Abstract: A disk drive has a microprocessor, a digital controller chip, and an analog power chip, and a multi-winding spindle motor. The power chip operates under gross and fine control to connect and disconnect, during ON and OFF phases, a supply voltage to each winding on a PWM basis. The magnitude of the supply voltage and the temperature of the power chip vary. The microprocessor sends a digital control signal to the controller chip for gross control. The controller chip sends a PWM signal to the power chip for fine control. The power chip has pins for receiving the supply voltage, for sending a modulated signal to the controller chip; and for receiving the PWM signal from the controller chip.

Abstract: A PTC thermistor comprising a ceramic body having positive temperature coefficient resistivity, a pair of electrode layers provided on both major surfaces of the ceramic body so as to be opposed to each other with the ceramic body interposed therebetween, a pair of metal terminals electrically connected to the electrode layers, and a resin molded portion provided so as to cover side surfaces of the ceramic body and side surfaces of the electrode layers, the metal terminal having a connecting plate electrically connected to the electrode layer and a terminal plate opposed to the connecting plate so that a space is formed between the terminal plate and the connecting plate and connected to the connecting plate by a linking portion, and the resin molded portion being so formed as to expose an outer side surface of the terminal plate of the metal terminal and fill the space between the connecting plate and the terminal plate of the metal terminal.

Abstract: Apparatus which automates the collection of motor temperature, flux and shaft current data for proactive motor maintenance. Motor speed is determined by an analysis of the flux frequency spectrum, and motor load is determined based on speed, from which a normalized thermal parameter is then determined. From a spectrum analysis of magnetic flux signals a set of peaks each characterized by a frequency and an amplitude is found, and a subset of peaks is identified in accordance with predetermined identity criteria for purposes of comparison. Temperature, magnetic flux and shaft current data are trended to provide early indications of degradation, as well as for recognizing faults.

Abstract: The method and the arrangement for temperature monitoring of universal motors based upon a resistance measurement of a field winding, wherein a DC current component of low magnitude is superimposed upon the motor current for elimination of the complex values of the AC current impedance, and wherein the voltage drop in the field winding is amplified and freed from the AC voltage component and is compared as a DC voltage component proportional to the ohmic resistance of the field winding to a temperature independent DC voltage component, which is obtained in an analogous manner from a current measuring shunt, through which the motor AC current, including the superimposed DC current component, flows.

Abstract: A pump overload control assembly is for use with an electric motor driven pump in a water pumping system. The assembly includes a pump overload control device coupled to a fluid responsive switch, thereby forming a pump overload control circuit that interrupts the current flow to the motor in response to an overload of current flow to the motor. The pump overload control device includes a resettable overload protector and indicator mechanism that visually indicates when an overload has occurred and breaks the current flow through the circuit, for example, in response to heat generated from the overload current flow. The fluid responsive switch opens and closes the circuit in response to the fluid being pumped to an external source, for example, when the fluid pressure level falls below or rises above a predetermined pressure level.

Abstract: A thermal protector for a hermetic electrically-driven compressor includes a thermal switch and a cluster socket. The protector is mounted inside a compressor housing on a terminal assembly mounted in a wall of the compressor housing. A casing of the thermal switch and a header plate hermetically closing an open end of the casing integrally form a flange on the peripheral edges when the header plate is secured to the casing. The thermal switch has two terminals one of which is provided with a receptacle into which one of terminal pins of the terminal assembly is fitted, and the other terminal is connected to a common lead wire of a compressor motor. The cluster socket has a plurality of terminal cavities for connecting windings of the motor to the terminal assembly. A body of the socket has a face having a pair of holding portions for holding the flange. Each holding portion has a hook-shaped portion at an end.

Abstract: A method and apparatus is disclosed or determining the remanent noise in a magnetic medium by DC saturation of a region thereof and measurement of the remaining DC magnetization. Conventional recording transducers may be used to determine the remanent noise. Upon determination, the remanent noise may then be compensated for in either or both of the record and playback modes for all varieties of magnetic media including, videotapes, cassette tapes, etc.

