Abstract: A signal analyzer for calculating the power consumption and power factor of a three-phase power system driving a motor includes logic that determines whether the analyzer's own input terminals are wired in a proper or inverted manner. To do this, the signal analyzer observes a pattern of zero crossing slope values of the three line-to-line voltages of the three-phase power system and observes a pattern of zero crossing slope values of the current in the three power lines. The analyzer also compares the slope of a voltage signal as the signal passes through zero volts and the sign of a corresponding current signal that exists as the voltage signal crosses zero volts. Based on the observed voltage and current patterns and the voltage-to-current relationships, the analyzer can positively identify which of a plurality of inputs or signal wires are inverted.

Abstract: A signal analyzer for calculating the power consumption and power factor of a three-phase power system driving a motor includes logic that determines whether the analyzer's own input terminals are wired in a proper or inverted manner. To do this, the signal analyzer observes a pattern of zero crossing slope values of the three line-to-line voltages of the three-phase power system and observes a pattern of zero crossing slope values of the current in the three power lines. The analyzer also compares the slope of a voltage signal as the signal passes through zero volts and the sign of a corresponding current signal that exists as the voltage signal crosses zero volts. Based on the observed voltage and current patterns and the voltage-to-current relationships, the analyzer can positively identify which of a plurality of inputs or signal wires are inverted.

Abstract: A motor starter. The motor starter comprises a motor; start, run, shorting and transition contactors operably associated with the motor; and run, start, shorting and transition auxiliary contactors. The transition auxiliary contactor operably controls the operation of a shorting contactor, and the shorting auxiliary operatively controls the operation of the run contactor.

Abstract: A three-phase power system comprising a simple, low cost processor and associated software algorithms for determining true three-phase power factor without having to convert between wye and delta configurations and without having to employ trigonometric calculations or having to measure phase. The processor monitors the source power lines of the three-phase power system by sampling voltage levels and current levels from these power lines and generates data values representative of instantaneous and average three-phase power factor from these levels. The processor uses these data values of power factor and algorithms to detect momentary power loss conditions and surge conditions and takes action to protect the motor and load of the three-phase power system from damage when these conditions occur.

Abstract: A motor starter. The motor starter comprises a motor; start, run, shorting and transition contactors operably associated with the motor; and run, start, shorting and transition auxiliary contactors. The transition auxiliary contactor operably controls the operation of a shorting contactor, and the shorting auxiliary operatively controls the operation of the run contactor.

Abstract: An apparatus for detecting faults in a starter circuit adapted to connect a multi-phase electrical motor to a power supply. The motor has at least one winding per phase, each of which terminates in at least one terminal. The starter circuit includes a plurality of contactors which are energizable to connect the motor windings to the power source. The fault detection apparatus comprises a current sensor for sensing the current flowing through the windings of each phase and responsively producing respective winding current signals. A diagnostic module controllably energizes the contactors, samples for the presence and absence of the winding current signals while different ones of the contactors are energized to detect faults in the contactors, and responsively produces fault signals.

Abstract: An apparatus and method for protecting an induction motor from momentary power loss in a three-phase, alternating current, power supply. The apparatus includes a circuit for detecting when the motor switches from a mode of operation as a motor to a mode of operation as a generator, and a microprocessor connected to the detector to receive the detection of a switch in mode of operation, and for generating a fault disconnect signal in response thereto to initiate disconnecting the motor from the power source. The method includes the steps of detecting when the motor switches from a mode of operation as a motor to a mode of operation as a generator and generating a fault disconnect signal in response thereto to initiate disconnecting the motor from the power source. The apparatus and method provide for robustness of the fault detection data, and for avoiding false detections of momentary power loss.

Abstract: The determination as to whether an operational compressor in a multiple-screw compressor water chiller is fully loaded is made by sending a relatively long duration test pulse to the load solenoid of the compressor. If the compressor is fully loaded, no measurable change in the current drawn by the compressor motor will be measured since no slide valve movement will have occurred and no additional load will have been placed on the compressor. If, however, the compressor is not fully loaded at the time the test pulse is sent, the compressor slide valve will move to load the compressor to an extent such that a reliably measurable change in compressor motor current draw occurs.