Protection circuit for DC shunt-wound motor - has two field winding sections with separate terminals and interrupts armature current if speed increase is too large

摘要

The circuit protects d.c. shunt-wound motors against inadmissible speed increaes. The motor's (10) field winding is divided into two subwindings (14, 16) with separate supply points. At least one of the subwindings has a current monitor (26) to initiate the disconnection of the armature current when this subwinding's excitation current drops below a given limit. The excitation current is regulated by a control circuit.