Abstract: This invention concerns an electronic thermal protection device adapted to interrupt the power supply on a multiphase line comprising a temperature detector including a resistive element thermally coupled to a temperature sensor that is connected to a digital processing circuit adapted to outputt a control order as a function of the overload detected by the temperature sensor. The temperature detector resistive element is connected to various rectifiers, each powered by a current transformer installed on one line wire such that the sum of the currents delivered by the rectifiers flows in the resistive element.

Abstract: An electronic motor protection system is shown having a power supply usable with multivoltage supplies and providing protection from over-temperature conditions caused by various fault conditions. The system also has optional features of a time delay for re-energization and for low voltage protection. The system is mounted on a circuit board and encased in potting material which also locks the two housing parts together. A miswiring feature is also provided to prevent connecting line voltage to the control circuit or sensor terminals.

Abstract: The present invention relates to a resistor device for controlling a rotational speed of a motor which has no directional property and provides a convenient setting. A resistance unit is positioned which includes at least four connecting points connected to connecting terminals at an upper predetermined position of a housing, and a heat sink having at least four supporting legs is provided to form passing paths open in all directions on the housing. Also, the resistance unit is adhered on the heat sink through an insulating layer, a second heat sink corresponding to the first heat sink is adhered on the resistance unit through the insulating layer, and short-circuit means having a soldered portion to be fused at a predetermined temperature upon an overloading of the motor is provided between the resistance unit and any one terminal.

Abstract: A electronic motor protection system is shown having a power supply (12) usable with multivoltage supplies and providing protection from over-temperature conditions caused by various fault conditions. The system also has optional features of a time delay (20) for re-energization and for low voltage protection (22). The system is mounted on a circuit board and encased in potting material which also locks two housing parts together (30, 34). A miswiring feature is also provided to prevent connecting line voltage to the control circuit or sensor terminals.

Abstract: An apparatus for thermal protection of an electric motor is provided, including a monitoring device for generating a signal representative of the current in a conductor supplying electrical power to the electric motor. A control circuit processes the current signal and utilizes the processed signal and motor thermal parameters, including the thermal resistance and thermal capacitance of the rotor, to generate signals representative of the temperature of at least the rotor. A comparator circuit, which may be part of the control circuit, compares the temperature signals to reference maximum temperature signals and produces a control signal when the temperature signals and reference signals satisfy a predetermined relationship. The control signal may be applied to a contactor to interrupt current to the motor. A method for thermal protection of an electric motor is also provided, including thermal modeling of the rotor temperature.

Abstract: An integrated power module combining drivers and power devices includes a diagnosis module integrated with or connected to the integrated power module. That includes protectors. The protectors provides protection against power device failure, transistor stack failure, gate drive failure, power failure, and other conditions. In a first level of diagnosis and protection, a gate driver is responsive to hard faults, such as short circuit and under voltage conditions, to disenable the power devices, for example, switching transistors of an inverter. In addition, the first level of protection includes soft faults, such as detection of overcurrent and over temperature in the power device, conditions that are merely reported to the controller, whereby the number and frequency of the events can be monitored. The second level of protection also provided by the diagnostic module may include power interlock to ensure that full power is being delivered to the integrated power module.

Abstract: The electric motor is part of an electro-mechanical actuating system that is especially applicable to power assisted automotive steering systems.A phase for monitoring the cooling of the electric motor is carried out when the motor is inoperative in order to produce a value for a restarting temperature. This value is used during an electrical motor thermal control phase when the motor is operative. This prevents the motor from exceeding a maximum permissible temperature.

Abstract: A thermal protector for a hermetic electrically-driven compressor including a hermetically sealed housing in which a power-supply terminal, an electric motor and a compressor are enclosed with a predetermined amount of refrigerant gas is disclosed. The thermal protector includes a thermally responsive switch having first and second lead terminal pins for securing first and second connecting terminals respectively and a holder formed from an electrically insulating material and including first, second and third cavities. Each of the first and second cavities has an opening in its one side. The first cavity accommodates the thermally responsive switch while the second cavity accommodates a secured portion between the lead terminal and the connecting terminal with a hardenable electrically insulating filler filling up the second cavity. Alternatively, the second connecting terminal is secured to a wall of the holder by an insert molding so as to extend through the wall, instead of use of the filler.

