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 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 overload protection system (OL) that has a speed of operation fast enough so that it will always trip before the power switch (MC) has had time to operate if the turn-on control means (ON) is operated under overload conditions. In one version, modules (OL1,OL2) are provided having PTC thermistor sensors (PTC1,PTC2) bonded to resistance heaters (H1,H2) connected in the motor power circuit (L1,L2,L3), these sensors being supplied from a current source (CT) and being effective to shunt current to a protective trip device (TR) upon occurrence of an overload condition, there being an ambient temperature compensating PTC themistor (PTC3) in series in the sensor circuit (OLC).

Abstract: An apparatus for controlling an airflow to a boiler or the like and maintaining a desired quantity thereof. The apparatus comprises a controller for generating a control signal of a level corresponding to a required airflow, a variable-frequency power supply for producing an output of a frequency corresponding to the control signal level so as to drive a ventilation-actuating motor, and means for detecting any deviation of the control signal level from a predetermined range and retaining the frequency of the motor-driving output at a proper value, whereby the airflow is maintained at or above a preset value.

Abstract: A computer-controlled switching apparatus for controlling power switching elements, wherein a microprocessor is connected by way of analog-digital converter means to at least one sensor for detecting the current consumption of the apparatus to be monitored, for example a motor or the like, and sequentially calculates characteristic data from the detected values, in accordance with various models, and compares said detected values to preselectible limit values, wherein the microprocessor includes a coding means which outputs the calculated values, with an address coding, by way of a transmission path, to a display means having a decoder.

Abstract: A digital overcurrent tripping arrangement having a nonpermanent digital memory. The arrangement further contains a resistor-capacitor stage that simulates the cooling-down process of a body. In accordance with the invention, a microprocessor uses a thermal excitation state digital value stored in the nonpermanent memory to calculate a digital normalized voltage value which is then stored in the nonpermanent digital memory. A digital comparator means within the microprocessor compares the digital normalized voltage value in the nonpermanent memory with a digital output of an analog-to-digital converter, the digital output corresponding to a voltage across the resistor-capacitor stage. If they agree, a charging switch between a current supply and the resistor-capacitor stage is opened.

Abstract: An improved electric power steering system is disclosed. The system includes an electric motor as a driving device. Input system torque, motor current flow and motor temperature are detected and used to control the motor to prevent premature failure of the system due to elevated temperatures in the vehicle engine compartment.

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 thermal model of an electric apparatus such as a transformer or motor, from which signals can be obtained representing temperatures of the conductors and of the adjacent core material, includes storing first and second values, respectively, representing conductor temperature and core material temperature. The magnitude of the current(s) in the apparatus is sensed and a digital signal representative thereof is added to the first value to represent heat generated in the conductors. Values are determined for both heat transferred from the conductors and heat transferred into the apparatus core based on the difference in the first and second values. The value representing heat transferred from the conductor is subtracted from the first value to give a new first value and the value representing heat transferred to the core is added to the second value.

Abstract: A drilling machine including an electric drill being selectively fixed at a desired angle with respect to a workpiece and a manual feed handle for moving the electric drill toward and away from the workpiece. A control circuit for the electric drill is provided having a sensor member being operatively connected in said control circuit for detecting a load applied on the electric drill. An alarm member is operatively connected in the control circuit for sending out a signal when a load signal exceeding a first reference level is detected. A switch is operatively connected in the control circuit for deenergizing said control circuit for the electric drill when a load signal exceeding a second reference level is detected.

Abstract: A power inverter including a converter unit for rectifying AC power into DC power, an inverter for inverting the DC power into AC power for driving a load apparatus, and a protection apparatus for protecting the load apparatus from being overloaded. The load protecting apparatus comprises current detecting means for detecting a current supplied to the inverter unit from the converter unit, a memory for storing a thermally limited operation time characteristic determined in consideration of cooling effect proper to the load apparatus, and an abnormality detecting circuit for producing an abnormality signal to stop the operation of the inverter unit when an accumulated value calculated on the basis of the current value detected by the current detector at a predetermined sampling interval exceeds the characteristic value previously stored in the memory. The load apparatus can be positively protected from overload notwithstanding variations in the output voltage and the output frequency of the power inverter.

Abstract: A delayed-action thermal relay, particularly for starting single-phase induction motors, comprises a case of insulating material, a first, a second, and a third terminal within the case, an actuator unit consisting of a heating element of a material with positive temperature coefficient and of a bimetal member, and first and second contacts that are normally closed carried by the bimetal and by the third terminal respectively, said actuator unit being forcibly and adjustably inserted between the first and second terminals.

