Title:
PROTECTIVE DEVICE AGAINST THERMAL OVERLOAD FOR A SMALL HIGH-HEAT-LOAD ELECTRIC MOTOR
Document Type and Number:
WIPO Patent Application WO/1995/027302
Kind Code:
A1
Abstract:
A device (1) for protecting a small high-heat load electric motor against thermal overload having a break contact (6) in the motor power supply circuit actuated so as to break at a certain heat load by a bimetal component (10) secured to a support (3), in which the break contact (6), the bimetal component (10) and the support (3) are electrically connected in series, are in a certain mutual relationship with respect to the electrical resistance and the heat-storage behaviour and are arranged spatially in parallel overlapping array over a wide area. In order to improve the protective effect by limiting the brush and winding temperature rises even with the motor in a continuing state of overload caused by a fault and to improve the duration of use of the motors over the whole operating temperature and voltage range for the usable short-term overload condition, the relations between the electrical resistances and the heat storage capacity of the bimetal component (10) and the support (3) designed as a large-area heat radiator are selected in such a way that the stop time determined on the initial switch-on of the motor and the first heat-overload switch-off, with continuing overload and constant current, sets an ever shorter switch-on period for subsequent switching cycles and an increasing ratio between switch-off and switch-on period.
Inventors:
Dieter, Rögelein
Application Number:
PCT/DE1995/000464
Publication Date:
October 12, 1995
Filing Date:
April 05, 1995
Export Citation:
Assignee:
Dieter, Rögelein
International Classes:
H01H37/54; H01H81/02; (IPC1-7): H01H81/02
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