Abstract: A method is provided for determining a shorted thyristor cell in a bridge that supplies a load from a source, the bridge including a plurality of the thyristor cells. The method includes the step of sequentially gating each of the cells to a conducting state, so that only one cell is gated at one time; providing at least one current transformer in the bridge; generating a current flow that passes through the bridge including the one cell that is gated; observing current in the at least one current transformer to determine a short in one of the cells the that is not gated; and determining a shorted cell based on the step of observing current in the at least one current transformer.

Abstract: A compiler and compiling method providing modification of a value of a variable at run-time of a computer program wherein additional space in memory is allocated for variable modification parameters, assembly or object code is added upon compilation of the computer program, the added code being dependent on the variable modification parameters, and the value of the variable is modified at run time based on the added code and at least one of the variable modification parameters such that the value of the variable at run time is set to be equivalent to at least one of a fault value, a value multiplied by a predetermined gain and a value offset from the value of the variable or remains unchanged (unscaled) if so desired. The application of the compiler functionality or method is preferably controllable by a software switch for individual and/or all variables.

Abstract: A configuration of a thyristor stack is provided. The stack includes thyristors, electrically conductive bars, and reactors that are mounted around the electrically conductive. Heat sinks may be included in the thyristor stack to assist in heat dissipation, although they may not be necessary. A method for constructing a thyristor stack is also provided.

Abstract: The invention provides a diagnostic method and system for monitoring controller performance. The diagnostic system includes a tool and a controller. The tool includes a user interface that displays at least one operational status command, such that a user may select the operational status command. A controller has an operation status. The operational status command of the tool queries the operation status of the controller. As a result, the controller generates at least one operational status response. A communications path for transmission of the at least one operational status command from the tool to the controller and the at least one operational status response from the controller to the tool is provided. The user interface displays the operational status response of the controller.

Abstract: A system and method determine the parameters of a field of a DC motor. The method comprises obtaining parameters of the DC motor; and performing an iterative processing loop, the iterative processing loop being performed n times. The iterative processing loop includes regulating field current based on the parameters of the DC motor, and calculating a field resistance from a field voltage and the field current measured during the regulating of the field current; operating in a closed loop mode to determine a first field firing angle and a second field firing angle; operating in an open loop mode to determine a first time constant and a second time constant based on applying the first field firing angle and the second field firing angle; and determining at least one parameter of the field of the DC motor based on the first time constant, the second time constant, and the calculated field resistance.

Abstract: Circuits and methods for protecting thyristors in a bridge configuration are provided. A circuit comprises a line reactor in series with the input of the bridge and the input of the diametric cell, two leg reactors each in series with a respective leg and an output of the diametric cell. Two snubber circuits in parallel with the two thyristors that comprise the diametric cell may also be used to protect the thyristors.

Abstract: Roll gap control is provided using a first roll position detector that detects a first position of a first roll, a second roll position detector that detects a first position of a second roll and a third roll position detector that detects a first position of the third roll. A processor determines a second position of the first roll based on the first position of the second roll and the first position of the third roll.

Abstract: A method and apparatus for controlling flux in an induction motor. During initial start of an induction motor drive the motor flux has to be charged up. The method provides time optimal flux forcing under limited inverter ampere capability. Command stator flux and current are generated and coordinated through a motor flux model. Charging of the motor flux and flux current are accelerated up to nominal operating values in coordinated manner.

Abstract: A system and method for improving transient speed response of electric motors includes a comparator that determines a difference between a current reference and an adjusted current reference generated by the electric motor drive system, and an integrator the receives and integrates the difference between the current reference and the adjusted current reference over time to yield total accumulated lost current-seconds, and outputs at least a portion of the integrated difference between the current reference and the adjusted current reference as current-seconds to be added to the current reference. The present invention keeps track of the total accumulated loss-seconds due to current rate limitations, and restores the total accumulated lost current-seconds to the system when current becomes available.

Abstract: The invention provides a load measurement in a crane hoist system. A parameter adaptation process uses a model of the system in order to measure the lifted load. A controller monitors hoist speed and hoist torque feedbacks that are input into the model and processed using a filter, as well as a previously determined load value. The model adapts automatically to determine the weight of the lifted load.

Abstract: A method and relay for magnetizing inrush restraint in protective relays for power transformers. The method utilizes the phase angle relation between the fundamental component and the second harmonic in addition to the magnitude ratio. This is accomplished by calculating and utilizing the complex second harmonic ratio. The specially shaped operating characteristic for the complex second harmonic ratio is made dynamic providing for better security without jeopardizing dependability of the transformer protective relay.

Abstract: A protective relay, system, and relay operation method which allows logic functions to be distributed amongst multiple protective relays associated with a power distribution system. The protective relays include communications ports for exchanging messages over a peer-to-peer communications network, and include programmable logic. Each protective relay receives logic operands contained in the messages from remote protective relays, executes logic equations using the received operands, provides protective control if needed, and outputs operands to other protective relays.

Abstract: A procedure and method for eliciting expert information on process capability and thereafter manipulating the elicited information in such a manner that it can effectively be used in a process capability database that is operating in a six sigma regime. The manipulation preferably includes converting the expert elicited information from a tolerance-type metric to a short term standard deviation (or sigma) metric, whereby the result of the manipulation is used to populate directly a process capability database and, as appropriate, thereby augment, replace or modulate the data already stored therein.

Abstract: A connection assembly for facilitating connection between a terminal block and a module containing protective relay circuitry. The assembly includes a keycode plate molded to align with and fit over terminal block connection elements extending through openings provided in the keycode plate. The assembly also includes one or more keycode elements fitting into keycode element reception areas provided in the keycode plate, and a module cover having pre-existing slots located and dimensioned so as to align with and receive corresponding keycode elements. The assembly substantially ensures that the correct module is connected to a correct terminal block and substantially prevents an incorrect module from being connected to an incorrect terminal block.

Abstract: A circuit is provided for use in a synchronous generator excitation system. The circuit comprises a three-phase bridge having six legs. The bridge is connected with an AC power supply. A thyristor is provided in each of the six legs, wherein the thyristors provide a path for a device current. A free wheeling diode functions as a de-excitation means connected in parallel with the three-phase bridge. The free wheeling diode provides a discharge path for a field current.

Abstract: An active snubber circuit having a controllable dV/dt. The circuit includes a power device and surface mount components including a resistor having a value selectable to control the dV/dt. The use of surface mount components achieves a low profile, small size circuit that can advantageously be used to eliminate noise generated by contact arcing, to dissipate arc energy while clamping to a predetermined voltage value, and in power conversion applications to provide a desirable dV/dt, among other applications.

Abstract: The flux producing current limit of the motor control is adjusted to control the vibration of a motor. The flux producing current may be profiled in relation to the speed of the motor to compensate for excessive motor vibration.