Abstract: A photo-optical coupler is connected to a shaft to provide a series of electronic pulses at a frequency corresponding to rotational velocity of the shaft. Apparatus electronics is responsive to frequency of such pulses for indicating a low speed alarm condition when such frequency is below a preselected threshold. The apparatus electronics includes a digital counter that is set to a first preselected count upon occurrence of each of the shaft rotation pulses, and which is thereafter decremented between the shaft rotation pulses. A low speed alarm condition is indicated if the counter reaches a count of zero prior to a succeeding shaft rotation pulse. In the preferred embodiment, the counter is decremented by an oscillator having a clock frequency coordinated with the first preselected count so as to activate the alarm when rotational velocity of the shaft decreases to a predetermined threshold percentage of a nominal rotational velocity of the shaft.

Abstract: An automobile alternator regulator integrated circuit having a voltage-supply or -sense node (6) for connection to an external voltage, and a voltage clamp comprising: a pnp bypass transistor (Q1) having a base electrode, an emitter electrode coupled to the node and a collector electrode coupled to ground; a resistor (R1) connected between the base electrode and the node; a Zener diode (Z1-Z4) connected between the base electrode and ground for enabling the bypass transistor when the voltage at the node exceeds a predetermined value, whereby the voltage at the node is clamped to a voltage no greater than the predetermined value; and a fuse (F1) connected between the node and the emitter electrode so as to provide a subsequently identifiable cause of failure if the fuse becomes blown due to excess voltage while allowing subsequent operation of the integrated circuit if the clamp means fails but another part of the integrated circuit remains functional.

Abstract: A method and apparatus for detecting a failure in the speed sensing system of a rotating shaft prime mover. The control system for the rotating shaft prime mover includes a speed sensing system for measuring the rotational speed of the shaft, a speed feedback system for providing actual rotational speed, and a monitoring system for monitoring the speed sensing system. The monitoring system detects loss of speed signal and overspeed conditions. The speed pickup sensing system includes at least a first, second and third speed sensor. The monitoring system senses with the speed pickup sensors the rotational speed of the shaft to provide signals representative thereof. It selects between the first and second speed signal the signal representative of the actual rotational shaft speed to produce a primary speed signal. The system compares the primary speed signal to the third speed signal for producing a speed feedback fault signal when the primary signal deviates from the third signal by a predetermined value.

Abstract: The present invention provides a power supply for lighting an incandescent lamp with high-brightness, comprising connecting a time constant circuit, rectifier, switching device so that the output of the rectifier is supplied to an incandescent lamp through the impedance for a period, determined by the time constant circuit, and that the switching device conducts and shorts the impedance after a lapse of the period to allow the incandescent lamp to receive the output of the rectifier by bypassing the impedance.

Abstract: In an electrically-powered tool, the driving motor of the tool and a switching element for a phase control circuit for controlling the number of revolutions of the motor are connected in series. The switching element is fixed to a field core of the motor. In the phase control circuit for the switching element, a bias resistance between the base and the emitter of a pulse phase controlling transistor for changing the amplification degree by the output from a pulse generating circuit for generating pulses having frequencies corresponding to the numbers of revolutions of said motor is connected in parallel with a capacitor for effectively slowly starting said motor, a first amplifier for changing the output in response to the number of revolutions of said motor and for stabilizing the rotation of said motor, and a second amplifier for producing output upon falling of the number of revolutions of said motor below the preset number of revolution and for limiting overload current.

Abstract: In an idling controller, particularly for automotive vehicles, there are present both a control amplifier with integral time portion (3) and a limiter (6) with proportional time portion. The inputs of the limiter are acted on by the correcting variable from the output of the control amplifier and by a limiter reference variable formed with the actual-speed value. The output of the limiter is fed back to an input of the control amplifier. In order to obtain the desired time action of the idling controller upon sudden drops in speed, at least one time member (12) with differential time portion is provided between the input (1) of the actual-speed value and the output of the limiter (6). The limiter (6) is so dimensioned and coupled with the output of the control amplifier (3) that, upon a drop in speed beyond a predetermined value, the correcting value (y) is controlled by the output variable of the limiter (6) (control limit).

Abstract: Disclosed is an overspeed protective apparatus for an electric motor having pairs of stator windings normally connected in parallel, the apparatus having an actuating mechanism responsive to an overspeed condition of the motor and an electrical switching assembly normally connecting the stator windings in parallel but adapted upon actuation by the actuating mechanism to interrupt the parallel connection and connect pairs of windings in series.

Abstract: A circuit arrangement for windshield wiper motor protection including circuits for pulsing the motor with a variable pulse interval pattern. The pulse interval is generated by circuits which are responsive to motor speed from a comparison with a reference. The motor is automatically deenergized when it is overloaded or stalled.

Abstract: The disclosure sets forth trip circuitry for a rotating shaft machine which includes redundant overspeed protection and means for testing the overspeed protection circuit while the machine remains in operation. Moreover, further protective circuitry is provided for detecting a failure in the speed sensing system. The overspeed protection and the speed sensing failure circuit are each connected to a relay system which may actuate a trip servo valve to a closed position.

Abstract: In a speed feedback control system wherein a speed command signal and a speed feedback signal are compared and wherein the deviation between these signals is entered into a speed control unit, the speed signal is differentiated to apply speed damping in order to suppress the oscillations of the control system. In this case, while the speed command and the actual speed make a great difference transiently, the speed command is approximate to the sum between the speed feedback signal and the damping signal even transiently. Therefore, the speed command signal is compared with the sum between the speed feedback signal and the damping signal, and the fault of the speed control system is detected upon the fact that the deviation has exceeded a predetermined value.

Abstract: A speed switch control comprising a subfractional permanent magnet AC generator generating an AC signal varying in amplitude with saft speed variations; the AC signal is rectified and compared with a regulated DC reference to generate first and second threshold signals indicative of shaft speeds over and under a critical value. A switch actuator circuit develops "on" and "off" switch actuator signals, from the threshold signals to actuate a two-terminal solid state switch between on and off conditions; the "off" signal is continuous but the "on" signal is a high-duty-cycle semi-continuous signal including brief recurring "off" intervals. A power storage/supply circuit, connected in parallel with the switch terminals, which recharges during switch "off" intervals, affords the power supply for the threshold and switch actuator circuits.

Abstract: An over-speed preventing apparatus for the DC motor comprises a DC motor the speed of which is controlled by the adjustment of the armature voltage thereof, controlled-rectifier means for supplying power to the separately excited field winding of the motor, means for generating a predetermined field current command, means for detecting the field current, and a constant current control system for controlling the rectifier means in accordance with the error between the field current command and the detected value of the field current. The apparatus further comprises a unidirectional element connected in parallel to the field winding in the direction in which the field current is made to flow back, current decrease detector means inserted between the rectifier circuit and the parallel circuit including the field winding and the unidirectional element, and protecting means energized by the current decrease detector means.