Adjustable electronic potential relay
AssigneeSealed Unit Parts Co., Inc.
InventorAlexander Brodetsky
Life of this patent
Estimating the term…
Abstract
A starting circuit for a single-phase induction motor having a start capacitor, an auxiliary or start winding, and a run winding includes user adjustable pick-up voltage means to allow a user to select a pick-up voltage in the field to correspond to the pick-up voltage of a particular induction motor such that a relay disconnects the start winding from the power supply when the start winding voltage exceeds the selected pick-up voltage. Protective circuitry is provided including a timing circuit to protect from missetting of the pick-up voltage or when the motor will not start for any reason and a relay current circuit to control the current flowing in the relay to protect from high voltage overloading.
Claims25
A starting circuit for a single-phase induction motor having a start capacitor, a start winding and a run winding comprising:
- means for connecting the start capacitor, the start winding and the run winding of the motor to a power supply;
- relay means for connecting and disconnecting the start capacitor and the start winding from said power supply;
- and
- user adjustable pick-up voltage means for allowing a user to select a pick-up voltage in the field, said user adjustable pick-up voltage means being operative to activate said relay means to disconnect the start capacitor and the start winding from the power supply when the start winding voltage exceeds said selected pick-up voltage, and wherein the run winding remains connected to the power supply after said relay means is activated to allow continued operation of the motor after it is started.
A starting circuit for a single-phase induction motor having a start capacitor, a start winding and a run winding comprising:
- relay means for connecting and disconnecting the start capacitor and the start winding from a power supply, said relay means comprising a mechanical relay having a relay coil;
- user adjustable pick-up voltage means for allowing a user to select a pick-up voltage in the field, said user adjustable pick-up voltage means being operative to activate said mechanical relay to disconnect the start capacitor and the start winding from the power supply when the start winding voltage exceeds said selected pick-up voltage;
- time-based protection means for automatically activating said mechanical relay to disconnect the start capacitor and the start winding from the power supply after a predetermined amount of time to protect the motor against missetting of the selected pick-up voltage and when the motor will not start for any reason;
- and
- current control means for maintaining current flowing through said relay coil below a predetermined value to protect said mechanical relay from excessive current created by the rise in start winding voltage induced from the rise in voltage in the run winding.
A method of replacing a first starting circuit connected to an induction motor having a start capacitor, start winding, run winding and a given pick-up voltage at which the start capacitor and the start winding are to be disconnected from a power supply and the run winding is to remain connected to the power supply to allow continued operation of the motor after it is started, the first starting circuit having a fixed pick-up voltage rating corresponding to the given pick-up voltage of the motor, comprising the steps of:
- (a) removing the first starting circuit from the motor;
- (b) replacing the first starting circuit with a second starting circuit comprising relay means for connecting and disconnecting the start capacitor and the start winding from the power supply, and user adjustable pick-up voltage means for allowing a user to select a pick-up voltage in the field, said user adjustable pick-up voltage means being operative to activate said relay means to disconnect the start capacitor and the start winding from the power supply when the start winding voltage exceeds said selected pick-up voltage, and wherein the run winding remains connected to the power supply after said relay means is activated to allow continued operation of the motor after it is started;
- and
- (c) adjusting said pick-up voltage means in the field to correspond to the given pick-up voltage of the motor.
Dependencies are inferred from the claim text.