Over temperature protection in an electric motor

摘要

An electric motor incorporates a positive temperature coefficient resistor 18 between a supply terminal 14 and a brush 4. The resistor can be inserted from outside the motor through an aperture 17 in an end cap 2 so as to be held between leaf springs 15, 16. A body 19 of heat conducting material, also insertable from outside the end cap, can be provided and held against to resistor 18 to alter its effective thermal mass and so adjust its operating characteristics.