Abstract: An efficient fan drive circuit to drive a variable fan used in a power supply of a personal computer system. The fan drive circuit uses a diode to establish the minimum fan speed during operation in the normal temperature range. The bleeder resistor normally coupled between the fan and a negative output voltage is removed and replaced with a current source. The current source also serves to shut down the power supply if the fan is not operating properly or is not installed. A shut down circuit remains to shut down the power supply when excessive temperature occurs, or when the current source detects that the fan is malfunctioning or not installed.

Abstract: A motor control unit for protecting a motor against overload, short circuit and ground fault currents. The unit monitors the currents in each phase of the motor to provide values representative of each phase current. The unit also includes a contactor for opening and closing each phase, wherein the unit controls the contactor based upon the values representative of the phase currents. The contactor is opened where the phase currents exceed limits which indicate that either an overload, short circuit or ground fault situation exists at the motor. A magnetic trip circuit breaker can also be provided to operate in cooperation with the unit to provide instantaneous trip protection for current levels which are relatively high in relation to those for which the contactor is rated.

Abstract: The motor relay includes thermal models representing the start and run conditions of a motor. The thermal models are implemented using measured current values and certain known operating parameters available from the manufacturer, specifically full load current, locked rotor thermal time and rated service factor. The thermal model information is compared with threshold thermal model values to determine when an overload condition has been reached.

Abstract: An electrical overcurrent circuit provides both digital based modeling and analog based modeling of the temperature of an electrical conductor to simulate the conductor temperature during all expected operating conditions including a condition when electrical power is unavailable to the electrical overcurrent circuitry. When electrical power is available to the circuitry, the conductor temperature is calculated from the sensed load currents to form the digital based model. During such a condition, the analog based model is forced to track the digital based model. Once the temperature of the electrical conductor exceeds its maximum safe operating temperature, the electrical overcurrent circuitry initiates a trip of the circuit breaker. Since the overcurrent circuitry is powered either by the sensed load currents or derived from the circuit breaker output, the circuit breaker trip will result in a loss of electrical power to the electrical overcurrent circuitry.

Abstract: A current limiting device to limit the maximum allowable electric current to be supplied to a motor in driving an electric vehicle. The current limiting device includes (a) a first thermal switch to prevent the power switching element of the motor from being abnormally overheated, (b) a second thermal switch to prevent the motor from being abnormally overheated, and (c) a brake switch. The three switches altogether and in association with a certain hysteresis band work to switch the limits of the electric current passing through the motor between two or more predetermined electric current values. Under normal operating conditions, the limit of the current is set at a high level which is associated with a hysteresis action, and when one of the thermal switches or the brake switch is actuated, the limit of the electric current is switched to a lower value which is still associated with a hysteresis action.

Abstract: A protective device for electric motors for protecting electric motors from high operational temperatures, has an element for determining an operational temperature of an electric motor and an element for automatically switching off of the electric motor when a predetermined limiting operational temperature is exceeded. The determining element is formed as electronic element for determining the operational temperature indirectly from an at least another operational parameter of the electric motor. The element for automatically switching off is formed as electronic element for automatically switching off of the electric motor.

Abstract: A synchronous machine is protected from closely spaced instances of excessive field current and an excessive volts/hertz ratio by a control system which models rotor and stator cooling to provide memory of recent periods of excessive heating. Maximum excitation limiting and volts/hertz ratio limiting modules in a microprocessor based automatic voltage regulator for the machine generate time delayed limit signals which override voltage feedback control when the respective parameters exceed threshold values. The limiters each increment a count when the associated threshold value is exceeded and generate the associated limit signal when a predetermined count is reached. The predetermined counts and the counting rates are selected such that the delay intervals are inversely proportional to the amount by which the threshold values are exceeded. The counts are decremented at a rate which models rotor and stator cooling when the respective parameters return below the threshold values.

