Abstract: Method of cooling computer equipment that includes pumping coolant into a passageway leading to computer equipment and distributing the coolant from the passageway to heat sinks. The method also includes iteratively adjusting a rate of cooling of electronic devices by the coolant directly or indirectly in dependence upon heat generated by the electronic devices. The method also includes monitoring the respective temperatures of the electronic devices or heat conductive material in thermal contact therewith. The method also includes iteratively calculating the average of the values that said temperatures have at a given time. The method also includes iteratively calculating a spread value indicative of the spread of said values and iteratively adjusting the rate of cooling of the electronic devices by the coolant in dependence upon the ratio of said spread value and a difference between said average and a predetermined maximum acceptable temperature.

Abstract: A docking device includes a bus interface and a network interface controller. The bus interface is configured to be connected to a host device. The network interface controller is coupled to the bus interface and configured to receive a host-based MAC address of the host device and load the host-based MAC address for a network communication, if the host device is connected to the docking device via the bus interface. The host-based MAC address is stored in a table with a vendor specific format structure in a BIOS of the host device.

Abstract: A surgical cutting and fastening instrument comprises an end effector that has a shaft coupled thereto that is coupled to a robotic system. A tool mounting portion includes an electric, DC motor connected to a drive train in the shaft for powering the drive train. A power pack that comprises at least one charge-accumulating device connected to the DC motor for powering the DC motor is provided.

Abstract: Systems and methods for determining the existence of a pump-off condition in an ESP system and controlling the motor to prevent fluid pound that would otherwise result from the pump-off condition. The current drawn by the ESP motor during a power stroke is monitored and the instantaneous force generated by the motor is determined from the instantaneous current. Pump-off conditions may be indicated by sudden, large decreases in the generated force, smaller decreases in force that occur over a longer period, or forces below those seen during a dwell time. In response to detecting a pump-off condition, the motor may be stepped through the rest of the stroke, temporarily halted and re-initialized, thereby preventing potentially damaging fluid pound that would otherwise result from the pump-off condition.

Abstract: A system and method are disclosed for controlling the opening and closing of a closure panel for a vehicle. The system includes a power actuator having a motor for opening and closing the closure panel. A lift-assist member cooperates with the power actuator and is operated by a controller that controls the operation of the power actuator. A circuit monitors current draw of the motor and signals the controller when the current required for opening the closure panel exceeds a predetermined level to prevent operation of the power actuator. The position of the closure member may be monitored by an encoder, or angle sensor, associated with the motor to detect whether the closure member is falling and actuate a system that prevents rapid movement of the closure member.

Abstract: An apparatus for controlling a boost converter is provided with: an operating device provided with a proportional element, an integral element and a derivative element, the derivative element being configured as a bandpass filter, the operating device calculating a PID controlled variable; a controlling device for controlling the output voltage of the boost converter on the basis of the calculated PID controlled variable; a judging device for judging whether or not loss suppression on the direct current power supply is to be prioritized; and a switching device for switching an operation mode of the operating device from a variation suppression mode to a loss suppression mode if it is judged that the loss suppression is to be prioritized. In the loss suppression mode, a cutoff frequency of the bandpass filter is corrected to a lower frequency side at a lower rotational speed of the three-phase alternating current motor.

Abstract: A distributed motor drive system includes a power management module and multiple inverter modules integrated with the motors and located on a machine or process remote from the power management module. The power management module distributes DC voltage and command signals to each of the inverters, where the DC voltage is distributed between modules via a DC link cable. The integrated inverters execute switching routines to convert the DC voltage to an AC voltage suitable for controlling the motor. Each of the power management module and the inverters includes a portion of the DC bus. The current on the DC link cable is monitored and general bus utilization as well as overload conditions are reported.

Abstract: A compressor apparatus includes a power source (26), a shell (12; 42), an electric motor (28; 52; 100; 200) having motor windings, and a control assembly (106; 206). The electric motor (28; 52; 100; 200) is located within the shell (12; 42). The control assembly a control assembly (106; 206) provides power to the motor windings from the power source (26) in two modes. A first mode provides power to the motor windings to generate heat without producing force output with the motor (28; 52; 100; 200). A second mode provides power to the motor windings to produce force output with the motor (28; 52; 100; 200). The control assembly (106; 206) activates the first mode for a selected time period prior to activation of the second mode in order to drive out a fluid (36) to reduce a risk of a flooded compressor start.

