Abstract: From the sensed input voltages and currents fed into a standard induction motor the stator resistance is known instantaneously through a direct and quadrature treatment of the sensed quantities from which are derived at least four of the following five quantities: the motor overall reactance, the motor overall real impedance, the air gap reactance, the parallel combination of stator and rotor leakage reactances and the stator leakage reactance. This derivation uses the motor intrinsic characteristics at rest, while those four quantities are used in ascertaining the stator resistance instantaneously and recurrently during motor operation, thus, without any sensing means on the motor itself. The load reactance is also determined with the above-stated five quantities.

Abstract: A snubber circuit coupled across each thyristor to be gated in a chain of thyristors determines the critical output of a NOR LATCH whenever one snubber circuit could not be charged and discharged under normal gating conditions because of a short failure.

Abstract: In a computerized numerical control (CNC) or a direct numerical control (DNC) machine tool, the second derivative as a function of time of the net power applied to the cutting tool is used to detect approaching tool failure, and a statistical representation of such occurrences with a series of tools is used to derive instantaneously the percentage of wear experienced by a new tool in terms of the statistically expected critical level of net power.

Abstract: A high frequency current-fed inverter of the series/parallel compensated type is started directly with the main thyristors of the inverter by charging the series capacitor through the input inductor of the DC supply during a first time interval with one pole, by discharging the same during a second time interval with the other pole, then passing to free-running operation at an initial frequency from which load operation can begin. The first and second time intervals are established while a constant DC voltage is being applied so that commutation of the outgoing thyristor is insured. DC voltage regulation is eliminated as soon as the free-running operation has been initiated.

Abstract: A minimum loss multilayer solenoid for induction heating is characterized by the ampere-turns carrying the same current per conductor from one layer to the next on account of the dimensioning of the conductors having width and thickness varying monotonically in opposite directions across the layers. Central cooling for the conductors is accommodated in the parallel layers with sectional distribution of the cooling medium.

Abstract: A synchronous motor drive includes an inverter gating control system using three counters wherein two counters respond to 180.degree. apart zero crossings for providing units of time in terms of clock units, and the third counter is at a computed time interval preset with a count to be counted down to derive the remaining time which is to elapse until a predetermined firing angle is reached, at which time firing of the thyristor of the inverter is triggered.

Abstract: The change in the mill modulus of the stand of a rolling mill due to the particular strip width of a run strip of material is taken into account by reference to the unloaded mill modulus of the stand and a desired roll gap opening is calculated on the basis of an error relative to the actual roll gap opening in order to achieve a desired strip thickness setting.

Abstract: Method and apparatus is described for interacting bulk acoustic waves with an optical waveguide on a common substrate to switch, modulate or deflect guided light at a very high speed. A direct application lies in a monolithic optical analog-to-digital converter. To this effect, a plurality of transducer elements regularly spaced in an array across the optical waveguide are controlled with constant or variable phase shift along a slope, thus causing deflection of the guided light in a fashion analog to phased-array radar technique. A fully integrated monolithic device is constructed combining the bulk acoustic wave generating and optical waveguide functions.

Abstract: In a current-fed static controlled synchronous motor drive which includes a ramp logic for establishing the desired firing retardation for the naturally commutated thyristors, an optical encoder provides a position signal and a velocity signal, while the ramp counting the velocity pulses is automatically aligned with the position signal by means of a phase detector causing either to add pulses from a local oscillator or to inhibit velocity pulses so as to compensate for a phase error in either direction. Alignment is also provided within 60.degree. initially by presetting the ramp counting in relation to a digital representation of sine 60.degree. time intervals over a fundamental cycle.

Abstract: In accordance with the present invention, a single line-frequency sync signal is used to derive cosine-crossover type gating angle reference waves, each with additional phase shifting accounting for phase shifts introduced by the system, such as the power transformers associated with the several thyristors in the sequence. A common variable voltage control signal and comparator are used to apply the various gating signals to the thyristor multiplexer and driver circuits. A plurality of switches controlled by the firing logic circuit establishes the order of selection between the cosine reference waves to be generated.

Abstract: SCR devices replace the usual diodes of the rectifier bridge section of a wound-rotor slip-recovery system motor drive, and by selection of the retardation angle of the SCR's between either zero or close to 180.degree., two-quadrant operation is made possible, which includes reverse torque and reverse rotation, while controlling the retardation angle of the power line bridge of SCR's.

