Abstract: In a vehicle window wiper system having an electric drive motor with high, low and common brushes, electric motor energizing apparatus and forward and reverse motor operation, an auto-resetting current limiting device provides non-sacrificial protection to motor windings and associated circuitry during the various modes of motor operation.

Abstract: A protective PTC device is heated by a heater PTC device or by a resistor to an elevated temperature greater than ambient but less than its switching temperature. The elevated temperature of the protective PTC device reduces its switching response time, and minimizes variations in such response time with variations in ambient temperature. The protective PTC device is connected in series with an electrical load to reduce current to a load when the protective PTC device is switched to its high-resistance state by a temperature increase resulting from overcurrent. The heater PTC device or the heater resistor may be in parallel or in series with the protective PTC device. The heater PTC device does not carry load current, but the heater resistor may be placed in series with the load and the protective PTC device so as to carry load current along with the protective PTC device.

Abstract: A method of locating a limit switch (10) on a compressor (12) utilizes thermography for determining the optimum location thereof. A thermograph is produced for normal and abnormal operating modes of the compressor (12). High temperature gradients in the thermograph indicate high rates of temperature increase during compressor failure modes for selecting an optimum location for the limit switch. A bimetal switch (10) is utilized to establish a cut-out temperature for preventing operation of the compressor (12) and a cut-in temperature lower than the cut-out temperature for automatically closing to resume operation of the compressor (12) when returned to normal temperatures.

Abstract: The present invention features a system and method for preventing overheating of a motor and/or power amplifier of a material handling vehicle by controlling the performance of the vehicle as a function of motor and/or power amplifier temperature. Temperature sensors are connected to the motor and power amplifier for determining their operating temperatures. A controller is connected to each temperature sensor and to the motor for controlling acceleration of the motor as a function of either or both temperatures, so that both the motor and the power amplifier will not overheat. In controlling acceleration of the motor, the invention provides a mechanism for changing acceleration by discrete steps or continuously according to a performance curve which may be linear or otherwise.

Abstract: A unipolar motor control system includes motor current regulation derived from monitoring battery voltage and motor temperature. The monitored battery voltage and motor temperature are inputs to a microprocessor control which has one or more look-up tables for developing an appropriate scaling factor that adjusts the voltage across the motor coils so that proper current magnitude is delivered to the motor.

Abstract: A control circuit for connecting a load to a voltage source includes an electronic holding circuit having latched and unlatched states. When latched, the electronic holding circuit connects the load to the voltage source. A thermal device responsive to excessive current demand by the load automatically places the holding circuit in its unlatched state, and disconnects the load from the voltage source.

Abstract: An electrically driving system for the rearview mirrors, wherein the incorporated motors are rotated normally or reversibly in response to the operation of a operational switch, thereby erecting or folding the mirror bodies. The system comprises a momentary operational switch, a relay circuit, a group of limit switches for cutting off the relay circuit and motor circuit respectively by detecting erected and folded positions of the mirror bodies, and a circuit for judging a folded state. When the operational switch is pushed, any folded mirror is detected within delay time of the circuit for judging a folded state. And only when both of the left and right mirror bodies are in the fold positions, the erecting relay is actuated to rotate the motors in the erecting direction.

Abstract: An electric motor includes a fan attached to the end of a rotor shaft extending through an opening in an end shield of the motor housing. The fan forces air about the housing to cool the motor components. A motor protector including a temperature sensor is connected to the stator windings and is sensitive to winding temperatures to shut off the motor when the temperatures exceed a predetermined level. A performed strip of material is positioned over the protector in a tent-like form to block flow of cooling air around the protector. Thus, the protector is kept sensitive to the winding temperature, the material block preventing the protector being influenced by the flow of cooling air within the motor.

Abstract: A motor protector and starter particularly suited for refrigeration compressor motors are mounted in the recess of a first housing portion with their resilient female sockets disposed in alignment with a pin receiving aperture. Leads are attached to terminals of the motor protector and starter components and directed through lead receiving apertures in the side wall of the first housing portion. A second housing portion is then snapped onto the first housing portion to provide a combination housing which can be installed on a compressor in a one-step on-line operation.