Abstract: Automated shade systems comprise motorized window coverings, sensors, and controllers that use algorithms to control operation of the automated shade control system. These algorithms may include information such as: 3-D models of a building and surrounding structures, shadow information, reflectance information, lighting and radiation information, ASHRAE clear sky algorithms, log information related to manual overrides, occupant preference information, motion information, real-time sky conditions, solar radiation on a building, a total foot-candle load on a structure, brightness overrides, actual and/or calculated BTU load, time-of-year information, and microclimate analysis.

Abstract: A method of controlling a motor operating a pumping apparatus of a fluid-pumping application. The pumping apparatus includes a pump having an inlet to receive a fluid and an outlet to exhaust the fluid, and the motor coupled to the pump to operate the pump. The method includes the acts of controlling the motor to operate the pump and monitoring the operation of the pump. The monitoring act includes monitoring a power of the motor, and determining whether the monitored power indicates an undesired flow of fluid through the pump. The method further includes the act of controlling the motor to cease operation of the pump when the determination indicates an undesired flow of fluid through the pump and zero or more other conditions exist.

Abstract: An electrical switching apparatus is for another apparatus including a number of insulators, a number of temperature sensors operatively associated with the number of insulators, and a number of conductors operatively associated with the number of insulators. The electrical switching apparatus includes a number of separable contacts, an operating mechanism structured to open and close the separable contacts, a number of sensors structured to sense a number of currents flowing through the separable contacts and through the conductors, a processor structured to input the sensed currents from the sensors, and an output. The processor calculates at least one of: (a) a thermal age of the other apparatus from a number of sensed temperatures from the temperature sensors, and (b) the thermal age of the other apparatus from the sensed currents. The output includes the thermal age of the other apparatus.

Abstract: Automated shade systems comprise motorized window coverings, sensors, and controllers that use algorithms to control operation of the automated shade control system. These algorithms may include information such as: 3-D models of a building and surrounding structures, shadow information, reflectance information, lighting and radiation information, ASHRAE clear sky algorithms, log information related to manual overrides, occupant preference information, motion information, real-time sky conditions, solar radiation on a building, a total foot-candle load on a structure, brightness overrides, actual and/or calculated BTU load, time-of-year information, and microclimate analysis.

Abstract: Method and arrangement for connecting an AC electric motor (M1, M2, . . . MN) to an AC electricity network (L) in a system which comprises a frequency converter (FC), with which the motor is started, and contactors (S11, S12, S21, S22, SN1, SN2), in which method the supply source is changed by means of the contactors from the frequency converter to a direct network supply, in which method the frequency converter is stopped before changing the supply source, and in which method in connection with changing the supply source the control of the contactors is started before stopping the frequency converter.

Abstract: A window covering driving device includes a motor and a control circuit, the control circuit is provided with a microprocessor, a control wire, a control signal input terminal, and a switching circuit and the motor is connected to a drive power supply via the switching circuit. The switching circuit is connected to the microprocessor and the control signal input terminal is connected to the microprocessor via the control wire. A safety position limiting wire is also included with one end of the safety position limiting wire being connected to the microprocessor and the other end is connected to a safety position limiting signal control terminal. The safety position limiting wire and safety position limiting signal control terminal are attached so that, when the safety position limiting signal control terminal is at the position limiting state, as the motor runs to the position limiting position, it will automatically stop.

Abstract: Embodiments of the invention provide a method of operating a motor connected to a power device having a reduced current rating. The motor can include an increased torque constant and/or an increased back electromagnetic force constant in order to decrease a peak current in relation to the reduced current rating of the power device. The method can include increasing a length of time the motor can operate at the peak current without overheating. A phase angle of the motor can be advanced in order to achieve a continuous operating point with the power device having the reduced current rating.

Abstract: Systems and methods for operating a variable speed drive to receive an input AC power at a fixed AC input voltage and frequency and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter stage to convert the input AC voltage to a boosted DC voltage, a DC link connected to the converter stage to filter and store the boosted DC voltage from the converter stage; and an inverter stage to convert the boosted DC voltage into AC power with variable voltage and the variable frequency. An integral bypass contactor is connected in parallel with the VSD between the AC power source and the AC output power. The integral bypass contactor is arranged to bypass the VSD when the VSD output frequency and voltage are approximately equal with the AC input voltage and frequency.