Abstract: A method for the overload protection of devices which cannot endure continuous running on account of heat loss, to avoid a complex, cost-intensive direct coupling of the device to be protected to a temperature measuring element. The inside temperature within the housing of the device is merely measured and, on the basis of device-specific characteristics stored in an evaluation circuit, a permissible operating period assigned to the inside temperature is calculated. The permissible operating period is then used as a basis for the preset operating period cycle time.

Abstract: A starter protection circuit for a starting device of an internal combustion engine of a vehicle has a thermoswitch assignable to a starter, a relay which is activated by the thermoswitch when the thermoswitch is operative and interrupts a starter operation and a relay operating key which after assumption of a cold switching state of the thermoswitch can operate again the starter.

Abstract: A method and apparatus for remotely displaying information about heat in a motor having an associated motor-starting contactor with an overload relay system is provided. The apparatus includes a suitably programmed microprocessor which obtains a signal representative of current in the motor, squares the current and multiplies by time. This actual I.sup.2 t value is then used to calculate a signal representative of a relationship between the actual I.sup.2 t value and a target value at which the contacts of the motor-starting contactor will open due to an overload current situation. This relationship is preferably a percentage which is then displayed on either an LED bar type display or a digital display. The display may also include a "trip" indicator and a "reset allowed" indicator.

Abstract: Protection for an encased motor driven device is enhanced by utilizing additional sensors with associated resistance heaters to actuate the thermally responsive contacts of the internal line break. The sensors and heaters are powered from an auxiliary winding in the motor coils. When applied to a hermetic scroll compressor, the compressor can be protected against reverse rotation.

Abstract: An engine-driven power generating system comprising a bridge circuit section in which a low-frequency switching elements driven alternately by low-frequency drive signals, and high-frequency switching elements driven by high-frequency drive signals during the ON period of the low-frequency switching elements are connected in a bridge network, and an inverter circuit section having a drive signal supply circuit for supplying low-frequency and high-frequency drive signals are each supplied to the low-frequency and high-frequency switching elements that form a pair; the a-c voltage generated by an engine-driven a-c generator is converted into d-c voltage that is in turn converted into a predetermined level of low-frequency a-c voltage; characterized in that an emergency relay circuit device for protecting the engine-driven power generating system against abnormal operating condition.

Abstract: A motor control method for determining the temperature of a motor wherein the operation and nonoperation times of the motor are monitored, an estimated temperature is determined as a function of the monitored times and predetermined temperature rise and temperature fall characteristics of the motor, and the motor is stopped and/or an alaram signal is generated if the estimated temperature exceeds a predetermined temperature.

Abstract: A stepping motor unit includes a stepping motor of the type wherein the interior of the stepping motor is filled with an oil, a detector for detecting the temperature of the oil in the stepping motor, a device for varying an upper limiting value of the rotational speed of the stepping motor and an upper limiting value of the rotational acceleration of the stepping motor in view of a current viscous condition of the oil based on the temperature detected by the temperature detector, and a driver for driving the stepping motor at a rotational speed and a rotational acceleration which fall in ranges, respectively, not exceeding the upper limiting values. The stepping motor unit thus constructed has rapid and accurate response characteristics and is capable of operating reliably without falling out of step even when the environmental temperature varies in a very wide range. A rotary control valve incorporating such stepping motor unit is also disclosed.

Abstract: A method for continuously determining the consumed insulation life of an electrical winding in a rotating machine is described incorporating the steps of selecting constants based on the class of insulation material and rotating machine power rating, measuring the temperature of the insulation over time, determining the consumed life of the insulation for consecutive periods of time and summing the consumed life. The invention overcomes the problem of determining consumed life of electrical insulation.

Abstract: Method of controlling at least one electric motor on an offset printing machine by inputting a set point for the rotational speed, which comprises forming a set point for the rotational speed by means of a device for controlling the electric motor, and reducing the value of the set point as a function of a measured line voltage when the line voltage is inadequate.

