Abstract: A motor protection circuit includes a capacitance and resistance timing circuit together with temperature sensing facilities which are energized upon motor startup to terminate operation of a motor in the event of insufficient oil pressure or excessive heat. An oil pressure sensing switch is connected to the timing circuit to prevent its operation so long as sufficient oil pressure is sensed.

Abstract: A reversible electric motor is caused to modulate a load in response to an off-on condition responsive device, such as a thermostat. The thermostat completes an electric circuit through an electric heater which in turn supplies heat to a bimetal. The time constant of the bimetal and heater provides a modulating action to a three position motor control switch means which has a center open position. The motor provides a follow-up action through a cam or similar mechanism to rebalance and control an appropriate load, such as a temperature altering medium source.

Abstract: A temperature sensitive electronic switching arrangement has a casing with two terminals, one of which may be constituted by the casing. In the casing is a positive temperature coefficient resistor and associated trigger circuit. As the temperature rises, a point is reached at which the circuit between the casing terminals changes from a high resistance to a low resistance. The arrangement has many uses, particularly in road vehicles.

Abstract: A motor protection circuit employs a resistance bridge circuit with one side having multiple branches containing temperature responsive resistances for sensing an overheat condition in the motor. Semiconductor voltage sensing devices, such as high gain amplifiers, are responsive to voltages between a standard sensing node and each of the sensing nodes in the multiple branched side of the bridge circuit. Logic facilities respond to any of the sensing devices to operate switching facilities controlling energization of the motor. Additionally, the protection circuit may include a lubricating oil pressure responsive control which is not affected by power loss or spurious signals, and which may be controlled by the operation of a motor control switch.

Abstract: A motor protector for a split-phase motor having a starting switch, the arm of which is connected to the run winding and which moves from a first position in engagement with a first contact to energize the start winding into a second position in engagement with a second contact thereby to deenergize said start winding upon the motor attaining a predetermined starting speed. The protector includes a thermostatic element to be positioned in heat-exchange relationship with the motor windings and which is heated by the flow of electrical current therethrough. It has a first curvature position at ambient temperatures and moves to a second curvature position at an elevated predetermined temperature. The protector further includes a switch having contacts which are opened in response to movement of the thermostatic element into its second curvature position. The thermostatic element is serially connected with the contacts of the latter switch in a circuit between one terminal of an a.c.

Abstract: A solid state switch particularly useful in assisting in the starting of permanent split capacitor (PSC) motors is disclosed in which a semiconductive element is used to affect the starting torque of the motor. The semiconductive element is a disk-shaped member composed of material having a relatively low resistance at temperatures below an anomaly point and a steeply sloped positive temperature coefficient (PTC) of resistivity at temperatures above the anomaly. The PTC element is mounted within a casing which comprises two identical interfitting halves and is in electrical connection with members which are combination contacts and terminals. The terminals extend through the casing wall and are provided with contact portions which engage the PTC element along an annular portion of the element near the outer periphery thereof. One contact is provided with spring fingers adapted to react against a wall of the casing to provide desired contact force.

Abstract: A control system for a motor having a required oil pressure for the safe operation thereof, the system having a time delay switch for interconnecting an electrical source to the motor to operate the same each time the time delay switch is initially activated by being placed across the power source. The time delay switch has a time delay bimetal means that is adapted to move and open the switch if the oil pressure of the motor does not reach the required value within a predetermined time period from the initial activation of the time delay switch. An oil pressure responsive switch is operatively interconnected to the time delay bimetal means and to the motor to terminate the switch opening movement of the time delay bimetal means if the oil pressure reaches the predetermined value thereof during the predetermined time period so that the motor will be continuously operated as long as the system is not manually or automatically turned off or the oil pressure does not fall below the predetermined value thereof.