Abstract: A soft start electromagnetic coupling has a driven member and a driving member that are coupled together in response to a magnetic flux produced by a direct current flow through a winding on the clutch. When the members are coupled by an electromagnetic flux, they may slip relative to reach other during starting, when the load on the coupling changes or when the accessory driven by the coupling freezes or becomes jammed. Relative slippage of the members produces an alternating current component in the direct current flow that is detected to indicate the slippage. The presence of an alternating current component can be sensed through a rectifier or frequency filter. Preferably, the presence of a persistent alternating current component causes a switch to open, interrupting the flow of direct current to the coupling.

Abstract: A motor driving apparatus includes a motor, a signal generating device for generating a Pulse Width Modulation binary signal, a control device for applying a current to the motor, a current detecting device for detecting the current applied to the motor, and a current blocking device for blocking the current applied to the motor for a predetermined time when the current applied to the motor exceeds a predetermined value. The current blocking device is synchronized at an alternative cycle of the binary signal, whereby it is possible to limit the current applied to the motor during the overload of the motor.

Abstract: The present invention comprises a relay control circuit that provides highly efficient and reliable control for devices that perform in demanding applications such as space. Multiple levels of redundant function control are provided by redundant actuators that perform mechanical operations. Each actuator is driven by redundant motors for increased reliability. Motor current sensing is provided to determine arrival of the actuator at mechanical stops, which are located at the full deploy position. Limit switches also sense when the actuators are in the full deploy position. In addition, multiple control signal so are required to initiate certain critical operations. Critical operations also are performed redundantly for increased reliability.

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: The motor-driven power steering unit according to the first aspect of the present invention is able to decrease the amount of current being applied to the motor if the steering force exceeds a predetermined level. The motor-driven power steering unit according to the second aspect of the present invention is able to decrease the amount of current being applied to the motor when the steering speed is less than a predetermined level.

Abstract: A dc commutator motor can be switched off when the motor rotor is short-circuited by the rotor's coming to a halt, by an operating switch (10). The switch is provided in the line connecting the brushes to a radio suppression network in a compact and simple design. The switch is operated by an ac voltage induced when the motor is running, with a frequency corresponding to the motor speed. A sensing winding connected to the operating switch for inducing the operating ac voltage is wound preferably around a radio interference suppression choke of the radio suppression network.

Abstract: A motor control device controls a motor driving mechanism which drives a motor according to a motor drive signal for providing a normal drive signal and a locked condition signal. When the motor becomes overloaded while being driven by the motor driving mechanism according to the motor drive signal, the motor driving mechanism is controlled by controlling circuitry which inhibits the motor drive signal from being supplied to the motor driving mechanism. The controlling circuitry, while the motor is in the overloaded state, controls the motor driving mechanism so that power is supplied intermittently to the motor, or so that the supply of power for the regular and reverse rotation is given alternately. The controlling circuitry, when the load of the motor becomes normal, allows driving of the motor according to the motor drive signal.

Abstract: A method and apparatus prevents the overheating of a line feed motor used in a printer. First and second timers are respectively provided to measure first and second time intervals. The second time interval includes a cessation period in which the line feed motor is not driven to allow for heat dissipation of the line feed motor. At the end of the first time interval, a determination is made as to whether the number of line feed pulses during the first time interval exceeds a predetermined limit. If the number of line feed pulses does not exceed the predetermined limit, the first time is reactivated. If the number of line feed pulses does exceed the predetermined limit, then the second timer is activated to allow for heat dissipation of the line feed motor.

Abstract: In an active shaft ground system for maintaining a rotating shaft (4) of a machine substantially at ground potential, which system includes a circuit coupled to the shaft (4) for monitoring the voltage on the shaft (4) relative to ground and a brush (6) coupled to the circuit and contacting the shaft (4) for conducting to the shaft (4) a compensating current having an amplitude and polarity adjusted for maintaining the shaft voltage substantially at ground potential, there is provided shaft condition detection circuitry (18,20,24,26,28,34,36) coupled to the circuit for monitoring the voltage on the shaft (4) relative to ground and the current flowing between the brush (6) and the shaft (4) and for producing a fault indication when the voltage on the shaft (4) relative to ground is outside of a selected range at the same time that the current flowing through the brush (6) is substantially equal to zero.

Abstract: A microwave oven and a refrigerator are combined into a single cabinet housing a shared power supply with an electrical supply disconnect for the magnetron of the oven during a start-up power demand by the compressor of the refrigerator and for a period of time depending upon a rating of the compressor.

