| 摘要 |
An overload protection switch for an electric motor comprises a bimetallic switch-actuating element carrying a moving contact of the switch, a first terminal part having an extension which defines a mounting for the bimetal, and a second terminal part having an extension which mounts a fixed contact of the switch, the first and second terminal parts being received in a moulded plastics switch body portion. In contrast to prior art switches of this type where the terminal parts were manufactured of material having a low electrical resistance, the invention manufactures these parts of high resistance material selected such that under very high overload current levels the resistance heating in the terminal parts does not significantly determine the switching characteristics of the switch on account of the overwhelmingly predominant bimetallic heating, but towards the other end of the overload current scale the self-heating of the terminal parts significantly affects the switch operation.
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