Abstract: SCR devices replace the usual diodes of the rectifier bridge section of a wound-rotor slip-recovery system motor drive. By controlling the retardation angle of the SCR devices while controlling the line bridge for acceleration from zero speed to normal speed, the rating of the overall system is reduced. By removing the gating signal of the SCR's while operating at a retardation angle in the range between zero and 90.degree., operation is immediately brought to a stop in case of an emergency.

Abstract: From a plurality of parallel channels of communication, each including a voltage-to-frequency (V/F) converter, a central clock synchronously timed for each channel, the derivation of a train of pulses having a number of pulses representative of the magnitude of an analog signal inputted to the V/F converter. The central clock also times the multiplexing at the measuring point of either the analog input signal or a bias voltage for calibration or a voltage reference for scaling. The central processor receives the counts from each train of pulses, combines them and threats them to provide a corrected count in each channel separately. Clocking and pulsing are effected through an isolation transformer associated with each channel, to and from the central processor.

Abstract: In a transformer-rectifier converter system, at least one inductance is inserted in the commutation path of two adjacent diode or thyristor devices in a cluster of three devices related to a common DC polarity pole, the reactance due to such inductance being sufficient to lengthen the commutation overlap thereby to minimize AC line harmonics. The invention is applicable to AC/DC as well as to DC/AC conversion.

Abstract: All line control is performed with a power demand control system to bring about ideal rate before the end of a demand period. Demand error is modified so as to project the demand toward a definite point on the ideal rate curve, then to follow the ideal rate toward the target. Correction at a chosen point in time takes into account a possible duration from ideal rate consumption by either choosing the ideal rate short of the target or by pointing exactly to the target. All lines are individually controlled by tap changing with variable deadband and hysteresis, and tap moves are estimated on the basis of individual wattage and amperage changes in a previous control cycle. The minimum between necessary tap moves and the tap moves possible within an upper and a lower limit in the cell line amperage is used for control. The system allows safe settings by the operator and establishes passwords to communicate with the computer system when protected steps are to be dealt with, by the engineer, for instance.

Abstract: In a thyristor-controlled converter system the non-canonical harmonics are minimized by active filtering through control of the firing angle of the thyristors in accordance with the undesired harmonic component.

Abstract: In a steam generator an ultrasonic probe is used to measure the accumulation of sludge between the tubes. A ribbon-like probe carrier is fed into the vessel and deflected by a carriage placed in alignment with a lane of tubes at 90.degree., the probe head being advanced in the lane to measure vertically and sideways the distance to the surface of the sludge. The probe carrier consists of two steel tapes held face-to-face by a plastic tube which has been heat shrunk. The conductors for the transducers are contained in the space between concave tapes. An adaptor mounted at the end of the probe carrier is amovably connected to the probe head. Probe head, adaptor and probe carrier are sealed so that measurement can be conducted inside the steam generator supposedly filled with water.

Abstract: Net power consumed by one or more tools, continuously or intermittently is totalized and compared with a predetermined energy limit characterizing the life expectancy of a tool for optimum and safe use on a machine tool. Digital and computer techniques are used in order to keep track of the usage of the various tools within their respective life expectancies.

Abstract: From a plurality of parallel channels of communication, each including a voltage-to-frequency (V/F) converter, a central clock synchronously timed for each channel, the derivation of a train of pulses having a number of pulses representative of the magnitude of an analog signal inputted to the V/F converter. The central clock also times the multiplexing at the measuring point of either the analog input signal or a bias voltage for calibration or a voltage reference for scaling. The central processor receives the counts from each train of pulses, combines them and threats them to provide a corrected count in each channel separately. Clocking and pulsing are effected through an isolation transformer associated with each channel, to and from the central processor.

Abstract: Method and apparatus is described for interacting bulk acoustic waves with an optical waveguide on a common substrate to switch, modulate or deflect guided light at a very high speed. A direct application lies in a monolithic optical analog-to-digital converter. To this effect, a plurality of transducer elements regularly spaced in an array across the optical waveguide are controlled with constant or variable phase shift along a slope, thus causing deflection of the guided light in a fashion analog to phased-array radar technique. A fully integrated monolithic device is constructed combining the bulk acoustic wave generating and optical waveguide functions.