Abstract: A drapery opening and closing system is provided for draw drapes which are movable over a traverse member between an open and closed position by use of a drape drive system. The opening and closing system has limit switches positioned to be activated when the drapes are opened and closed. A manually settable timer connected to a power source applies power at preset times to a reversible motor via a control circuit. The control circuit is comprised of a relay activated by the timer and a series connected two-section switch. Outputs of the two-section switch are connected to the reversible motor through the limit switches. When the timer is triggered at a preset time, the drapes automatically open or close. Via the two-section switch, the drapes may be manually activated to open or close at times other than the preset times on the timer.

Abstract: During machine tool operation a first set of sensors, referred to as cutter deflection sensors, provides data which is representative of the physical deflection of the cutting tool from a rest position, while a second set of sensors, referred to as position sensors, provides data which is representative of the position of the workpiece mounted on the machine tool relative to a reference or setpoint position. The cutter deflection and workpiece position data are combined to produce a resultant which is representative of the actual position of the cutting tool relative to the workpiece. This resultant is then compared with reference data which is representative of the desired position of the cutting tool relative to the workpiece. The difference between the actual and desired positions is then compared with a preselected tolerance value.

Abstract: An electronic control arrangement which can be used in particular for driving brushless and slip-ringless electric motors and an installation incorporating such an arrangement. The speed of the motor is controlled as a function of one of more items of information such as temperatures for example. For this purpose, a DC control voltage proportional to the items of information received is produced. By combining a mixing arrangement, a processing block, a function generator and a power-amplifier stage it becomes possible to obtain from the output of the arrangement, from a source of DC electrical energy, two sinusoidal voltages of the same amplitude and frequency which are 90.degree. out of phase with one another and whose frequency and amplitude are proportional to the DC control voltage.

Abstract: Apparatus for controlling the starting of a three-phase, salient pole, synchronous motor employs a signal representing slip frequency obtained from a power sensor connected to the motor supply. It requires no connection to the field coil or to other motor component. Since the signal can be obtained from a power sensor, the starting can be controlled from a location remote from the motor, for example at the motor control switchgear. A detector determines when the signal has decreased in frequency to a point representing a rotor speed where field excitation should be applied and it provides an output control signal. This control signal causes field excitation to be applied. In its broadest sense the apparatus may be used to indicate slip frequency remotely.

Abstract: Disclosed is a stepping motor control utilizing a microprocessor. The control is suitable for driving one or more stepping motors one at a time or in unison. In the illustrated embodiment when plural motors are driven together they are driven at the same rate or at rates in a fixed proportion to one another although several of the features of the invention are suitable for use in circuits providing contouring control; i.e., where separate motors are driven at separate stepping rates proportional to the relative distances each is to traverse for a single movement. An acceleration/deceleration circuit is utilized which provides simple yet highly accurate and efficient control of the stepping motors. Feed rate compensation for simultaneous drive of two motors is provided. Also a means is provided to allow stepping rates in excess of the counting rate capability of the microprocessor.

Abstract: Two transistors each have their emitter-collector circuits coupled in series between one end of a motor field winding and the opposite terminals of a D.C. voltage source to switch current flow in either direction through the winding. Two current sensors are provided, one coupled in series with each emitter-collector circuit. The voltage developed across each current sensor is applied through a driver circuit to the base of the other transistor so as to cut one transistor off when the other is conducting and vice versa, thereby eliminating the possibility of having both transistors conduct simultaneously which would short out the voltage source and burn out one or both transistors.

Abstract: A control apparatus for use in a synchronous machine having a field and an armature windings, one of the windings being provided on a stator and the other winding on a rotor comprises a thyristor converter for feeding the armature winding with electric power. A rotor position detector, an actual current detector and a rotating speed detector are provided. A current pattern signal is produced on the basis of the rotor position signal and the rotating speed signal and is compared with the actual armature current. A gate pulse generator controls the thyristors of the thyristor converter in accordance with the difference between the current pattern signal and the actual armature current signal. A phase shifter is provided for shifting the current pattern signal. A phase detector detects the phase difference between the armature current supplied for the armature winding and the rotor position, and the phase shifting operation of the phase shifter is controlled in accordance with an output from the phase detector.

Abstract: A bi-directional motor drive circuit has a single input terminal and first and second terminals having a reversible DC electric motor connected therebetween. Also, the circuit is provided with third and fourth terminals for connection to voltage sources of unequal positive potential such that the voltage supplied to the third terminal is at higher potential than that supplied to the fourth terminal. Further, the fourth terminal is connected to the second terminal. The circuit splits into first and second branches. The first branch includes a first NPN transistor and a second PNP transistor. The second branch includes third and fourth NPN transistors.

Abstract: An electronic signal proportional to Icos.theta. for an induction motor is substantially proportional to the mechanical power output of the motor. This signal is detected by rectifying a signal which is an analog of motor current in phase with the motor voltage and time averaging the rectified signal. Comparing the averaged signal to a reference level permits the interruption of motor current for an underload or an overload condition. The circuit permits detection of excessive ice formation on the outdoor heat exchanger of a heat pump system. The circuit is connected to the impeller drive motor which forces air across the heat exchanger and stops the motor and initiates the de-ice procedure when the ice blockage causes mechanical power delivered by the motor to deviate to a selected level.