Abstract: A pumping apparatus for a jetted-fluid system includes a pump having an inlet connectable to the drain, and an outlet connectable to the return. The pump is adapted to receive the fluid from the drain and jet fluid through the return. The pumping apparatus includes a motor coupled to the pump to operate the pump, a sensor connectable to the power source and configured to generate a signal having a relation to a parameter of the motor, and a switch coupled to the motor and configured to control at least a characteristic of the motor. The pumping apparatus also includes a microcontroller coupled to the sensor and the switch. The microcontroller is configured to generate a derivative value based on the signal, and to control the motor based on the derivative value.

Abstract: An accurate slip calculation for providing monitoring and protection to an electric motor. The slip calculation is made using a minimum value of stator resistance as the initial stator resistance, where the minimum value of stator resistance is the minimum value of stator resistance calculated during an initiation period of the motor. The initiation period may be a predetermined time period or a predetermined number of cycles during the motor startup. The initiation period may start after a predetermined settling time or after a predetermined condition is met.

Abstract: The invention relates to a temperature tripping device for reliably shutting down a load, especially a motor, having at least one input for receiving at least one temperature-dependent sensor signal as an input signal, a first evaluation circuit for generating a first output signal if the input signal reaches a preset value, and means for generating a trip signal if the output signal is generated. In addition, a second, redundant, evaluation channel is provided which is supplied with the same input signal as the first evaluation channel and which generates a second output signal if the input signal reaches the preset value, wherein the means for generating a trip signal are connected to the two evaluation channels and generate the trip signal if at least one of the two output signals is generated.

Abstract: An apparatus, system, and method are disclosed for controlling fan speed. A power sensing module senses input voltage and current of a power supply. The power supply includes one or more stages and regulates at least one output bus. A power calculation module calculates input power from the input voltage and the input current. A temperature sensing module senses an ambient temperature and/or a temperature at a component cooled by a fan. A fan speed calculation module calculates a fan speed signal for the fan. The fan speed signal is a function of the input power calculated by the power calculation module and the sensed temperature sensed by the temperature sensing module for at least a portion of a fan speed range. A fan speed transmission module transmits the fan speed signal to the fan and adjusts a fan speed based on the fan speed signal.

Abstract: Provided is a method and apparatus for controlling a motor of a disk drive. The method is used to stably control the startup current of a motor by considering a voltage drop and the disk drive uses the method. The method includes managing power-on reset retry information generated during the startup of the motor and determining the startup current of the motor that corresponds to a power-on reset retry count included in the power-on reset retry information.

Abstract: The invention concerns a switching device system including at least one switching device, signal means and control means. Each switching device includes at least one mobile contact part, an electric motor and, coupling means. The coupling means is arranged to transfer motion from the electric motor to the mobile contact part. The control means is arranged to control the switching device. According to the invention the control means is at least partly remotely located from the switching device. The signal means transmit signals from the switching device to the remotely located control means and vice/versa. The signals represent real-time data and/or off-line data. The invention concerns also a switching device, control means and methods related to the invented system as well as computer program products for such system and electric power system being provided with such system.

Abstract: A system for sensing short circuits and open circuits prior to operation of a motor (i.e., while the motor is in a static state), thereby sparing the electrical system from destructive effects of these electrical problems. In addition, the system may detect a short circuit during operation of the motor (i.e., while the motor is in a dynamic state). Still yet, the system may detect an open circuit at the motor. The motor may be any electromechanical motor, such as a direct current (DC) motor, used in a vehicle or otherwise for controlling motion of a mechanical device.

Abstract: An intelligent air moving apparatus for cooling an electronics enclosure includes a motor for driving a fan at a variable rotational speed and a microcontroller for controlling the rotational speed of the motor. The microcontroller includes a speed sensor for sensing the rotational speed such that when the sensed rotational speed deviates below a target speed, the microcontroller detects a locked rotor condition.

Abstract: Systems and methods for operating a variable speed drive to receive an input AC power at a fixed AC input voltage and frequency and provide an output AC power at a variable voltage and variable frequency. The variable speed drive includes a converter stage to convert the input AC voltage to a boosted DC voltage, a DC link connected to the converter stage to filter and store the boosted DC voltage from the converter stage; and an inverter stage to convert the boosted DC voltage into AC power with variable voltage and the variable frequency. An integral bypass contactor is connected in parallel with the VSD between the AC power source and the AC output power. The integral bypass contactor is arranged to bypass the VSD when the VSD output frequency and voltage are approximately equal with the AC input voltage and frequency.