Abstract: Thermal overload of a motor is avoided by measuring temperature and, when a limit temperature is exceeded, reducing the phase "window" within each power cycle during which the motor is energized. The limit temperature is sensed by a temperature sensor which is warmed either by heat conduction through a cooling body or by an air stream from the motor. The overload protection apparatus requires no measuring resistance in the load circuit.

Abstract: An apparatus for starting and controlling a motor. The apparatus includes means for monitoring the load current values in each phase of a motor. These means can include an apparatus such as a current transformer. The apparatus utilizes a circuit for modeling a motor and estimating the temperatures of the motor's windings and housing. THe circuit preferably is defined by a programmed microprocessor. The estimated temperatures are based on the load current values and time. These estimated temperatures are then compared to allowable limits and, based on the comparison, the motor is either stopped or allowed to run.

Abstract: A highly efficient over current circuit breaker for an electric system is provided with a timer which is adjustable and can be set to produce a first control signal a predetermined time after the electric system is turned on, and a load detector in association with an over current control device which produces a second control signal when the load applied to the electric system exceeds a predetermined level. The first control signal and second control signal jointly activate an amplifier to produce a third control signal which activates relays to cause a magnetic switch to open, or "trip", whereby the electric system is turned off. The timer allows an electric surge to occur in the electric system without causing the magnetic switch to trip during the period of starting the electric system. The circuit breaker is particularly useful in systems having induction motors in which starting current surges are common.

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 device and method for detecting the coil temperature of a direct-current motor by determining the resistance of at least one coil of the motor. The method includes measuring a parameter of the at least one coil while the motor is running. The measurement is made at a time interval in which the coil is without current. The measuring device includes a commutation circuit of the motor which generates a time interval used for measuring the current.

Abstract: An electric motor having at least two salient stator poles equipped with windings, covering members inserted into gaps between the poles, and a protector switch associated with the field windings. The protector switch is mounted at a predetermined position on one of the covering members using a clamping element which is configured as an elongated component and which is provided with a receptacle for the housing of the protector switch and a holder for leads extending from the switch. The clamping member snaps into a recess in the cover member extending in the direction of the motor axis. The clamping element orients the protector switch so as to avoid contact chatter due to vibration of the motor.

Abstract: A device for monitoring the temperature in a DC shunt-wound motor for driving rotary printing machines includes a temperature measuring sensor formed of a DC shunt winding of the DC shunt wound motor.

Abstract: A control system for a gas turbine engine guards the engine against destructive overspeed resulting from failure of electronic components in the system due to overheating. A main electronic (preferably digital) controller is normally in control of fuel flow to the engine by means of a flow metering unit. In addition, an electronic overspeed limiter guards against overspeed at normal system temperatures, should the main controller fail, by overriding the action of the main controller on the flow metering unit. A failsafe unit is responsive to the temperature of the control system, and comprises components rated at a substantially higher peak operating temperature than the components used in the other units. The failsafe unit acts as an ultra-reliable switch operative to depower the main controller, and, optionally, the overspeed limiter, when the temperature of the control system exceeds a predetermined value above which components in the two latter units are likely to fail.

Abstract: A bidirectional motor has two electromagnetic contactors, one for forward, the other for reverse operation. Thermal protection is provided by a thermal image generator and a thermal protection unit in each contactor operating in tandem via a bidirectional line of communication keeping the thermal images in parallelism by one active contactor "talking" to the inactive contactor, the "listener".

Abstract: A motor-driven power steering system for a vehicle capable of preventing a motor-related element such as a motor itself, power elements for controlling power supply to the motor or the like from being damage due to an abnormal temperature rise or overheating thereof, thereby substantially avoiding or reducing resultant unsureness or instability in the operator's steering feeling upon change in steering mode as well as improving safety in steering operation. The motor is operatively connected with a steering rack and energizable by a power source for power assisting the steering motion caused by the operator through a steering wheel. A temperature sensor detects the temperature of the motor-related element. An electromagnetic switching clutch is interposed between the motor and the steering rack for selectively establishing and interrupting the transmission of power assisting force from the motor to the steering rack in accordance with the travelling speed of the vehicle.

