Abstract: Grouped gating control logic allows for one or more inputs in a group to be active at any given time. Once an input signal in a group is active, all other pulse trains received in the same group can be locked out. Thus, by using a finite state machine to control gate pulses, the noise margin of the gating unit can be regulated and an extra level of protection is available should one of the input gating signals be defective.

Abstract: An apparatus and method for providing a supply of air to cool electrical devices is provided. The apparatus comprises a two fan housings, each containing a number of fans arranged to blow air in a parallel fashion. The exhaust of one housing is connected to the intake of the other housing by a balancing plenum. The apparatus provides a sufficient supply of cooling air when one or more of the fans is inoperable. The device being cooled may be the power bridge of an exciter for a power generation system. A method for providing a supply of air to electrical devices is also provided.

Abstract: A fluid filled transformer including a tank for containing at least primary and secondary windings, a radiator connected to the tank via top and bottom headers, a fluid disposed in the tank, a fluid circulation flow path including passages through the windings, radiator, headers, and at least a portion of the tank, and at least one diagnostic sensor disposed within the fluid circulation flow path for measuring properties of the fluid. By positioning the sensor within the circulation flow path, measured values are more reliable, accurate, and efficiently sensed.

Abstract: A system and method for synchronizing power system data gathered in response to unscheduled power system events such as faults. A plurality of protective devices communicate over a peer-to-peer communication network, and when a first device detects the occurrence of a power system event, the device records cycles of power system data before, after, or surrounding the power system event. The first device informs remote devices via the network of the event and a time tag associated with the event, and the remote devices record synchronized power system data.

Abstract: A method and apparatus for deriving characteristics of a utility signal for synchronizing the output of a motor drive with the utility for a transfer or capture operation. With the drive in idle, the voltage and phase angle of an input to the drive are detected by instrumentation of the drive. The voltage and phase angle of a signal from a utility are detected by instrumentation of the drive at the output of the drive. A phase angle difference and scaling factor are determined to correlate the input signal to the motor drive with the signal at the output of the motor drive. The phase angle difference and scaling factor are stored and subsequently used to derive the signal at the motor due to the utility at the time of the transfer or capture procedure.

Abstract: An apparatus and method for detecting short circuits in a power conversion circuit and a motor drive incorporating the same. The circuit is gated and subsequently a DC bus charger is activated. Charge on the DC bus is measured to indicate a short circuit. After a test iteration, a protective circuit is activated to discharge the DC bus to permit another test iteration to be accomplished quickly.

Abstract: A method and apparatus for transferring an AC machine between non volts per hertz drive and a power supply such as supply mains, or a generator. In a transfer procedure, the motor drive is placed in a quasi-voltage mode prior to transfer to permit the output of the motor drive to be synchronized to the output of the power supply. In capture procedure, the output of the drive is preconditioned based on detected states of the AC machine to synchronize the voltage at the terminals of the AC machine with the output of the drive. During the capture procedure, opening of a contactor is detected by comparing the frequency and/or voltage at the terminals of the AC machine with that of the power supply.

Abstract: A system and method adequately and accurately compares golf scores from two different courses by comparing the relative difficulty of each course played and the relative ability of the players in conjunction with a selected Tournament course, which may be an imaginary or physical course, for determining the winner of a match or game of golf. One method of practicing the present invention uses the USGA Handicap Index, Slope Rating system and Course Rating system to adjust the scores of the players and match the hole handicaps at the two or more courses. Next, the holes of the played courses (including the players' scores) and Tournament course are arranged by hole handicap, hardest to easiest. The final step involves comparing the scores relative to par to determine the score (for stroke play) or the winner of the hole (for match play). This process is repeated for the other holes until all 18 holes have been compared.

Abstract: A method and apparatus for compensating, consistent with variations in cooling conditions, protection and limit functions of a generator. Limits of the capability curve of the generator, including the overexcited region, underexcited region and region limited by stator current heating, are modified in response to changes in coolant pressure or temperature depending on the type of generator being compensated. Feedback signals and setpoints being provided to fixed protection and limit functions are intercepted and modified in accordance with the relationship between generator rated values and generator performance in view of altered coolant conditions. Protection and limit functions are automatically coordinated. As a result, overall generator performance is improved.

Abstract: A protective relay having internal processing circuitry embodied by removable and replaceable modules. Each module includes a main circuit board having common circuitry and also includes removable and replaceable submodules which electrically connect with the main circuit board to perform specific functions. The protective relay can have its functions altered by replacing one or more modules or submodules.

Abstract: A phase lock loop with an improved capture and lock characteristics. A first displacement error signal, a quadrature error signal, and a second displacement error signal arc generated, the second displacement error signal combining the benefits of the first displacement error signal and the quadrature error signal to more closely approximate an ideal error signal and avoid false lock.