Protection device for electrical appliances, in particular electric motors, compressors and transformers

摘要

A protection device is provided for electric appliances suitable for selectively connecting an electric appliance to a power supply line. The protection device includes a metal plate member, a composite metal blade, an insulating block for supporting the metal plate member and the composite metal blade, and a compensating resistor made en bloc with the metal plate member.

主权项

1. A protection device for electric appliances, in particular electric motors, compressors and transformers, suitable for selectively connecting an electric appliance to a power supply line comprising:
a metal plate member having at a first end a stationary electrical contact and at a second end a first electric connection terminal; a composite metal blade having at a first end a movable electrical contact and at a second end a second electric connection terminal, said movable electrical contact making with said stationary electrical contact an electric switch having an opening position and a closing position, said composite metal blade being configured for deforming until snapping from the closing position to the opening position when temperature around said composite metal blade exceeds a higher temperature threshold value, and configured for deforming until snapping from the opening position to the closing position when the temperature around said composite metal blade falls below a lower temperature threshold value; an insulating block for supporting said metal plate member and said composite metal blade; and a compensating resistor made en bloc with said metal plate member between said stationary electrical contact and said first connection terminal, said insulating block being constrained to said metal plate element so that the latter projects cantilevered with respect to the insulating block itself leaving said compensating resistor free.