Abstract: The invention employs a stabilization circuit including a longitudinal branch with a series connection of a Zener diode and a resistor and in the other longitudinal branch with the series connection of a transistor and where the motor winding of the driving electric motor and the cross-branch is provided with a transistor and a corresponding series resistor. In the case of such an operating circuit without current control, the connection of the two modes of operation is advantageously achieved by operating a voltage divider, which comprises a series connection of a temperature dependent resistor element with a relatively small series resistor and a larger adjustable resistor, and in addition in each case again with a smaller series resistor, where this voltage divider influences directly the transistor which is connected in series with the winding.

Abstract: An electric motor armature current control circuit includes an electric motor with an armature in series with a protective device comprising a pair of polymer PTC elements connected in electrical series with the motor armature windings and in electrical parallel and thermal contact with each other. The first polymer PTC element, a temperature compensating element, has a very low cold resistance and a trip temperature higher than the maximum expected ambient temperature to which it is to be exposed in motor operation and generates heat in motor operation to trip to a much higher resistance and become self-regulating at that trip temperature. The second polymer PTC element is maintained at least at the trip temperature of the first through thermal contact and has a lower resistance at that temperature than the cold resistance of the first. Its trip temperature is higher so as to be reached only with excessive armature current.

Abstract: A thermistor circuit for sensing the temperature of an intermittent duty wound field motor is connected between the field and armature windings of the motor. When the field and armature winding currents are substantially zero (off duty), the resistance of the thermistor circuit is sampled by the motor controller, using the armature and field winding conductors.

Abstract: A device providing protection against over-currents in the windings of an electric motor having a rotor (3) and at least two windings (1, 2) comprises at least two parallel thermistors (17, 18) each mounted in series with at least one motor winding (1, 2).

Abstract: A motor protector having a thermostat metal element thermally coupled to an electrical motor in a refrigerator compressor motor system has a heater responsive to motor current thermally coupled to the thermostat metal element and has an improved component arrangement to provide locked rotor and ultimate trip protection for the motor without requiring calibration of the operating temperature for the protector after assembly or after incorporation in the motor system.

Abstract: A motor protector of the type having a snap acting thermostatic element is shown particularly adapted for use with compressor motors in which a conventional three pin header is mounted on the compressor casing to allow electrical energization of the motor. An improved heat transfer path is formed between the windings of the motor and the thermostatic element of the protector by suspending the protector from one of the motor pins in optimum heat conductive relation therewith and thermally separated from the compressor casing and any component mounted on the other two pins.

Abstract: A motor starter and protection circuit is disclosed wherein a bimetallic contact support supports moveable contacts which are electrically interconnected with stationary contacts during normal non-overload conditions. Current from the power support passes through the stationary moveable contact sets as well as the bimetallic contact support and through the main coil of the motor. A positive temperature coefficient resistance is mounted on the contact support in electrical interconnection therewith. Current passes through this resistance, a TRIAC, and the motor starting winding. Conduction of the TRIAC is controlled by sensing the current which passes through the main motor coil. Only when the current passing through the main coil is substantially greater than normal load current is the TRIAC gated into conduction. A phase control capacitance is interposed between the coil sensing current through the main coil of the motor and the TRIAC gate.

Abstract: A generalized real-time thermal model of an induction motor produces values indicative of the transient and steady state temperature condition of the motor. Each of these values is compared with respective predetermined limits and power to the motor is removed when any value exceeds its respective limit in order to prevent damage to the motor.

Abstract: An apparatus for predicting the remaining useful life of a motor uses the temperature and past history of the motor to determine the amount of insulation degradation for its prediction. The remaining useful life projection is provided at a display and may be used to trip the circuit breakers supplying power to the motor when projected life is shorter than the expected life or may be used to issue a warning that the rate of motor degradation exceeds the rate necessary to achieve the expected life for the motor.Motor protection is provided by tripping the circuit breakers supplying power to the motor before the actual temperature of the motor windings exceeds the temperature at which catastrophic and irreversible insulation failure would occur while not tripping the breakers for momentary transients.

Abstract: A motor protector of the type having a snap acting thermostatic element is shown particularly adapted for use with compressor motors in which a conventional three pin header is mounted on the compressor casing to allow electrical energization of the motor. An improved heat transfer path is formed between the windings of the motor and the thermostatic element of the protector by suspending the protector from one of the motor pins in optimum heat conductive relation therewith and thermally separated from the compressor casing and any component mounted on the other two pins.

