Abstract: An apparatus and method relative to the operating of a control turn-off semiconductor device provide for determining the actual control electrode to cathode voltage upon the application of a turn-off control signal by adjusting the apparent value of that voltage by a value representing the voltage drop due to inductance in lead lines. The thusly adjusted value is employed to develop an output signal which indicates that the device has been turned off. In a further embodiment, the output signal may also be employed to reduce the value of the control signal from a first, relatively high value to a second, relatively low value.

Abstract: A system for controlling the operation of an alternating current induction motor having windings supplied by electrical power from the polyphase alternating current source includes a load commutated inverter circuit which is connected between the power source and the induction motor for furnishing electrical power to the motor. Controllers responsive to a command signal and a feedback signal indicative of motor operating parameters control the operation of said load commutated inverter circuit. There is further provided a fixed capacitor circuit connected between the windings of the motor for supplying reactive volt amperes (VARs) to said load commutated inverter circuit and said motor.

Abstract: A knitted glass fiber tube is everted, or turned inside out to convert the usual outward flare which develops at the cut end thereof into a purse mouth which tends to urge the cut end inward against the peripheral surface of a conductor bar passing therethrough. The intimate contact between the cut end of the everted knitted glass fiber tube and the conductor bar resists deposition of conductive contaminants which may otherwise reduce the insulation provided by the everted knitted glass fiber tube.

Abstract: A single microcomputer controls the firing time determination for two independent current regulators for two six pulse AC/DC converters which are part of a twelve pulse parallel controlled current inverter (CCI) AC motor drive. A very short high priority interrupt occurs when a motor channel source converter thyristor fires. This interrupt calls a longer, low priority current regulator interrupt informing it that a master channel source converter thyristor has just been fired. The current regulator causes a count to be loaded into a master fire counter and also loads a firing mask into a hardware latch or buffer. When the master fire counter times out the next thyristor pair of the master channel source converter is fired directly out of hardware. Similarly, there is a separate slave channel fire counter loaded after the current regulator is called by a short high priority interrupt when a thyristor in the slave channel source converter fires.

Abstract: A voltage limiter for protecting the thyristors of a current source inverter, also known as a controlled current inverter, wherein the limiter includes a circuit for sensing the respective voltages directly across at least one but preferably across each of the thyristors in the inverter and generating a signal corresponding to the highest value and a regulator circuit which is operable in response to the difference between the highest value signal and a reference signal corresponding to a safe operating voltage for the thyristors in the inverter, to modify the thyristor gating angle of those thyristors which control the current in the inverter. The voltage limiter thus reduces the current carried by the inverter thyristors when the highest voltage across the inverter thyristors exceeds the reference signal, and thereby reduces the amplitude of any commutating spike voltage in the voltage applied across the thyristors.

Abstract: A shaft voltage suppression circuit is used with electrical motors or generators of the type including a field winding supported by a shaft which is movable within bearings, which motor or generator is supplied by way of relatively positive and negative buses with electrical power from a source including an electrical power conversion bridge having controlled rectifiers and uncontrolled rectifiers. The shaft voltage suppression circuit includes a first series combination of a first resistor and a first capacitor connected between the positive bus and a common voltage. A second series combination of a second resistor and a second capacitor is connected between the negative bus and the same common voltage and a unidirectional current conductor is connected in parallel with the second resistor such that there is established a low resistance path for current to pass from the negative bus to the common voltage.