Abstract: A control CPU generates, in response to a signal STON from a start key, a signal SE at H level and outputs the generated signal to a relay to render system relays ON. Accordingly, a DC power supply is connected between respective neutral points of three-phase coils. When a terminal-to-terminal voltage of a capacitor that is detected by a voltage sensor becomes equal to or higher than a voltage of the DC power supply that is detected by a voltage sensor, the control CPU generates a signal PWMPC1 or PWMPC2 and outputs the generated signal to an inverter. The inverter increases the output voltage of the DC power supply according to the signal PWMPC1 or PWMPC2 to precharge the capacitor to a predetermined voltage or higher.

Abstract: An active sensing and switching device for use in controlling current to a load, comprising a controller means (U1) for disconnecting the load from a power source by providing a switch-open control signal based on a signal indicating a sensed value of electrical current to the load, characterized in that the controller means (U1) determines a nominal value for the electrical current to the load based on monitoring the signal indicating the sensed value of electrical current to the load. A load control system is also provided, including a single ASSD adapted to receive signals indicating sensed values of electrical current to a plurality of respective loads, and further comprising a plurality of load control modules adapted so as to be disposed in proximity to respective loads or a main power line, wherein the load control modules provide respective signals indicating sensed values of electrical currents to the respective loads.

Abstract: A power-window safety device which includes an annular magnet 21 mounted on a rotary shaft (9a) of a drive motor (9) for opening and closing a window glass of an automotive vehicle, and a magnetic flux sensor (20), disposed facing the annular magnet (21), for sensing a change of a magnetic flux developed from the annular magnet (21), which change in flux is caused by rotation of the rotary shaft (9a). The magnetic flux sensor includes Hall ICs (22A and 22B). An operational element (24A, 24B) performs a process of linearly approximating a sinusoidally varying voltage output from a Hall element (23A, 23B) which is provided in association with the operational element, and produces an output voltage (VA, VB) thus processed. Every angular position of the rotary output shaft, or every opening/closing position of the window glass, is detected over the range of one complete rotation on the basis of the output voltages (VA and VB) that are generated through the rotation of the rotary shaft (9a).

Abstract: A control apparatus rotates a drive motor reversely to reverse the moving direction of a roof glass when movement of the roof glass is obstructed by a foreign matter caught in the roof glass while the roof glass is moving toward the closing position, sets a home position of the roof glass by setting the count number to a predetermined value with the roof glass placed in a predetermined position. The control apparatus performs setting of the home position again when the number of times a reverse action of the roof glass originated from catching of the foreign matter in the roof glass has been carried out becomes equal to or greater than a specified number. An abnormality detecting device detects an abnormality in which the reverse action of the roof glass is not carried out at the time when the movement of the roof glass is obstructed, when the abnormality has occurred. When the abnormality is detected, the control apparatus avoids setting the home position again.

Abstract: A method and apparatus for electrically controlling and regulating the movement of an electrically operated aggregate of a motor vehicle, such as a window lifter or sliding roof. A correlation variable for the adjustment force of the aggregate is measured for the purpose of anti-jamming protection. An adjusting movement is switched off or reversed if the adjustment force exceeds a limit value which corresponds to the maximum permissible jamming force. The sensitivity of the anti-jamming system is automatically raised when the motor vehicle is at a standstill. A rough road filter is preferably deactivated so that in the event of jamming, an adjusting movement is switched off or reversed without any time delay. The highest possible level of safety is provided using anti-jamming protection when the vehicle is at a standstill.

Abstract: A motor control apparatus for a reversible motor of a railway switch machine includes a conditional power source having an output voltage. A motor control circuit includes inputs for inputting the voltage from the power source, inputs for inputting a normal signal and a reverse signal, two output terminals for electrical connection to two input terminals of the reversible motor, and a relay logic circuit including a pair of double pole, double throw relays. The contacts of these relays: (a) output the voltage to the two output terminals in response to the normal signal, (b) output an inverted polarity of the voltage to the two output terminals in response to the reverse signal, and (c) short the two output terminals in response to absence of both of the normal and reverse signals.

Abstract: A squeeze protection system for movable parts of a vehicle, includes an operating switch for one or several parts to be moved, one or several actuators assigned to the operating switch, a control device for the actuator or the actuators which receives a signal from the operating switch, and a device for determining an irregularity during the movement of the movable part which device is coupled with the control device. In order to ensure a secure closing of the movable part also in the event of an operating disturbance, it is provided that, when the operating switch is activated and an irregularity is detected during the movement of the movable part, the movement is first interrupted and is then continued at a higher switch-off threshold.