Abstract: A supply and protection unit for a hermetic compressor of a thermostatically regulated refrigerator comprising an electrically insulating support body (3) adapted to be fixed to the casing of the compressor (P); said support body being provided with cavities (3a, 3b, 3c, 3d and 3e) opening at one of its faces intended to face towards the compressor for slidably and removably inserting therein of a pair of electrical devices (1, 2) and connection means thereof to be supported against the compressor casing, one of said devices being a thermally operated protection switch (1) and the other being a resistor (2) with a positive temperature coefficient.

Abstract: An overload protection arrangement for an electric motor, especially of a hand-held power tool, includes an electronic speed of rotation control arrangement which is, in turn, controlled by an overload circuitry which includes a positive temperature coefficient resistor situated in the winding of the electric motor and incorporated in a voltage divider. The output of the PTC-resistor is amplified by an amplifier and, when the temperature of the winding increases above an acceptable level, the maximum current which can be drawn by the electric motor is reduced to a level at which the winding cannot burn out even if the rotor of the electric motor is blocked. If the rotor can rotate freely, the speed of rotation thereof even at the reduced power input will be sufficient to assure rapid cooling of the device powered by the electric motor. A time-delay member consisting of a capacitor and a resistor is arranged in parallel with the operational amplifier.

Abstract: A combination starter-protector device for a winding circuit of a dynamoelectric motor comprises a housing structure having a perforated wall dividing the interior of the housing structure into starter and protector compartments. The starter compartment accommodates therein a positive temperature coefficient thermistor while the protector compartment accommodates therein a bimetal switch. The housing structure has two sets of terminals, one set of the terminals being adapted to be connected to the winding circuit of the motor whereas the other set of the terminals are adapted to be connected to a power source. The distance between the thermistor and the bimetal switch may be adjustable by the employment of a spacer element.

Abstract: A circuit, safe against an overload, for incrementally varying the power to an electric blower motor used for heating, ventilating and conditioning vehicles, having a PTC resistor in series with other series resistors in the circuit.

Abstract: A method of assembling a combination starter-protector device and mounting it in a preselected assembly position onto at least a pair of plug terminals associated with a housing having a dynamoelectric machine arranged therein and with the at least plug terminal pair connected in circuit relation with a winding circuit of the dynamoelectric machine. The combination starter-protector device includes a pair of separable casing members, a PTCR, an overload protector, and at least a pair of female terminals. In this method, the PTCR, the protector device and the at least female terminal pair are enclosed within the casing members, and a resilient means is releasably secured generally about a major peripheral portion of the casing members for retaining them against separation.

Abstract: Overload protection for a multispeed motor is provided in the form of a plurality of line break motor protectors positioned in good heat transfer relation with the motor windings and having heating elements in circuit with the motor windings to be responsive to excessive winding current and/or excessive winding temperature to disable the windings. Certain of the line break motor protectors are operational in more than one motor speed configuration. The line break motor protectors may be of the self-resetting temperature sensing variety and circuitry is included to insure that the motor does not restart until all protectors are reset subsequent to an overload condition.

Abstract: A releasable combination of a separable starter device and a separable protector device adapted for connection in circuit relation with a dynamoelectric machine. A PTCR (positive temperature coefficient resistor) in the starter device and a switch means in the protector device are adapted for association in thermal coupling relation when the starter device and the protector device are in the releasable combination thereof. One of the starter device and the protector device includes yieldable means extending generally circumferentially about at least a major circumferential portion of a part of the other of the starter device and the protector device for releasable engagement therewith so as to releasably maintain the starter device and the protector device against separation from the releasable combination thereof.A method of assembling a releasable combination of a starter device and a protector device is also disclosed.

Abstract: A motor protection device is provided that monitors motor currents and motor temperatures and provides protective functions whose characteristics are based on field settable data and motor operating conditions. The protective functions provided are overtemperature, overload, instantaneous overcurrent, ground fault, phase unbalance, and phase reversal. Field settable data is entered by means of a keyboard and consists of motor trip points for the protective functions, and motor and system parameters.

Abstract: A protection system for a dynamoelectric machine providing a plurality of protective functions comprises a module having as a first function over temperature protection including thermal sensors adapted to be placed in heat transfer relation with the windings of the machine. The sensors which may be connected in series or in parallel are connected to a sensing circuit provided with shorted sensor protection. When connected in parallel a channel is provided for each sensor and is isolated from one another. Other functions include a minimum off delay timer which prevents rapid cycling of the machine.

