Thermal and overload protection for small electromotors

摘要

The bipolar thermal protection pile for monitoring the temp. and overload of small motors, especially for textile machine spindles and the like with a three-phase current supply, has an external PTC resistance (3) and a heating resistance (4) in series, directly next to the pile (2). They generate a heat to hold the bimetal switch (6) open until the current feed to the motor (7) is broken by the motor switch. Also claimed is an assembly with a thermal protection (2) coupled to an external PTC resistance (3) and resistance heater (4) in series.