permanently attached cable with a 4-mm insulated plug. This ensures a secure and interference-free connection to external measuring instruments such as multimeters or power analysers.

Current transformer

The MN73 is a current transformer that converts alternating currents into a proportional alternating voltage signal. The conversion takes place via a turns ratio defined in two measurement ranges: 1 mA corresponds to 1 mV and 1 A corresponds to 10 mV. This linear relationship enables precise and reproducible measurement, with typical accuracy being ≤ 1 % in the lower range and ≤ 2 % in the upper range. The output signals are alternating voltages that can be directly connected to the inputs of measuring instruments.

Applications

The device is designed for use in industrial and commercial installations, particularly for diagnosing leakage currents in installations. It is frequently used in office and industrial facilities to locate fault currents indicating insulation defects or other electrical disturbances. The safety categories CAT III 600 V and CAT IV 300 V allow use in electrical installations with corresponding voltage classes, with the IEC 61010 standard defining safety requirements for measuring instruments.

Functions and equipment in detail

The MN73 features two measurement ranges: 10 mA to 2.4 A and 100 mA to 240 A. This division enables higher resolution in the lower range, which is important for precise detection of small currents such as leakage currents. The output is via a permanently mounted cable with a 4-mm insulated plug, ensuring a mechanically stable and electrically secure connection. The compact and ergonomic design facilitates handling, especially in tight installations.

Technology explained simply

A current transformer such as the MN73 operates on the principle of a transformer: the conductor to be measured is passed through the clamp, generating a magnetic flux that induces a proportional voltage signal in a secondary winding. The turns ratio of 1 mA/1 mV and 1 A/10 mV defines the scaling of the output signal. The accuracy of ≤ 1 % in the lower range and ≤ 2 % in the upper range ensures reliable measurement values. The output voltage is an alternating voltage that can be directly connected to the inputs of measuring instruments.

Compatibility and accessories

The MN73 is designed for use with multimeters and power analysers that have an alternating voltage input. The connection is made via the 4-mm insulated plug, which is standard in many measuring instruments.

Installation and mounting

Installation is performed by simply encircling the conductor to be measured with the clamp. No additional mounting or fastening is required. The clamp is placed directly on the conductor, with the maximum encircling diameter of 20 mm to be observed. Connection to the measuring instrument is via the permanently attached cable.

Operational advantages

The MN73 offers high precision in measuring small currents, making it particularly suitable for diagnosing leakage currents. The compact design and small encircling diameter enable use in tight installations. The safety categories CAT III 600 V and CAT IV 300 V ensure use in a wide range of installations. The use of a 4-mm insulated plug ensures reliable and interference-free data transmission.

Scope of delivery

The scope of delivery includes the MN73 current transformer and the operating instructions. The instructions are in German and contain technical data and operating instructions.

Safety standards

The device complies with the IEC 61010 standard and is approved for use in installations of safety categories CAT III 600 V and CAT IV 300 V. These standards define safety requirements for electrical measuring instruments and ensure safe operation under specified conditions.