Abstract: An electrical circuit for providing electrical energy to an electric motor which operates a liquid pump. The motor and the pump are adapted to be submerged in the liquid which is pumped by the pump. The circuit disclosed herein senses the phase angle between the current and the voltage applied to the electric motor. When the phase angle indicates that the motor is operating without a load, the circuit deenergizes the electric motor. Thus, the motor and the liquid pump are protected against damage. Recognizing that harmonics may exist in the current flow through the motor, the circuit provides for obtaining a filtered signal proportional to the fundamental frequency of the current flowing through the motor. Thus, an accurate measurement of the loading of a motor is obtained. The circuitry of this invention also provides an accurate method of compensation for applied line voltage variations, so that a change in the applied line voltage does not produce a false indication that the motor loading has changed.

Abstract: A thermal overload detector and interrupter has a current transformer for monitoring load current and providing a current value signal, a microprocessor for calculating values related to load current and the thermal characteristics of a load, and an interrupter for selectively conducting and interrupting load current. The microprocessor computes a square current value from the current value signal and multiplies the square current value by a predetermined constant to obtain a multiplied square current value. The predetermined constant is related to the heat transfer characteristics of the load. A present running sum is computed in the microprocessor by adding the multiplied square current value to a past test value. The microprocessor then computes a proportionate present running sum by multiplying the present running sum by the predetermined constant. A present test value is computed by subtracting the proportionate present running sum from the present running sum.

Abstract: A method and apparatus for detecting rotor faults in an induction motor. A flux sensor generates a flux signal corresponding to the magnetic flux at a predefined flux detection point external to the motor. A current sensor generates a current signal proportional to the current drawn by said motor. A time series of data points is stored, representing the values of the flux signal and the current signal over a period of time. The time series are transformed by FFT into a set of flux spectra and into a set of current spectra. Then the line frequency of the motor's power supply is determined by finding the maximum of the current spectra. Similarly, the slip frequency of the motor is determined by finding the maximum of the flux spectra in a predefined spectral range (e.g., below 2 Hz). The analysis of the rotor is then performed by comparing the amplitude of the current spectra, at a set of rotor fault harmonic frequencies, with specified fault threshold criteria.

Abstract: A magnetically latching switch assembly adapted for use with a motor including first and second serially connected coils wound around a frame to generate oppositely directed magnetic flux through the frame. The coils are arranged so that for the normal run current of the motor, the net magnetic flux is sufficient to magnetically latch the switch against the restoring force of a spring. When the motor is stalled, the increased current is sensed and a portion of the current is diverted from one of the coils to reduce the net magnetic flux and terminate the latching effect. Current sensing and diverting is accomplished by a diode connected across the one coil.

Abstract: Overload protection for the series resistance of an electric motor in which a voltage drop across the electric motor is monitored. During the occurrence of a reduced voltage drop, for example, as a result of a blocking of the motor or of a fan driven by the electric motor, the series resistance is short-circuited by a relay so that the blocking can be overcome by an increased driving torque of the electric motor or a fuse in the load current input line to the motor responds. As a result thereof, an effective overload protection is created which is of simple construction, involves no additional wiring expenditure and requires few additional components and which also permits to dimension the series resistance for normal operating currents and to be able to dispense with a thermal monitoring.

Abstract: A power switching circuit for switching power repetitively to a load at a relatively low frequency employs a power switching device which is driven across an isolating transformer interface. The drive signals are high frequency pulse signals which are modulated with the low frequency switching information, the modulations being detected in the secondary circuit of the transformer. Such an arrangement affords isolated driving with fast switching edges and requires only a small transformer. Power for the detection circuit is derived by rectification of the high frequency signals induced in the transformer secondary.

Abstract: A technique for detecting the occurrence of stall currents in a D.C. motor control circuit and inhibiting the application of drive currents to the motor by monitoring the current flow through the motor and responding to stall currents that are continuous for a predetermined period of time.

Abstract: The safety circuit of the present invention is connected to a drive control circuit for applying driving signals to a plurality of switching devices connected to respective stator coils of the brushless D.C. motor at a predetermined timing, and sequentially supplying a driving current to each phase of the stator cells. The safety circuit is adapted to simultaneously detect the driving signals and generate a cut-off signal for cutting off the driving current supplied to each of the stator coils in the event that the driving signals are simultaneously applied to the switching devices in controlling a driving operation of the brushless D.C. motor.