Abstract: A window obstruction identification system is tailored to better identify obstructions at start-up. The limit at start-up is set based upon the first peak value in a direction away from the direction expected for an obstruction. In the case of monitoring speed, the limit is set based upon the first upper peak. The limit is set to be a scaler far less than 1 times this peak. In this way, the limit does not vary with the upcoming expected valleys. In the prior art, an obstruction at start-up was sometimes identified as an expected valley, and thus not quickly identified. In a second embodiment, current is monitored. In a current monitored system, it is the first valley which is utilized to set the limit. In such a case, the valley is multiplied by a scaler which is greater than 1. The disclosed system also accounts for system hysteresis by setting the scaler value to two different values based upon prior movement if the system is subject to significant hysteresis.

Abstract: A combination circuit breaker/motor starter includes a circuit breaker trip unit having a microprocessor and at least one removably connectable contactor or other functional module. The functional module is encoded with an identifier, such that the microprocessor can determine the type of functional module and appropriate configuration parameters, such as trip times, for the particular application of the functional module. Power is supplied continuously to the trip unit during motor overload or short circuit conditions.

Abstract: In an arrangement for detecting pinching situations in electric drives, provided in particular for window and sunroof openers in motor vehicles, the voltage induced in the armature of the motor is used, the induced voltage being determined from the voltage across the motor terminals and the current flowing in the armature, in particular as the difference between the voltage across the motor terminals and the product of the armature current by the armature resistance which is obtained periodically whenever possible. The armature resistance is obtained from the voltage across the motor terminals and the blocking current of the motor, the latter being determined by extrapolation of the armature current determined at a certain point in time. The armature current is measured using a shunt resistor and optionally amplified, and the current signal obtained is averaged using a microcontroller-controlled integrator with adjustable, computed integration periods, and digitized using an analog-digital converter.

Abstract: A conventional method for driving a servo-motor carried out control by means of a current feedback loop, using a current sensor and an A/D converter; therefore, the number of parts was great, cost reduction was difficult and it was difficult to avoid control errors caused by errors in the precision of the current sensor.A method for driving a servo-motor of the present invention comprises detecting a power voltage (V) of a servo-motor (4), controlling a voltage command (Vcmd) to a power converter (3) by numeric calculation using a detected value (Vcc) of this power voltage (V), and controlling power of a drive current (Iu, Iv, Iw).

Abstract: An express down vehicle window lift motor drive system in which an overcurrent detection circuit (10) interprets the flow of electrical power to the lift motor when the motor current exceeds a threshold which is set dynamically as a function of motor in-rush or peak current. Motor current is measured as a small voltage drop across a current shunt. When the current level rises above the dynamically set threshold energization of the motor is halted.

Abstract: Apparatus for electronically producing a torque dependent signal for a plural drive phase synchronous step motor, without the use of an accelerometer or other external feedback device, includes a circuit for detecting respective instantaneous terminal voltage signals for at least two phases of the motor; another circuit for detecting respective instantaneous phase current signals for said at least two phases; and a signal processing circuit for combining the detected signals to produce said torque dependent signal.

Abstract: A method and apparatus for assessing the efficiency of an in-service motor. The operating characteristics of the in-service motor are remotely measured. The operating characteristics are then applied to an equivalent circuit for electrical motors. Finally the equivalent circuit is evaluated to determine the performance characteristics of said in-service motor. Based upon the evaluation an individual is able to determine the rotor speed, power output, efficiency, and toque of the in-service motor. Additionally, an individual is able to confirm the calculations by comparing measured values with values obtained as a result of the motor equivalent circuit evaluation.

Abstract: A method for monitoring the condition of electrical-motor-driven devices. The method is achieved by monitoring electrical variables associated with the functioning of an operating motor, applying these electrical variables to a three phase equivalent circuit and determining non-symmetrical faults in the operating motor based upon symmetrical components analysis techniques.

Abstract: A vehicle-mounted motor drive apparatus which stops the rotation of a motor immediately after an object obstructs a movable part driven by the motor. The drive apparatus includes a motor drive device for selectively driving and stopping a motor, an electric current measuring device for measuring a value of electric current flowing through the motor, a change-in-current-value detecting device for detecting an incremental change in the motor current, and a motor control device for supplying a first control signal or a second control signal to the motor drive device. The motor drive device continuously drives the motor according to the polarity of the detected increment of the current value in response to the first control signal, and immediately stops driving the motor in response to the second control signal.

