Positive temperature coefficient start winding protection
AssigneeTecumseh Products Company
InventorRicky L. Bunch
Life of this patent
Estimating the term…
Abstract
A protection circuit for a permanent split capacitor motor includes a positive temperature coefficient (PTC) resistor in series with the auxiliary winding of the motor for protecting the auxiliary winding during normal operation. At a predetermined temperature anomaly due to over-current conditions in the windings, the PTC resistor will sharply increase its resistance to a point wherein no current will pass, effectively open circuiting the auxiliary winding from the power source, thereby protecting the windings from damage. A thermally responsive protector may also be used in conjunction with the PTC resistor for providing further over-current protection to both the main and auxiliary windings.
Claims9
An over-current protection device for a permanent split capacitor (PSC) motor having an auxiliary winding and a main winding, the auxiliary winding and the main winding connected in parallel, and a run capacitor connected in series with the auxiliary winding, the protection device comprising:
- a positive temperature coefficient (PTC) element connected in series with the auxiliary winding and in parallel with the main winding, said PTC element having an anomaly temperature that allows start-up current and normal operation current to flow through the auxiliary winding, but which substantially interrupts the current flow in the auxiliary winding when an over-current or fault current condition occurs by an increase in resistance due to a concurrent rise in temperature to effectively open-circuit the auxiliary winding from the current flow.
An over-current protection device for a permanent split capacitor (PSC) motor having an auxiliary winding and a main winding, the auxiliary winding and the main winding connected in parallel, and a run capacitor connected in series with the auxiliary winding, the protection device comprising:
- a positive temperature coefficient (PTC) element connected in series with the auxiliary winding and in parallel with the main winding;
- and
- a thermal protector for interrupting power to the motor, said thermal protector disposed in series with the main and auxiliary windings;
- said PTC element having an anomaly temperature that allows start-up current and normal operation current to flow through the auxiliary winding, but which substantially interrupts the current flow in the auxiliary winding when an over-current or fault current condition occurs by an increase in resistance due to a concurrent rise in temperature to effectively open-circuit the auxiliary winding from the current flow.
Dependencies are inferred from the claim text.