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: The compressor motor controller of the present invention includes a hot motor detector adapted to be coupled to a plurality of temperature sensors for detecting an overtemperature condition of the compressor motor. The hot motor detector incorporates logic switching means for generating a motor control signal. A self diagnostic sensor is coupled to the hot motor detector for detecting an electrically shorted condition of the temperature sensors while a low voltage detector is coupled to the hot motor detector for sensing a low line voltage condition. Means are provided for protecting the compressor motor against the undesirable effects of short cycle operation while a lubricating oil pressure detector receives signals from a pressure transducer which are representative of oil pressure.

Abstract: Apparatus and method for protecting a squirrel cage induction motor against excessive temperatures which can occur in the rotor, provides a thermal model of the rotor. The thermal model has three regions A, B and C representing the starting portion of the rotor conductor, and the rotor core. The rotor is frequency sensitive and currents of higher frequency induced in the conductors tend to be in region A, and currents of lower frequency tend to be in region B. Equipment connected to the stator winding determines values for the positive and negative sequence components of the supply for the fundamental frequency and preferably also for the second and third harmonics present, and provides signals representing these values. Heat calculation circuitry receives the values for all the positive and negative sequence components and a signal representing speed, determines the currents that would be induced in regions A, B and C, and derives equivalent currents which would produce the same heat.

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: Electric resistor, including a PTC body being formed of ceramic material and having opposite poles, two opposite outer side surfaces being parallel to the longitudinal axis of the PTC body and two opposite end faces perpendicular to the outer side surfaces, the PTC body having rows of mutually parallel depressions formed in the end faces defining inner surfaces and leaving partitions therebetween, metal coatings disposed on the inner surfaces at the opposite poles and partitions, metal layers disposed on the outer side surfaces, and metal strips being disposed on the end faces interleaved in comb-fashion and being connected to the metal layers, defining current flow paths from the metal layers and metal strips through the partitions being perpendicular to the longitudinal axes of the depressions and electrically connecting the pole coatings of a respective row of depressions to each other, and a method for the manufacture thereof.

Abstract: A microprocessor controlled motor starter is utilized in which the short term temperature differential between the rotor bars and the rotor end bells is accounted for by the microprocessor-based system as a function of operator programmed stall time and locked rotor current for the particular rotor in question. The latter information is supplied to the operator by the manufacturer of the motor. The foregoing takes into account a slight deviation between the shutdown temperature, which should be predicted as a function of the manufacturer's data, and the actual shutdown temperature as expressed by an exponential. In the event that the short term temperature differential is exceeded, the microprocessor will enter a TRIP routine causing the motor controller to shut the motor down, thus preventing serious damage to the motor.

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 electric motor protection device comprising a body, an electric strip, a plunger, and pressure and temperature sensitive snap discs. The electric strip moves from a current conductive, closed position to a current nonconductive, open position when the current conducted through the strip exceeds a preset level. The plunger engages the electric strip also to move the strip from the closed position to the open position. The pressure and temperature discs move from normal positions to overcenter positions to engage the plunger and move the electric strip from the closed position to the open position, respectively, when the vapor pressure forces on the pressure disc and the temperature of the temperature disc exceed preset values.

Abstract: A motor starter, which may be microprocessor-controlled, is taught wherein a signal conditioning means is provided for receiving from the motor windings parallel inputs and motor bearings which are related to the motor winding and bearing temperatures and for operating on these parallel input signals in such a manner as to provide a single serial output signal for use by a control means to cause the motor control starting sequence or the normal motor run condition to be interrupted, for example, if any one of the temperatures is above a predetermined level.

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 protective thermal relay comprises a main heater for heating a snap-action element of a bimetallic switch to open the switch. The main heater is connected in series with the motor or other device to be protected by the relay. There is also an auxiliary heater for the bimetal element that is energized through an abnormal condition detection relay, e.g., a negative phase sequence detector, when the abnormal condition occurs. The auxiliary heater is a positive temperature coefficient type and will heat and hold the switch in the motor off mode as long as the negative phase sequence or other abnormal situation remains.

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 thermoswitch is physically located on a portion of the current supply connector between the current source and the exciter winding of the starter motor. The portion, constructed as a simple strip with flaps holding the thermostat, influences the temperature-dependent control portion of the thermoswitch according to heating in the armature, field winding, and brushes of the starter motor. The thermoswitch turns OFF the starter system by interrupting current supply to the kick-in starter relay.

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 method of assembling an electrical device including current relay means having housing means with at least one female terminal disposed therein and at least one switch means terminal extending exteriorly of the housing means. In this method, a solid state device is disposed at least adjacent the housing means, and the solid state device is connected in circuit relation between the at least one female terminal and the at least one switch means terminal.

