Shunts replace transformers in large inverters

This series is intended for measuring phase currents of up to 20A through shunts on the circuit board.

Currents of up to 400A can be measured with precision and long-term stability using the jointly developed shunt modules in Semikron's Semitrans housing.

The PM240 high-performance parts for Sinamics G120 inverters make it possible to extend the current range of Isabellenhuette's Type BVR electron beam welded composite material precision resistors to 800A and power output to 132kW.

For this purpose, the resistance of shunts used in this area was reduced from 3mohm to 1mohm, and the module's layout was optimised.

The housing interior was also adapted to the terminal link design.

The isolated shunt installation, integration of three phases in one case and optimised power loss heat dissipation by a DCB substrate, as well as the module's size, were not changed.

Generally, the module's resilience and reliability were improved.

This module permits measuring currents of greater than 500A in industrial serial applications with four parallel SMD precision resistors with a deviation of less than 0.3 per cent in a temperature range between -25C and 125C.

At the same time, the system's drift throughout its life cycle is less than 0.5 per cent.

A prerequisite for this is the shunt's resistance alloy, which was optimised for this purpose.

Using shunt current measuring in this area of performance resulted in a very compact frequency inverter that may be used for operating engines, with a power rate of up to 132kW instead of the former 90kW.