Abstract: An automated SCR cell test exercises each of the twelve SCRs in a dual, 3 phase, full wave SCR rectifier bridge singly to detect shorted SCRs and in pairs to detect open SCRs or faulty gate circuits.

Abstract: An inverter receives a d.c. voltage and delivers to an X-ray tube, by way of a high-voltage transformer, filter, and rectifier, a high-voltage d.c. output. The inverter is driven in response to control signals which are responsive to the difference between a voltage demand signal and a voltage feedback signal. The control signals are also responsive to various status conditions of the system which are monitored by a microprocessor. Inputs to the microprocessor include various signals which are indicative of voltage or current conditions. In this way, such conditions as an over-voltage at the output, an unbalance between the anode and cathode with respect to ground, or an excessive current flow are detected and precautionary measures are quickly taken to prevent further damage to the system.

Abstract: Method and apparatus is disclosed for automatically processing visual images electronically so as to permit intelligent machine analysis of the image content. A special distributed logic system architecture facilitates rapid real time image analysis and the production of reaction control signals in a high speed production line environment, for example. Dedicated decision logic is employed to determine in but a single micro-instruction cycle whether a detected corner point of the image should be linked to another already linked chain of such corner points so as to define part of a closed edge contour of the image under examination. This ability to so rapidly classify encoded corner points as either belonging or not belonging to a given set of such corner points which describe a closed edge contour is quite useful in achieving rapid real time image analysis capability.

Abstract: An electrical circuit for providing an adjustable and highly controllable, high voltage AC waveshape to a load from a low-voltage, DC source. This highly controlled waveshape allows accurate reproduction of almost any low-frequency AC reference through an intermediate high-frequency inverter. The inherent leakage reactance of a high-voltage transformer is used advantageously as a filter for removing the undesired high-frequency component from the output. Economy in parts count and power losses results from the use of a single power handling inverter to perform all adjust, regulation, and waveshape functions.

Abstract: A high-voltage capacitor, particularly for use in a voltage divider, is made from a high-voltage lead cable and a metallic component surrounding the cable for some distance along the length thereof, the metallic component being fixedly secured to a printed circuit board. The cable center conductor serves as the first capacitor plate while the metallic component serves as the second plate. In another aspect, the high voltage capacitor described above is incorporated into a high-voltage divider assembly which includes a voltage divider resistor assembly and a low-voltage capacitor.

Abstract: Dynamic response of an a-c induction motor control system including an adjustable frequency and adjustable magnitude power source is made more stable during the transition from a motoring to an electrical braking mode by modifying the system characteristics as a function of rate of change of motor flux and torque magnitude during electrical braking. The control system responds to a torque command signal and a torque feedback signal to generate an error signal which controls the frequency of the excitation supplied to the motor and thus the torque developed by the motor. During electrical braking this error signal is modified as a direct function of the rate of change of motor flux and as an inverse function of the magnitude of torque developed by the motor. During the transition from motoring to electrical braking, when the system tends to be unstable, the rate of change of flux is relatively high while the motor torque is at a relatively low value.

Abstract: A multi-axle traction vehicle is equipped with apparatus for sensing the speeds of its respective drive axles, and control apparatus is provided for producing a predetermined warning signal if the sensed speed of one and only one of the axles is less than a predetermined low threshold level. In addition, apparatus is provided for inhibiting the control apparatus unless all but one of the sensed axle speeds are greater than a predetermined higher threshold level thereby minimizing the opportunity of producing a false warning signal.

Abstract: An improved Franklin tester for measuring surface insulation resistivity on magnetic sheets. The contact fingers of the prior art tester are modified to accommodate an articulated contact tip. The articulated tip pivots when the tester is clamped on a magnetic sheet to thereby maximize the area of contact. Preferably the articulated tips are formed of stainless steel to overcome the rapid deterioration of the prior brass contact fingers.

Abstract: Apparatus for providing firing signals to a phase controlled rectifier circuit at a time at which valves in the rectifier circuit are forward biased without the need for providing continuous firing signals. The apparatus monitors the voltage applied across the rectifier valves and provides a signal when a valve is forward biased. This signal is applid to a gating circuit which determines whether a normal phase control firing command was initiated prior to the time the valve became forward biased. If such a command was initiated, the gating circuit passes the signal to a valve firing circuit which provides firing signals to the rectifier circuit. If the firing command was not previously initiated, the signal is inhibited and firing signals are subsequently applied to the rectifier circuit upon receipt of a firing command.

Abstract: A wheel slip correction system of the type in which boost current is supplied to the field winding of a d-c electric traction motor driving a slipping wheel from an a-c source in order to correct the slip is provided with a control system which automatically inhibits the application of boost current if control power fails. A current transformer connected to provide power to the field winding from the a-c source has a secondary winding normally short-circuited by inversely paralleled thyristors thus inhibiting power transfer to the field winding. The thyristors are maintained short-circuited by a current amplifier connected across the transformer secondary and adapted to normally supply current to the gate terminals of the thyristors. The current amplifier is inhibited by receipt of a wheel-slip signal so that the thyristors remain non-conductive and boost current is supplied to the motor field.