Abstract: An electronic control for a motor which eliminates the motor centrifugal switch and more particularly a control for a domestic refuse compactor which permits the user to control the approximate full trash bag weight and obtain more compaction from a split phase induction drive motor. A ferrite core sensor on the main winding of the drive motor samples the lagging phase angle of the motor main winding current during a compaction stroke. A low force cycle is achieved by terminating the stroke as soon as phase samples fall below a threshold defined at the start of each cycle by a locked motor main winding phase sample acquired prior to starting the motor. A medium force cycle terminates the stroke when compaction forces exceed the main winding breakdown torque.

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: Motor protection relay is taught in which a microprocessor is utilized in conjunction with a reduced voltage motor starter and the electrical motor system which it operates upon to cause the motor to start in stages. The microprocessor-based system infers a start by the presence of a minimal amount of electrical current flowing in the three-phase system which supplies power to the motor starter and thence to the motor. After the start has been inferred, the microprocessor controlled protection device will issue a transition command for the second stage of the start operation where higher voltage is placed across the motor terminals when the in-rush current has fallen to a predetermined programmable value which approximates full load current, for example. An "incomplete sequence" feedback line is provided which is supplied from the auxiliary contacts of the low voltage starter to the microprocessor.

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: The power supply to an electric actuating motor is regulated by reducing the differences between current intensity or voltage and a reference value. Two transducers measure the current intensity and the voltage. A selection stage chooses the higher of the two values and a comparison stage delivers a difference signal with respect to the reference value established by a stage of the potentiometer type. A regulator produces an action which is compared within a comparator with a sawtooth signal emitted by an oscillator. Depending on the sign of the comparison, a control stage supplies the motor during a variable fraction of the period of the oscillations.

Abstract: A water pump protector which includes electrical circuitry through which an electric motor is energized. The electric motor operates a water pump. The circuitry senses the phase angle between the voltage and the current applied to the electric motor. When the phase angle indicates that the motor is operating without a load, the circuitry deenergizes the electric motor. Thus, the water pump is protected against damage which may occur when the water pump is operated without pumping water.

Abstract: A motor protection circuit which generates a signal having a value proportional to the magnitude of the input current of the motor and a motor speed signal having a value proportional to the difference between the rated motor speed and the actual motor speed. The motor speed signal is multiplied by the input motor current proportional signal to derive a product signal. The product signal is summed with the input motor current proportional signal to derive a sum signal. The sum signal is compared with respect to a preset level to determine if it is greater than a preset level. If it is greater than a preset level, the sum signal is coupled to the input of a voltage controlled oscillator which generates an output signal having a value proportional to the magnitude of the sum signal. The output of the voltage controlled oscillator is counted in an up/down counter and an output is gated when the total count reaches a predetermined level.

Abstract: A controlled switch 4 provides current pulses derived from a battery 3 to a motor 1, having a series field 2 under command of a control unit 8 which provides command pulses for repetitive closing of the controlled switch 4. Current through the motor is sensed by a sensing resistor 6 and connected to a safety circuit 9 which, upon sensing of current flow in the absence of a control pulse from the unit 8, disconnects current to the motor by opening a controlled switch 5. To distinguish between (a) current flowing from the battery 3 l and (b) circulating current flowing during pulse gaps in a free-wheeling diode 7 connected across the field and armature of the motor, voltage across the free-wheeling 7 is sensed, thereby effectively sensing the conduction state of the free-wheeling diode and, if the free-wheeling diode is conductive, disabling the safety circuit to prevent spurious operation thereof during flow of inductive, circulating current through the bypass or free-wheeling diode under normal operation.

Abstract: A control circuit for turning off the power to the pump drive motor when the pump has exhausted the supply of liquid in the well. Means for sensing the instantaneous current to the pump motor and a circuit measuring the average current drawn by the pump drive motor, and turning off the power when the average current decreases below a preset level. An RC circuit having a time constant greater than the time required for the pump to complete one full pumping cycle for measuring the average current to the motor, and a comparator controlling switching means to shut off the power when the average current to the motor decreases to a predetermined amount. A reference voltage supplied to the comparator from an amplifier connected to the electrical power in which the output of the amplifier varies inversely to variations of the voltage of the electrical power thereby preventing fluctuations in the supply voltage from adversely affecting the control circuit.