Abstract: An electromagnetic assembly including an electromagnetic coil wound on a core of ferromagnetically conductive material. A temperature protection circuit includes a fuse which breaks when the electromagnetic assembly becomes overheated. The fuse is thermally coupled to pole pieces of the assembly and is in electrical circuit with the coil.

Abstract: A device for mounting a thermal overload protector to the motor of a hermetic refrigeration compressor. The overload protector is temperature responsive and is operative to protectively interrupt the current to the motor when the stator windings, rotor, or other heat source in the compressor overheats due to a compressor overload. The protector's mounting device is a plastic receptacle having a shield connected by an integral hinge. The hinge not only facilitates manufacturing the receptacle as a unitary part by an injection molding process, but also enables the shield to be opened for inserting the overload protector into the receptacle. The overload protector is held firmly in place by a U-shaped bracket integrally disposed inside the receptacle. A U-shaped groove runs along the inner edge of the bracket and is designed to slidingly engage protectors of various shapes. The receptacle includes an opening on one side of the protector opposite the heat retaining shield.

Abstract: A device is provided for digitally determining and safeguarding a thermal image including a processor connected to at least one sensor able to form a digital image of the thermal state of an apparatus, a random access memory containing the thermal image formed by the processor and a safeguard for storing, should there be a voltage cut, the instantaneous thermal image. The safeguard includes a programmable digital counter fed by a capacity curing power-cuts and equipped with a clock which modifies its counting state for the duration of the absence of voltage. The processor reads the state of the counter after restoration of the voltage.

Abstract: A PTC starter that is electrically connected to an asynchronous motor by pins that extend through holes into the starter housing, which includes an open top, generally box shaped base portion and a cover having a downwardly opening recess mountable on the base portion. Support structure is provided in the base portion for loosely retaining a disc shaped PTC resistor and a pair of contact members on opposite sides of the resistor in a loose stacked relationship with the resistor, the support structure including a base portion receptacle for loosely retaining an electrical terminal bushing portion adjacent to a contact member. The cover in having its recessed portion moved downwardly along the contact members and resistor result in the contact members being resilient retained in electrical engagement with the resistor electrode surfaces, and at least two terminals extending upwardly through the cover. Advantageously the housing mounts a thermal protective switch for the motor.

Abstract: A thermally released switching mechanism which in a simple fashion and at a precisely defined switching point clearly interrupts the current to the motor when a preset, highest admissible temperature is exceeded, at least until the actual temperature has once against fallen below the highest admissible temperature. The thermally released switching mechanism is comprised of a lever element made of a memory element which, upon exceeding the highest permissible temperature set value, lifts the brush from a commutator or a slipring. This mechanism preferrably employs a memory element with a two-way effect. This thermal switching mechanism is suitable both for commutator motors with hammer or tubular brush holder systems as well as for slipring motors.

Abstract: A brushless DC fan with a winding supply circuit having an internal voltage regulator can afford current limiting and thermal protection and provide various desired fan speeds without alteration of the basic fan circuit, the windings, or other manufacturing items. A voltage setting circuit element can set fan speed externally and can be used to establish various fan speeds. An internal voltage establishing circuit element sets the maximum speed. The regulator replaces the fan's protective thermistor to shut down the voltage to the windings when locked rotor occurs. Bringing out a lead for the purpose of connecting a speed controlling resistor, thermistor, or active programming means to the internal circuitry enables the fan's end user to alter operation as needed.

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 process for controlling the speed of an electric motor. A reference value of motor temperature is provided and directed to a summing junction. The actual temperature of the motor is sensed and also directed to the summing junction. The two values are summed and employed as a reference of motor current. This reference is directed to a second summing junction while the value of actual motor current is sensed. The actual value is also directed to the second junction. These last two values are summed at the second junction to provide a reference for adjusting motor speed.

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.