Abstract: A detection device for contact fusion in an electromagnetic contactor in which an electric motor is connected by way of main contact of an electromagnetic contactor on the secondary side of a breaker equipped with electronic tripping device has a detection circuit for the voltage applied to the electromagnetic contactor coil connected in series with a pushbutton switch and a detection circuit for the voltage applied to the electric motor; a relay coil of a relay for detecting the contact fusion is connected to the tripping coil of the breaker and an ON-OFF element for supplying or interrupting the supply of an electrical current to the coil and a control circuit for the ON-OFF element are connected to the detection circuit for the voltage of the electrical motor both of the detection circuits are coupled with each other by a photocoupler, whereby the ON-OFF element is turned ON when the pushbutton switch is turned OFF in the case of the fusion of the main contacts, thereby exciting the relay coil to turn the

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 safety circuit for a window lift driven by an electric motor is described which causes a reversal in the direction of rotation of the drive motor when the window pane impinges on an impedance in its upward motion. The reversal criterion used is the motor current surge familiar to the state of the art. The circuit of the invention is characterized in that upon actuation of the "close" window key, the drive motor first rotates briefly in the direction of opening and thereby displaces the window pane downwardly, whereupon it is automatically reversed and only then does the pane motion toward the closed position begin. Consequently, the motor start-up peak current decays in that range of displacement of the window pane which is below its initial position, whereby an increase in current (di/dt) after resuming the initial position of the window pane at once causes motor reversal.

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 electrical short-circuit monitoring arrangement for a three-phase motor, including its supply lines, whose speed is controlled by a constant-current d.c.-link converter. The harmonic ripple voltage superimposed on the motor voltage generated as a consequence of the commutation by the constant-current d.c.-link converter at the output of the converter is determined, filtered, and supplied to a phase-monitoring unit, which when dropping below a selected amplitude variable of the harmonic voltage of at least one phase, triggers the switching module whose switching mechanism activates a disconnect switch to interrupt the motor circuit upon occurrence of a switchoff signal.

Abstract: A circuit arrangement for monitoring ground faults to a normally ungrounded coil of a motor, the circuit arrangement including;a source of a low-level d.c. voltage, the source having first and second output terminals between which the d.c. voltage is established and a conductive connection being established between the first output terminal and the motor coil;a current responsive unit connected between a point at ground potential relative to the motor coil and the second output terminal of the source for producing an output signal proportional to the amplitude of current flow between the second terminal and ground; anda motor control unit connected for preventing operation of the motor when the output signal from the current responsive means reaches a selected value.

Abstract: A protective circuit for a manually controllable adjusting device for motor vehicle seats, which is driven by an electric motor, has a current sensor (11) with an output voltage which corresponds to the sum of all instantaneous currents flowing in the motor electrical circuit of the adjusting device. Furthermore, a threshold switch stage (14, 16, 24, 25, 26) which responds to a predetermined value of the output sensor (11) and a switch (12) which lies in the electrical circuit of the electric motor are provided. This switch (12) can be switched from its closed condition into its opened condition by the threshold switch stage when a threshold value is exceeded.

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 protective circuit arrangement of a motor control for the starting and operation of a motor of a press with a power stage, a current-regulating element and a rotational speed regulating element. Comparator stages are connected to the inputs of the regulating elements for forming the guide magnitudes from the actual current value and the desired current value as well as from the actual rotational speed value and the desired rotational speed value. For suppressing the disconnect signal during the starting phase of the motor, the circuit additionally includes a rotational speed comparator stage, a desired current value memory and a current comparator stage. The desired current value, which stored after the starting phase in the desired current value memory, is compared with the current value in the current comparator stage to produce a motor current interrupt signal in case of an overload current that might lead to a press damage.

Abstract: A motor controller with means responsive to a motor condition for preventing termination of power to the motor in response to fault conditions when these fault conditions occur during start-up of the motor.

Abstract: Electrical circuit configurations are described for the operation of an electrically powered actuator in an emergency to drive the actuator to a predetermined position. In particular the actuator is connected to apply friction brakes of a railway vehicle. The configurations have in common are emergency power circuit connected between an emergency power source and the actuator, means for breaking the power circuit when the actuator reaches the emergency position and latching means to prevent run-back. Preferably and in order to minimize size and weight the emergency power source is of limited capacity, sufficient for, say, two such emergency applications and is recharged from a normal power supply; the recharging circuit being interlocked with the latching means such that the actuator may not be released from the emergency position unless the power source has sufficient charge for at least one further emergency operation.