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 combination starter-protector device adapted for removable mounting in electrical contacting engagement onto at least a pair of male terminals of a dielectric plug device secured to an apparatus housing. The combination starter-protector device has a casing, a PTCR disposed therein, and a switch in the casing for association in thermal coupling relation with the PTCR. A spring associated with the casing is adapted for releasable securing engagement with the apparatus housing so as to maintain the combination starter-protector device against displacement from the electrical contacting engagement thereof with the at least male terminal pair of the dielectric plug device when the combination starter-protector device is removably mounted thereto.

Abstract: This disclosure relates to apparatus and method for controlling and protecting an electric motor. A transmitter is coupled to the motor and to the power lines for generating pulses on the power lines in certain circumstances such as during an overheated motor condition. A control unit is coupled to the power lines and senses the pulses and monitors the power current magnitude in the lines. The unit compares the current level with previously established upper and lower limits. If the current level is outside the limits for a preset length of time, a fault condition exists and the motor is turned off for a length of time that depends upon the severity of the fault. The unit also turns off the motor upon the receipt of pulses from the transmitter when a certain number of pulses regularly recur. The unit includes indicators for displaying the nature of the fault.

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 hermetic electrical terminal construction adapted for connection to the outer housing of a hermetic motor compressor unit so that current may be carried to the compressor motor from an external source. The terminal comprises a body member welded or otherwise secured to the compressor outer housing and a plurality of conductor pins secured to and extending through the body member. Each of the conductor pins, which may be made of stainless steel, copper or other suitable material, comprises a first segment disposed within the housing, a second segment disposed outside the housing, and an intermediate segment connecting the first and second segments, the intermediate segment being disposed primarily within the body member. Electrical insulating and sealing material, such as glass or epoxy potting, surrounds the pin intermediate segment and forms a hermetic seal between the pin intermediate segment and the body member.

Abstract: A motor starting relay particularly adapted for use in starting single phase asynchronous motors comprises a resistor element of positive temperature coefficient of resistivity which is compactly arranged within a housing and engaged by electrical contact and terminals means of particular structure and of a material of relatively high thermal resistance in a novel way such that power dissipation or loss by the resistor is reduced to a very low level after it has performed its motor starting function but so that, at the same time, the resistor is adapted to cool more rapidly after interruption of motor operation to permit prompt motor restarting.

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: A housing is disclosed in which a positive temperature coefficient (PTC) of resistivity element is mounted a selected distance from but in thermal communication with a thermostatic switch also mounted within the housing.

Abstract: An automatic engine control system in which all solid state circuitry is isolated by open switches, open relay contacts and reversed biased diodes from either ground or the power supply during the standby state of the system. All solid state circuitry except that contained in the alarm circuitry is isolated during an alarm condition after shutdown of the engine has been effected. Novel circuitry is used for allowing the latching of a fault response relay while at the same time removing ground from other solid state circuitry. Further, the automatic engine starter and controller of the present invention utilizes unique and novel means for controlling the battery charger of the controlled engine and for initiating and resetting solid state timing circuitry.

Abstract: A three phase motor is constructed with each of the three phase windings thereof split in half so that the motor may be selectively connected for energization from either a relatively high or relatively low source. Motor protectors are provided in the form of a three pole automatic resetting overload relay means and two thermostatic switches. The heaters for the individual poles of the overload relay means are connected in series with a half section of the individual phase windings and do not have to be changed when either high or low voltage energization is selected for the motor. The thermostatic switches are embedded in two of the other three winding sections but electrically insulated from the motor winding. The control contact means of the overload relay means and the thermostatic switches are connected in series with the energizing coil of the electromagnet for the contact through which the motor is connected to its energizing source.

Abstract: A compact resistor device comprises a body of ceramic material of positive temperature coefficient of resistivity having a large number of passages extending through the body between opposite ends of the body, thereby forming very thin webs of the resistor material between adjacent passages. Coatings are formed on the resistor material along the inner walls of the passages to serve as ohmic contacts. The coatings in alternate passages are connected together at one end of the resistor device and the coatings in the other passages are connected together at the opposite end of the device to serve as device terminals. When the device terminals are connected to a power source, current flows through very thin webs of resistor material between ohmic contacts in adjacent body passages. The resistor device is particularly useful in current limiting applications requiring low, room-temperature resistance and in heat-exchanger applications where a fluid to be heated is directed through the passages.

Abstract: A control circuit is provided for a d.c. motor for sensing the temperature of the field winding and automatically reducing the temperature of the field winding when the temperature exceeds a preselected value.

Abstract: A prime mover adapted for energization to a preselected speed therefor across a power source. The prime mover has a pair of winding means for excitation so as to effect the energization of the prime mover generally to the preselected speed when it is energized across the power source. Means is provided in circuit relation with one of the winding means and the power source for inhibiting the excitation of the one winding means generally as the prime mover attains its preselected speed, and means is operable generally in response to the occurrence of a preselected condition with respect to the excitation of the other of the winding means for placing the inhibiting means in open circuit relation with the power source generally as the prime mover attains its preselected speed.A method of operating a prime mover, a method of interrupting the operation of means for inhibiting current flow therethrough, and a circuit are also disclosed.