Abstract: A motor overheating protection circuit includes an enabling circuit which responds to a trigger signal provided by a reset circuit upon application of power to the protection circuit to enable a motor drive circuit to effect energization of the motor. A temperature sensing circuit provides a control signal indicative of the temperature of the motor, and should the control signal exceed the set point of a threshold detecting circuit of the enabling circuit, indicative of overheating of the motor, the enabling circuit inhibits the motor drive circuit deenergizing the motor. Once the motor has been deenergized as the result of an overheating condition, the reset circuit maintains the enabling circuit locked out until the protection circuit is deactivated and then reactivated.

Abstract: A refrigerant compressor of the type driven by a single phase motor capable of operating at a low speed and a high speed. The motor, including four separate windings, a first set of high-speed two-pole auxiliary and main windings, and a second set of low-speed four-pole auxiliary and main windings all wound on the same stator core. Each set of windings is provided with independent line break protectors that enable each set of windings and protector to be optimized without affecting the other. A mandatory low-speed start system is incorporated that insures initial low-speed start even when conditions require high speed operation. Speed switching from one speed to the other is accomplished in the present system while the motor is running without causing interruption of compressor operation.

Abstract: Method and apparatus for monitoring a plurality of thermal parameters and the pressure related work load of a motor-compressor unit utilized in a heat pump system and providing protection for the motor-compressor by turning off the system for time periods dependent upon which parameter caused the system to be turned off.

Abstract: An electrical control having a relay device, a solid state starter device and an overload protector device predeterminately arranged therein and connected in circuit relation.

Abstract: Mining equipment of the type operably dependent on the voltage and/or the phase of electric current is isolated from electric supply mains by an OFF switch in a control circuit before a current supply relay drops out. The OFF switch and an ON switch are coupled in a monitoring conductor which supplies current to a photo-electronic coupler. An output signal from the coupler is delivered to a battery fed integrator to provide a control signal to an output relay for a switch in the current supply line on mining equipment. The ON switch is bridged by a normally closed switch coupled to a relay which is responsive to operating current fed to the machine. In a second embodiment, thermal sensing elements for motor windings on the machine provide a signal to battery fed relays to open a normally closed switch in a circuit bridging the photo-electronic coupler.

Abstract: A relay device adapted to be removably mounted in plug-on circuit relation with a pair of male terminals. The relay device has a pair of separable housing members releasably secured to each other with a pair of female terminals disposed so as to be generally retained therewithin, and a pair of means is provided in each of the housing members for the passage of the male terminal pairs into electrical contacting engagement with the female terminal pair. A pair of means on one of the housing members is associated with the passage means pair thereof for holding engagement with at least one of the female terminal pair and the male terminal pair so as to prevent the displacement of the one housing member from the female terminal pair in the event of at least a partial separation of the housing member pair when the female terminal pair is in the electrical contacting engagement with the male terminal pair.

Abstract: A combination relay-starter electrical device is adapted for connection in circuit relation with a winding circuit of a prime mover. The electrical device has a pair of terminal means adapted for the connection in the circuit relation with the prime mover winding circuit, and coil means adapted for electrical energization. Means arranged in magnetic coupling relation with the coil means is operable generally for switching between a circuit completing position and a circuit interrupting position upon the energization of the coil means, and means is provided for housing the terminal means, the coil means and the switching means. A solid state device associated with the housing means is connected in circuit relation between the switching means and one of the terminal means so as to be de-energized when the switching means is in its circuit interrupting position.Another electrical device is also disclosed.

Abstract: A method of protecting auxiliary winding means and main winding means in a winding circuit of a dynamoelectric machine in the event of a current overload. In this method, means is actuated in response to a preselected thermal condition accompanying the current overload for interrupting the winding circuit. Heat is transmitted from means for controlling starting of the dynamoelectric machine to the interrupting means for generally maintaining the winding circuit effectively interrupted for at least a predetermined period, and the starting controlling means is operable generally in response to current flow therethrough to increase its resistance generally as a function of its temperature for impeding the current flow therethrough to the auxiliary winding means at a preselected speed of the dynamoelectric machine.A combination starter-protector device, a method of operating a dynamoelectric machine, and a circuit are also disclosed.