Abstract: A H-switch circuit is disclosed for rotationally driving a DC motor in a forward or reverse direction. The H-switch circuit comprises overcurrent-detecting circuits for four output transistors, which are respectively provided in order to detect the output transistor having an overcurrent, a circuit for generating an output signal upon detecting an overcurrent an integrating circuit controlled to be in a charge or discharge state according to the output signal representative of an overcurrent condition, and a circuit for turning off the output transistors when the integrating circuit is in the charge state and setting the integrating circuit to a discharge state. The charge and discharge operations of the integrating circuit are intermittently repeated until the overcurrent condition of the output transistor ends.

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 electric motor driven power steering system is provided. The motor is prevented from operating at low torque command levels. After a first predetermined level of command torque is reached, the motor is controlled to generate torque at a predetermined rate less than the torque actually commanded by the vehicle driver. After a second predetermined level of commanded torque is reached, the motor is controlled to generate torque in accordance with the level of torque command. Thus, the phenomenon known as "hunting" and instability of the system at low torque levels are virtually eliminated. The system operates smoothly over its full range of operation and is not affected by rough road surface conditions.

Abstract: DC power control system for use in an electric vehicular system has DC power supply and power conductors. A meter relay in a control unit enclosure displayably measures the DC current in the conductors and simultaneously establishes an overcurrent limit for tripping out the conductors when the limit is exceeded. Meter calibration and tripping function are testable by a test switch for substituting an adjustable DC test source in place of a conductor meter shunt to the meter relay. Application of DC to shorted power conductors is prevented by preliminary low power DC isolated AC relaying across the conductors. The test switch substitutes a low resistance for the power conductors to also test the AC tripping action. If the power conductors are already energized from a remote power supply, the local power supply is prevented from access by DC responsive relaying during a preliminary time period. After a problem is detected, the control system locks out so as to demand operator attention if the problem persists.

Abstract: A circuit for detecting the failure of a step motor to respond to energization commands, which takes advantage of the time constant decrease of an energized phase which occurs due to stalling of the motor. A predetermined current level I in the energized phase is reached in a time interval TI which is shorter than a time interval TO necessary to reach the same current level when there is a response of the motor. The circuit comprises a timer having a predetermined period between TI and TO which activates a bistable circuit indicative of a failure to respond if the current level I is reached in a time shorter than the required time period.

Abstract: The traction motors of a locomotive are voltage limited to a variable extent to permit continued motor operation following the occurrence of moisture induced ground faulting. The heat generated by the continued motor operation dries the moisture which induced the ground faulting, and the voltage limit is progressively increased toward a normal level for each specified period of motor operation with no ground faulting.

Abstract: An A.C. overload current sensing, remote power controller of minimum size and weight and integral construction. Current rate sensing wound toroids are used that are small enough to fit around the line terminal studs without having to enlarge the prior insulator space available therein. The electronic overload current detecting and tripping control circuit is replaced by a pair of modules, detector and control modules, having improved performance and a shape and size such that they fit within the relay housing alongside its operating magnet. The detector module has integrator means for converting current rate of change signals into current magnitude indicative signals thereby enabling use therewith of rate sensing wound toroids of about one-tenth the size of equivalent current transformer wound toroids.

Abstract: When a load current on a motor was to be monitored, all the digital values of the load current at the model operation were conveniently memorized in a memory to be compared with the load current value of the actual operation. The capacity of the memory therefore became enormous, presenting a problem. This invention enables to memorize a load current of a motor at the model operation in terms of the dimensional difference from a reference value and of duration of time. Thanks to such an arrangement, the volume of stored data can be reduced to minimize the capacity of the memory, thereby facilitating the comparison process of data at the time of actual operation.

Abstract: The analog electronic trip device comprises a time-lag tripping circuit formed by a non-linear function generator likely to elaborate by approximation the tripping characteristic of the circuit breaker.The device includes an integrating amplifier comprising a negative-feedback capacitor C and two inputs in phase opposition. One of the inputs is submitted to two threshold voltages V.sub.R1, V.sub.R2 determining the mode of long-time delay or short-time delay operation of the trip device. The second threshold voltage V.sub.R2 is set by a resistive switch which determines the short delay tripping threshold.

Abstract: The magnitudes of currents in the armature and field windings of a separately excited d-c motor are compared, and a fault signal is produced in response to the field current magnitude either rising above a first reference level (which varies as a first predetermined function of the armature current magnitude) or falling below a second reference level (which varies as another predetermined function of the latter magnitude).