Abstract: A disc type thermistor has a low melting point metal rod disposed between the thermistor and a metal spring. The spring places the rod in compressive contact with one surface of the thermistor. When the thermistor overheats, the rod melts and opens the circuit.

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: A circuit for monitoring the temperature of the contacts of an electrical switching device (such as a circuit breaker), comprises an electrical analogue circuit of the thermal characteristics of the switching device. The analogue circuit comprises electrical resistance and capacitance, interconnected so as to form an electrical model of the heat flow paths and capacitances respectively, in the switching device. The preferred embodiment also provides a temperature sensing device to introduce to the analogue circuit a voltage signal the magnitude of which is proportional to the exterior temperature of the switching device. The analogue circuit is connected in a series circuit relationship with a current controller. The current controller controls the amount of current flowing through the analogue circuit. The current controller is in turn controlled by a voltage control signal proportional to the amount of current being carried by the switching device.

Abstract: A controller for a motor or like electrical equipment. A thyristor in series with a power conductor that feeds the equipment and a control circuit for activating the gate terminal of the thyristor in accordance with the operating conditions of the equipment. The control circuit includes a transformer having a secondary winding connected to the gate terminal and means for varying the current flow in the secondary winding according to load demands. A three phase system having a thyristor in each conductor and a transformer secondary winding for each thyristor, which windings are on a common core.

Abstract: A self-powered solid state overload relay circuit having current transformers energized by conductors supplying current to a multiphase alternating current motor. The transformers have secondary windings connected to charge a capacitor with a voltage indicative of the magnitude of the maximum current in the motor windings. The circuit includes presetable impedance circuits which permit the circuit to be easily programmed to respond to a range of abnormal motor currents in the winding in motors of varying size and service factor ratings, components which are arranged to duplicate the operation of melting alloy and bimetal type overload relays in an automatic or in a trip-free manual reset mode, a light emitting device which visually indicates when the relay is in a tripped state, and components which cause the relay to be insensitive to ambient temperature variations.

Abstract: A system for protecting an electrical resistor, such as, for example, the dynamic braking resistor of a D.C. traction motor used in a diesel-electric locomotive, from burn-out in the event of a malfunction such as a cooling fan failure or air blockage, over-load, high ambient temperature, etc. Such protection is afforded by a noise-immune system that continuously monitors the resistor temperature and provides an output signal when the resistor temperature reaches a predetermined level above its normal operating temperatures short of an unsafe level. This is done by sensing the change in resistivity of the resistor with change in temperature thereof to provide a first control signal. A second control signal proportional to the current in the resistor is obtained and compared with the first control signal to obtain the aforesaid output signal proportional to the resistor temperature above ambient temperature.

Abstract: Apparatus for protecting the armature of an electric motor against excessive temperatures comprises a resiliently compressible and expansible pad in the armature circuit and composed of thermally sensitive, non-conductive material containing a plurality of conductive particles engageable with one another when the pad is in a compressed condition to establish a conductive path through the pad. The pad normally is maintained in a compressed, conductive condition by resilient force applying means which is of such resilience as to permit expansion of the pad in response to an increase in its temperature and render the pad non-conductive.

Abstract: Complete protection of a three-phase submersible pump motor, such as the type used downhole in an oil well, is obtained with a solid state digital logic control system that monitors each of the three phase currents and shuts the pump motor down if any of those phase currents indicates either an underload or overload condition. Time delays are introduced before shutdown to avoid undesired nuisance shutdowns otherwise caused by transient or momentary conditions. When the pump motor is de-energized in response to an underload condition, it is automatically restarted after a predetermined time delay. All of the delay functions are precisely determined by division of the power line frequency. Downhole pressure and temperature are also sensed and if they become excessive the motor is automatically de-energized to prevent overheating. The presence of an auxiliary physical condition, such as filling up a retaining tank, also causes the pump motor to be turned off.

Abstract: A circuit arrangement for protecting the remainder of a plurality of parallely operated transistors in the event any one of the transistors fails in a shorted condition. An open circuited failure has no adverse effect upon the operating circuit. Each transistor includes a "slow" turn-off diode with respect to the period of the input drive signal, coupled in series between a common input signal-feed point and the base of the transistor to which it is connected. The diodes are poled to block the collector B+ supply potential appearing at the base of the respective shorted transistor, thus preventing the B+ supply potential from being applied to the base of the remaining transistors. Additionally, a respective fusister is connected in series between each emitter and the load circuit line in order to thereafter remove the failed transistor from the circuit and to balance the transistor currents during normal operation.

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.