Abstract: The disclosure relates to a protection system for electric motors and the like wherein a plurality of condition responsive PTC impedances are utilized in a bridge circuit to sense predetermined changes in the condition being sensed and proceed to interrupt current flow to a motor or the like being protected. The protection circuit is capable of sensing short circuits or impedances below a predetermined minimum across the sensors to thereby provide an alarm condition also. On the occurrence of the alarm condition, a lockout circuit is energized to prevent application of power to the motor, etc. until after power has been removed from the entire electric circuit and then reapplied thereto. The protection circuit of the present disclosure is also capable of either automatic or manual reset. There is also provided a pop-up flag and remote overload light which can be operated upon sensing of an alarm condition.

Abstract: A circuit is shown useful to protect dynamoelectric machines from overtemperature conditions. The circuit comprises first and second tuned circuits coupled to the power lines of the dynamoelectric machine along with an oscillator for injecting a selected frequency signal in the line and a detector for detecting the signal when the tuned circuits are resonant. A thermally responsive switch comprising an electromechanical bimetal switch or a solid state PTC or NTC switch is adapted to be disposed in heat conductive relation with the dynamoelectric machine and is electrically coupled to one of the tuned circuits so that the temperatures below a selected level the switch will be in one state, e.g. a low impedance state, precluding resonance while at temperatures above the selected level the switch will be in an opposite state, e.g. a high impedance state, permitting resonance.

Abstract: A circuit useful to protect motors and other dynamoelectric machines from overtemperature conditions caused by a fault condition such as locked rotor, overcurrent, or the like. The circuit comprises first and second tuned branch circuits coupled to the power lines of the motor or other machine along with an oscillator circuit and detector circuit and a switch to change the effective impedance of one of the tuned circuits. The tuned circuits each includes a series connected inductance and capacitance while the switch, which can be an electro-mechanical device such as a heat responsive thermostatic switch, or a solid state switch such as an NTC or PTC thermistor is connected around one of the components of one of the tuned circuits. The oscillator may be a conventional one adapted to provide a selected frequency, preferably high relative to that of the motor power supply.

Abstract: A motor control circuit for controlling the operation of a motor having main running-speed windings and also start-up windings includes a fixed time delay circuit to energize the main windings after a time delay following energization of the startup windings. In addition a lock-out circuit is provided to prevent re-start of the circuit following a particular fault condition.

Abstract: A rotary transformer having a stator and a rotor is energized by a power supply at commercial power frequency; sensors are located on the rotary part of the machine and provide sensing output signals, at discrete threshold levels, to a threshold circuit which, in accordance with the sensed signals, provides loading on the transformer secondary in discrete steps; the loading on the secondary is reflected into the primary and sensed to provide, selectively, alarm or stop-motion signals if operating parameters, typically temperature, as sensed by the sensors, reach levels necessitating an alarm or even a stop-motion signal.

Abstract: The disclosure describes a refrigerant compressor of the type driven by a motor capable of operating at a low speed and a high speed, the motor including first, second and third stator coils. First, second and third temperature sensors are located adjacent the first, second and third stator coils, respectively, for detecting any change in temperature of the coils. If the temperature of any of the stator coils exceeds a predetermined value, a control device operates a switch in a pilot circuit that turns off the motor before damage from excessive heat can occur. A unique contactor assembly utilizing both electrical and mechanical interlocks interconnects the stator coils to provide two speed operation.

Abstract: A method of assembling a temperature responsive resistance member within a pair of separable housings. This method includes the steps of: mounting the temperature responsive resistance member in both supporting engagement and electrical contacting engagement between a pair of electrical terminals; and joining the separable housings against displacement so that the temperature responsive resistance member in both the supporting engagement and the electrical contacting engagement with the terminals is disposed within the housings in predetermined spaced relation therewith with portions of the terminals extending exteriorly of the housings.

Abstract: A motor protection circuit has a current sensing means connected in series with a contactor winding energization circuit for sensing current flow to initiate operation of a delay after break circuit or to maintain an oil pressure protection circuit unoperated.

Abstract: A control circuit for a motor usable in a refrigeration system has a variety of condition sensors including means to sense a low refrigerant pressure and timing means to override the sensing of low refrigerant pressure for a time period during motor start-up. A lockout circuit prevents re-start of the motor following a fault condition.

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 combination starting and protecting device particularly useful with split phase motors such as those used with refrigeration compressors is disclosed in which an element of material having a positive temperature coefficient (PTC) of resistivity characteristic and a thermally responsive switch are disposed in the same housing. A thermal coupling of a preselected value between the PTC element and the thermally responsive switch is provided so that a desired reset or "off" time is obtained for the thermally responsive switch without affecting the "on" time.