Control circuit for a two speed single phase motor
AssigneeLennox Industries Inc.
InventorsDavid M. Pfarrer, Leonard J. Van Essen
Life of this patent
Estimating the term…
Abstract
A control circuit for a two-speed single-phase motor as used in a hermetic refrigerant compressor which includes means for preventing welding of the start relay contacts of the start relay means by electrical discharge from the run capacitor. In one aspect of the invention, a discharge path is provided for the run capacitor by switches and auxiliary contactor means. In another and preferred aspect of the invention, a negative temperature coefficient thermistor is used in series with and between the start capacitor means and the start relay contacts for limiting the current to the start windings from a source of power and for limiting the current discharged into the start capacitor means from the run capacitor after the motor is deenergized.
Claims7
For use with a single-phase two-speed motor comprising a main winding, a start winding means including a low speed start winding and a high speed start winding in circuit with the main winding and adapted to provide either a high speed operation or low speed operation, low-speed contactor means, high speed contactor means, start relay means, start capacitor means and run capacitor means, a thermistor in series with the start contacts of the start relay means for preventing welding of the start contacts of the start relay means, the start capacitor means being in parallel with the run capacitor means and the thermistor and start contacts are electrically disposed between the start capacitor means and the run capacitor means.
Dependencies are inferred from the claim text.