Abstract: Apparatus for increasing the available regenerative braking energy and for enabling low current control without frequency variation in a time-ratio controlled main thyristor power circuit for a direct current traction motor. A variable impedance element is serially inserted in a motor armature free-wheeling current path between a free-wheeling diode and the motor armature, the variable impedance element preferably comprising a power resistor and parallel connected thyristor. During electrical regenerative braking the thyristor is used to modulate the power resistor to thereby present a continuously variable impedance in the armature current path. During motoring at very low speeds the thyristor can be operated to modulate the power resistor and thus reduce the minimum controllable level of motor current normally limited to commutation current level without the necessity of reducing the main thyristor operating frequency.

Abstract: A highly regenerative electrical brake control system including a variable time ratio power conditioning circuit for regulating braking effort of a direct current electric traction motor in a traction vehicle. The system includes a plurality of switches adapted for connecting the power conditioning circuit in a series path between the motor and a power source during high speed braking whereby the power conditioning circuit steps-down the motor generated voltage magnitude to match the power source voltage magnitude without using series connected resistors for voltage dropping. During low speed brake the switches are effective to reconnect the power conditioning circuit in a shunt arrangement with the motor whereby the motor voltage magnitude may be stepped-up to match the higher voltage magnitude of the power source. In a further embodiment provision is made for blending of dynamic and regenerative electrical braking when the power source is not totally receptive to motor generated current.

Abstract: The stator terminals of an adjustable speed a-c induction motor are connected to a source of d-c electric power by means of an inverter, and a system is provided for blending both dynamic and regenerative electrical braking of the motor whenever it decelerates. The brake blending system comprises a plurality of braking resistors respectively coupled by a corresponding switch in parallel with the power source. The switches are controlled by a control circuit which responds to motor terminal voltage, motor angular velocity and the difference between the commanded and actual motor torques to determine the additional current which the motor could regenerate without exceeding commanded parameters. When the additional current corresponds to that current which can be absorbed by adding an additional stage of braking resistance, the control circuit actuates a switch to add a stage of dynamic brake resistance.

Abstract: Apparatus for electronically simulating the response of a direct current traction motor to predetermined operating states whereby there is provided a resultant signal representative of the torque that would be produced by an actual motor operating in the prescribed states. The apparatus calculates E per RPM for the simulated motor from measured values of available armature voltage and armature velocity. A function generator thereafter converts the E per RPM signal to a signal representative of the motor field current based upon known values for the simulated motor. The field current signal is converted to an armature current signal by a circuit which responds to the motor commanded state of field weakening to compute the instantaneous ratio of armature current to field current under the commanded conditions and thereafter multiplies the field current signal by that ratio to obtain a signal representative of armature current.

Abstract: A method and apparatus for rapidly detecting acceleration variations in a moving object by monitoring the instantaneous velocity of the object. A signal representative of instantaneous velocity is operated on to derive signals representative of average acceleration, instantaneous acceleration and predicted velocity. The average acceleration and instantaneous acceleration signals are compared to determine acceleration changes. In a preferred embodiment the invention is applied as a wheel slip/slide detector in a traction vehicle and a signal generated when the instantaneous acceleration deviates from the average acceleration by a predetermined magnitude is utilized as a wheel slip/slide signal to implement corrective action to the power control system of the vehicle. Upon generation of the wheel slip/slide signal, calculation of average acceleration is inhibited to prevent its influence by the sudden acceleration change.

Abstract: A d-c motor drive system, useful for propelling and retarding electrically propelled traction vehicles, wherein the armature winding has a first terminal coupled through an armature chopper to a first polarity conductor of a d-c source, and a second terminal coupled through a breaker switch to a second polarity conductor of the d-c source. First and second controlled rectifiers are connected across the first and second conductors in a self commutating circuit such that they conduct sequentially and alternatively. Means are provided for varying their respective conduction time intervals to control the voltage at their junction. Field winding means are coupled from the junction of the controlled rectifiers to the junction of the armature second terminal and the breaker. During the motoring mode with the breaker closed field current flows in a first direction.

Abstract: Method and apparatus for effecting control of a complementary impulse commutated inverter to enable start-stop operation without power removal and to avoid start-up failures caused by inductive load flux saturation. The invention utilizes a gating logic circuit to always start inverter operation by gating a first predetermined switching element. The gating logic circuit responds to a stop command by terminating operation in a half-cycle in which the first predetermined switching element is not carrying load circuit. In one embodiment upon receipt of a stop command the gating logic circuit terminates inverter operation by applying a last gating signal to the first predetermined switching element, the last gating signal having a time duration less than that required after receipt of a gating signal for current reversal in the inductive load.

Abstract: An electrical propulsion control system for self-propelled traction vehicles having an electric generator supplying energy to separately excited traction motors, each motor field being normally excited with a substantially constant field excitation providing magnetic saturation such that motor load variations produce minimal changes in back emf, and means for equally boosting the excitation of each motor field responsive to the largest one of the individual motor armature currents exceeding a predetermined magnitude which is greater than the maximum attainable armature current during dynamic retarding operation.

Abstract: An improved digital differential analyzer (DDA) circuit wherein the output pulses, representing incremental changes of an integral, are generated at a rate as determined by a remainder size number. An integrand counter responds to pulses representing an incremental change of the integrand to keep track of the correct value of the integrand. Upon the occurrance of a pulse representing an incremental change of the variable of integration the present value of the integrand is added to the number stored in a remainder register thereby generating a new remainder number. The new remainder number is compared to the programmed remainder size number and if the new remainder is equal to or greater than the remainder size number a pulse representing an incremental change of the integral is generated and the new remainder is modified by subtracting the remainder size number from the new remainder number.