Abstract: A capacity control algorithm for a multiple compressor liquid chiller system is provided wherein the speed and number of compressors in operation are controlled in order to obtain a leaving liquid temperature setpoint. In response to an increase in the load in the chiller system, the algorithm determines if a compressor should be started and adjusts the operating speed of all operating compressors when an additional compressor is started. In response to a decrease in the load in the chiller system with multiple compressors operating, the algorithm determines if a compressor should be de-energized and adjusts the operating speed of all remaining operating compressors when a compressor is de-energized.

Abstract: A variable speed drive with a boost converter is provided for a chiller system driven by an induction motor. The boost converter can be a diode or thyristor rectifier followed by a boost DC/DC converter or a three-phase pulse width modulated boost converter. The boost converter provides a boosted voltage to the DC link, which results in a boosted voltage being applied to the induction motor by the inverter of the variable speed drive.

Abstract: A variable speed drive is provided having a converter to convert an AC voltage to a DC voltage, a DC link to filter and store energy from the converter, and a plurality of inverters, wherein each inverter is configured to convert a DC voltage to an AC voltage to power a corresponding load connected to the inverter The converter is electrically connected to an AC power source, the DC link is electrically connected to the converter, and the plurality of inverters are electrically connected in parallel to the DC link. Each inverter of the plurality of inverters is configured to operate substantially independently of other inverters of the plurality of inverters.

Abstract: A controller controls operation of a HVAC&R device, bringing the temperature inside a structure from a first temperature to a second temperature at a predetermined time each day. Sensors sense the temperature both inside and outside the structure. A recovery time is calculated based upon a previously calculated air treatment rate of temperature recovery for the HVAC&R device to drive the temperature of the structure through a temperature change, the recovery time calculation being obtained by multiplying the difference between the sensed temperature inside the structure and the second temperature by the previously calculated air treatment rate. A correction factor is calculated based upon a relationship between the sensed outside temperature and a previously sensed outside temperature, the correction factor being added to obtain a corrected recovery time. The HVAC&R device is initiated at a time defined by the predetermined time subtracted from the corrected recovery time.

Abstract: Method and apparatus for the production of a plurality of uniform expansions of a tube in a plurality of tube supports simultaneously. A plurality of tubes are expanded in apertures of tube supports in a repetitive manner, each tube being expanded into the plurality of tube supports simultaneously. The tube expander assembly, when positioned such that each bladder is centered on each land of the tube support surrounding the tube, will precisely control the degree (magnitude) of expansion of each tube against the tube support aperture by controlling the amount of applied hydraulic pressure applied to expandable bladders. The method and apparatus can also be used to expand a tube into the apertures of the tube sheet. This operation can be accomplished without removing the tube expander assembly from the tube. Ideally, the operation is accomplished simultaneously, but may be accomplished in sequential pressurizations.

Abstract: A variable speed drive with a converter that is controllable to precharge a DC link is provided. The variable speed drive also includes an inverter. The converter converts a fixed line frequency, fixed line voltage AC power from an AC power source into DC power. The DC link filters the DC power from the converter. Finally, the inverter is connected in parallel with the DC link and converts the DC power from the DC link into a variable frequency, variable voltage AC power. The converter includes a plurality of pairs of power switches, wherein each pair of power switches includes a reverse blocking power switch connected in anti-parallel to another reverse blocking power switch.

Abstract: A motor mount constructed from a single piece of sheet metal. The motor mount contains a band portion and at least three leg portions. The band portion clamps around a motor and the leg portions radiate from the band portion. The leg portions secure the motor to a housing.

Abstract: A variable speed drive (VSD) having a rectifier, an inverter, an inverter modulator, an inverter controller, and a control loop, for controlling a motor load, wherein the control loop reduces an amount of power transferred to the inverter during a voltage sag. The control loop may include a reference generator, a filter, a regulator, and a ride-through corrective algorithm. A method for controlling a VSD to improve voltage sag ride-through by monitoring a voltage applied to the VSD, generating a control signal representative of losses in a motor load when a voltage sag is detected in the voltage applied to the VSD and applying less power to the load of the inverter.

Abstract: A system and associated method for protecting during a shutdown a turbine having a turbine shaft and a compressor driven by the turbine shaft. The system include a first lubrication system, a second lubrication system, and a control system. The first lubrication system is configured to provide lubrication to the compressor. The second lubrication system is configured to provide lubrication to the turbine. The control system monitors the rotation of the turbine shaft in response to a shutdown request and causes the first and second lubrication systems to provide lubrication to the turbine and compressor until and after the turbine shaft stops rotating. The control system causes the first lubrication system to provide lubrication for a first predetermined period of time after the turbine shaft stops rotating. The control system causes the second lubrication system provides lubrication for a second predetermined period of time after the turbine shaft stops rotating.

Abstract: A heat exchanger unit comprises a plurality of heat exchangers of a construction in which a number of tubes are mounted on mounting plates, which additionally serve as manifolds, in a manner such that the tubes maintained in spaced relation while being twisted such that their axes conform to parts of helices.

Abstract: An electrical control means useful in systems wherein a motor, such as a blower motor for an air handling unit, must be run at different speed levels and wherein low voltage power must simultaneously be supplied to another part of the system such as a condenser unit. The invention combines auto-transformer and transformer technologies into a single motor control unit. Wiring to the auto-transformer portion of the unit is arranged in such manner that it may be readily field changed to accommodate the various line voltage and frequency levels encountered worldwide. Thus, a signle standardized unit allows accurate motor speed control and simultaneous low voltage power supply without motor overheating or instability under various line voltage and frequency conditions encountered throughout the world.