Abstract: The step motor control system comprises triggers and a trigger starting and switching sequence preselection unit.The unit inputs are connected to a second output of each trigger, and the outputs are connected to the inputs of each trigger. The system also includes a decoder of inoperative states of the triggers and power amplifiers. The unit comprises a trigger starting circuit for setting up the amount of rotation of the step motor shaft comprising an individual bus connected to timing inputs of the triggers and means for trigger switching sequence preselection for setting up the rotational direction of the shaft. Said means has a first group of NAND gates, the number of gates being equal to the number of triggers, each gate having its first input connected to the second output of one of the triggers, and its second input connected to the bus for setting up the shaft's rotational direction.

Abstract: A switching circuit for automatically restarting a vehicle engine upon stalling including a normally open vacuum relay connected to the intake manifold of the engine which closes in response to stalling of the engine to electrically connect the vehicle battery to the cranking solenoid of the engine and to simultaneously cause actuation of a solenoid-operated fuel valve element to admit fuel to the engine to prime it. An auxiliary circuit is provided to maintain the valve closed after the engine restarts to prevent a discontinuity in the fuel supply.

Abstract: A light emitting indicating circuit comprises a first and second inverter circuit which are each comprised of a pair of complementary transistors connected in series. A motor driving coil and a capacitor are connected in series between respective outputs of the inverter circuits, and the inverter circuits are effective for applying repetitive complementary electrical driving signals for repetitively flowing a current in alternating directions through the series combination of motor driving coil and capacitor to repetitively energize the motor driving coil. An indicating circuit responsive to the electrical driving signals indicates energization of the motor driving coil. The indicating circuit is comprised of a light emitting diode connected in parallel with the motor driving coil for emitting light to indicate energization of the motor driving coil.

Abstract: Speed control for a brushless d.c. motor is made independent of the effects of temperature and aging on the magnetic structure by triggering a rectangular wave pulse generator by voltages produced by the rotation of the motor through a coupling network that makes the trigger time correspond to a certain portion of the rise of voltage so that the influence of the amplitude of the signal on the trigger time will be negligible. The square waves are phase-shifted and integrated to produce a d.c. signal proportional to motor speed on which is superimposed a practically sinusoidal ripple and this signal is fed into a comparator to produce both an error signal from the d.c. component and a commutation control from the a.c. component. The speed is switched between desired precise values by an electronic circuit that controls the duration of the rectangular pulses and makes corresponding adjustments in the integrator and phase shifter.

Abstract: A control circuit for use with a shuttle car used in mining operations and circuitry associated therewith. The control circuit generally comprises a chopper circuit in series with a reversing circuit and a traction motor which drives the shuttle car. The chopper circuit essentially comprises two separate current paths each through a separate set of silicon controlled rectifiers or SCRs and a common capacitor. A logic circuit controlled by the operator alternately gates the sets of SCRs thereby placing voltage across the traction motor. The magnitude of this voltage and hence the speed of the motor are directly proportional to the frequency of the gating pulses. The reversing section also employs two sets of SCRs and a common field inductance. The operator, through the logic circuit, triggers one set of SCRs and current flows through the field inductance in a forward direction causing the traction motor to operate in a forward mode.

Abstract: An electric motor attachable to a photographic camera for shutter rewind and film transport. The output shaft of the motor acts on the main shaft of the camera and has no further operational connection with the camera shutter. The electric motor (8) proper is rotatably supported in the housing (7) so that the stator of the motor rotates oppositely to the direction of rotation of the rotor when the rotor is locked into position at the end of the shutter rewind and film transport. A switch for the motor circuit is actuated by the backward moving stator.

Abstract: The invention relates to a starting device for an asynchronous motor in which device a capacitor and a PTC resistor form a series circuit. A housing has three chambers formed by two interior walls and a cover. The capacitor is in one end chamber, the PTC resistor in the middle chamber, and the lead ends which are connectable to a motor winding in the other end chamber. The PTC resistor is subject to heating and the housing has vent holes for ventilating the middle resistor chamber.

Abstract: A marine ground isolator for selectively completing the current path through a ground connection. The herein illustrated embodiment includes a switch circuit connected in series between two portions of the ground connection and arranged so as to complete the current path therethrough only in response to an applied control signal; and means for monitoring the potential between the two portions of the ground connection and for applying the control signal to the switch circuit only when the absolute magnitude of the dc potential exceeds a first value or when the ac potential exceeds a second value.

Abstract: A voltage waveform synthesizer whereby an ac waveform (which may be varied in frequency) is synthesized from dc or unidirectional voltages in a programmable fashion, the power carried by the waveform being controllable from zero to some maximum value and the harmonic content of the waveform also being controllable. The synthesizer per se is described and it is shown in combination with a rotating electric machine to provide, for example, a variable speed drive mechanism.

Abstract: An electrical control circuit for a single phase induction motor which uses relay operated reversing contacts to ensure that the motor reverses its direction of rotation upon each energization thereof.

Abstract: A controller minimizes periodic torque or force perturbations in an inductor-type synchronous motor drive by supplying current waveforms to each motor phase that contain a fundamental frequency component and selected harmonic components. The harmonic components in the phase currents heterodyne with the periodic permanent magnet flux fundamental frequency to create periodic torques or forces which subtract from the unwanted torques or forces perturbing the moving portion of the motor. The controller, which includes an interpolator, a memory, and a converter, provides for smooth incremental movement of a member such as a plot head, at substantially constant velocity, by applying selected continuous periodic waveform signals as phase currents to the windings of inductor-type synchronous motors.