Pump unit for heating or cooling circuit - uses frequency regulator to reduce rotation of pump motor upon detected overheating

摘要

The pump unit (1, 3) has its rotation rate controlled by varying the working frequency of a frequency regulator (4), supplying the pump electric drive motor (3). The pump unit (1, 3) and the frequency regulator (4) are combined, with the rotation reduced via the regulator (4) when an overheating condition is detected to half the normal rotation rate. - The thermal overload condition is detected by measuring the temp. of the drive motor stator winding, e.g. by measuring the electrical winding resistance.