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 system senses alternating current in a conductor, such as a main line supplying electrical power to a home, and responds to the sensed current as by providing a warning signal when the sensed current exceeds or is less than a preset value for a predetermined short period of time. The current sensor itself is a simple coil of wire, either with an air core or a partial ferromagnetic core, which can be easily operatively associated with the current carrying conductor without the need for disconnecting the conductor from its terminals and which when installed does not present the hazards associated with current transformers.

Abstract: An overload detection circuit protects a motor against currents above rated current that persist for certain exposure times. The allowable exposure times are inversely related to the degree of overload current. The circuit has two overload current sensors with two respective overload thresholds. These are both connected to a pulse generating circuit and the pulse rate is accelerated when the second overload threshold is reached. The pulse generating circuit couples pulses to a pair of cascaded counters which generate a fault signal when a predetermined count is reached. The pulse generating circuit includes an integrator with a capacitor that must be discharged, before another pulse can be generated. The pulse generating circuit includes a comparator which operates a switch to discharge the capacitor shortly before coupling each pulse to the counters, to prevent a delay that would otherwise occur between signals from the integrator circuit.

Abstract: An overcurrent protection circuit for inductive loads such as motors is provided. A source voltage is input to a divider circuit including semiconductor switching devices. The inductive load is also connected to the voltage source through the divider circuit. A voltage output from the divider circuit which is proportional to the current through the inductive load is input to a comparator circuit. Another input to the comparator circuit comprises a reference voltage selected to correspond to the maximum desired current through the inductive load. If the comparator circuit senses that the current through the inductive load is greater than the predetermined maximum current, it provides an output to a pulse generator device. The output from the pulse generator device is input to a switching circuit which can cut off the voltage source supply to the inductive load.

Abstract: A method of and apparatus for protecting three phase electrical equipment where a signal is derived for each phase representing current in each phase, and the three signals combined to form an analog composite signal. The analog composite signal is converted to digital form. One of the analog signals is used to relate the values of the digital signals to respective phases. The largest value is used to determine heating in the equipent and from the heating the temperature of the equipment is derived. The temperature is compared to critical temperature levels and when a critical level is exceeded, the supply of power to the equipment is interrupted. The digital signals representing the current peaks in each phase are used to determine phase loss and phase unbalance, and the power supply is interrupted when there is a phase loss or when the unbalance exceeds a predetermined critical level.

Abstract: An apparatus for protecting machinery driven by electric motors from operating during over-load and light-load conditions, comprising: a current transformer operatively associated with an electrical supply line for the induction motor; a current-voltage transforming circuit for generating a control signal having a magnitude proportional to current flowing in the supply line; an upper limitation magnitude comparator for generating an over-load signal output whenever the magnitude of the control signal exceeds a predetermined upper safety value; a lower limitation magnitude comparator for generating a light-load signal output whenever the magnitude of the control signal is less than a predetermined lower safety level; an inhibitable protection timer for producing a fault persistence output signal whenever one of the over-load and light-load signal outputs is generated for a period of time longer than a predetermined protection time; a steady state timer for inhibiting an enable output signal for a predetermined

Abstract: An overcurrent circuit interrupts energization of the electric motor of a motor vehicle electric power steering system whenever the motor current exceeds an overcurrent limit, thereby defining an overcurrent duty cycle. When the overcurrent duty cycle reaches a value indicative of motor stalling, the overcurrent limit is reduced to protect the motor and its drive circuitry during prolonged motor stalling.

Abstract: A circuit breaker with a high linearity is provided which detects a current in a main circuit in a low current region by means of a current transformer, while the current in a high current region is detected by a current detector using a Hall element.

Abstract: A system for protecting an electrical component, drawing current from a power source, utilizes a sensor providing an output signal proportional to the square of the load component current. The squared-current signal, when greater than a squared-normal-current signal, is integrated and compared to a current squared-time value. A system output is enabled if the load component instantaneous i.sup.2 t value is greater than the current squared-time value set at the comparator, to remove the current flow to the protected component.

Abstract: A motor controller receives a signal proportional to motor current, integrates that signal during the high currents associated with starting, and holds a level during normal operation at speed within a maximum current limit. When an overload causes the motor to trip and there is a loss of power to the controller, a memory holds the level for a predetermined time to prevent an immediate restart of the motor.