Lem has introduced the CT family of current transducers for use in a range of safety applications including solar installations. The new transducers measure an AC or DC leakage current of 30mA or more (with possible spectral components up to 18 kHz) occurring when a solar panel is coupled to an earthed grid, or in failure modes such as a short circuit or earth fault. The connection of a solar panel to the grid raises concerns about the safety of the system and of any human contact with the system.

These differential current transducers have been specifically designed to meet the needs of modern solar topologies. They are PCB mountable, small (30 L x 30 H x 20 W mm), lightweight (25 g) components with an 11 mm diameter aperture for insertion of earth leakage wires. They can easily be integrated into the solar inverter and have been designed to make single-phase or three-phase differential current measurements on conductors carrying up to 30A/wire (AC or DC).

The CT 0.1-P, CT 0.2-P and CT 0.4-P safely measure currents with nominal values of 100, 200 and 400 mA respectively (1% typical accuracy at +25°C without offset), to trigger the safety system in the event of a high leakage current.

Lem’s CT range is also suitable for other applications, including medium power inverters for symmetry fault detection or in power sources for failure detection.

The transducers are CE marked, conform to the EN 50178 standard and are recognised for industrial applications.