Abstract: A cooling system for an equipment closet in a building has a direct expansion cooling circuit. The cooling system has two basic modes of operation. A first mode where the direct expansion cooling circuit is off and transfer air from an area of the building outside the equipment closet is used to cool the interior of the equipment closet without any cooling provided by the direct expansion cooling circuit and a second mode where the direct expansion cooling circuit is on and provides direct expansion cooling that is used to cool the interior of the equipment closet.

Abstract: A modular data center is disclosed. The modular data center may have a plurality of unit structures arranged generally parallel to one another. A plurality of supports may be used for supporting the unit structures elevationally above a floor, and wherein adjacent ones of the unit structures form hot aisles therebetween through which hot air generated from data center components may be channeled. Each unit structure may form an elongated structure having a frame structure, a roof panel supported by the frame structure, and a ceiling panel. The unit structures may be used to channel cold air to the data center components and hot air from the hot aisles out from the unit structures.

Abstract: A system is disclosed for monitoring an electrolyte level in a battery cell and generating an indication of a fault condition when the electrolyte level drops below a predetermined acceptable level. The system may make use of a controller, an ultrasonic transmit circuit for transmitting an ultrasonic signal into an interior area of the battery cell, and an ultrasonic receive circuit for receiving the ultrasonic signal after it has been reflected from the interior area of the battery cell. The controller may use the reflected ultrasonic signal and a predetermined calibration signal representing the predetermined acceptable level of the electrolyte to determine when the electrolyte level has dropped below the predetermined acceptable level.

Abstract: A UPS includes an input that receives first power from a utility source to power a load and receives second power from the utility source. The load is separate from the UPS. An inverter receives when in a first mode, the first and second power and when in a second mode, the second power and not the first power. The second power is used to power the inverter. A bypass circuit is connected to the input and bypasses the inverter to supply the first power to an output of the UPS when operating in the second mode. A control module detects a voltage at the output of the UPS, integrates the voltage to generate a first sum, and subsequent to completing a transition between the first and second modes, adjusts an output voltage of the inverter based on the first sum to balance the voltage of the UPS.

Abstract: A system is disclosed for detecting if a remote device is associated with a power supply. The system may have a controller having machine readable, non-transitory executable code running thereon for varying a characteristic of a signal being applied to the power supply. The controller further may be configured to compare a measurement obtained from a measurement subsystem relating to a measured signal present at the remote device. The controller may also be configured to make a comparison between the signal being applied to the power supply and the measured signal obtained at the remote device, and to determine whether the remote device is electrically associated with the power supply.

Abstract: A method is provided for operating a static transfer switch to eliminate transformer inrush current in the presence of residual flux. The method includes: detecting an interrupt of electric power at an output terminal of the static transfer switch; controlling amplitude of voltage at the output terminal using phase fired control of one or more silicon controlled rectifiers interposed between a voltage source and the output terminal, where the amplitude of voltage is set at a value less than a peak value of the sinusoidal waveform; and increasing the amplitude of voltage at the output terminal incrementally until the amplitude reaches a peak value.

Abstract: A pumped refrigerant cooling system having cooling units with associated pumping units for providing working fluid to the cooling unit to enable cooling of a space. The pumped refrigerant cooling system also includes a redundant pumping unit which is activated when a primary pumping unit associated with a cooling unit becomes inactive. The primary pumping unit is deactivated in favor of the redundant pumping unit. Once the primary pumping unit is placed in a condition suitable for reactivation, the redundant pumping unit is deactivated, and the primary pumping unit is reactivated.

Abstract: A microchannel heat exchanger (100) with improvement of dirt-resisting and anti-blocking is disclosed. The microchannel heat exchanger (100) includes at least two heat exchanger units (101, 102) vertically arranged in parallel with the top one being a first heat exchanger unit (101) and the bottom one being a second heat exchanger unit (102). Every heat exchanger unit (101, 102) includes: a first heat tube (103) and a second heat tube (104) oppositely arranged in the horizontal direction; and multiple flat tubes (105) extending between the first and second heat tubes (103, 104) and having both ends communicated with the first and second heat tubes (103, 104). The microchannel heat exchanger (100) also includes multiple fins (109) each arranged between and in contact with the neighboring flat tubes (105) of the same heat exchanger unit and extending from the first heat exchanger unit (101) to the second heat exchanger unit (102).

Abstract: A method including determining whether an OFF criterion is satisfied for a lag compressor of a tandem set of scroll compressors. The tandem set of scroll compressors includes a lead compressor. The method further includes: initiating at least one process when the OFF criterion is satisfied; and maintaining the lag compressor in an ON state for a predetermined period subsequent to the OFF criterion being satisfied. The at least one process includes at least one of: operating the lead compressor at a maximum level; overriding a motor overload protection method, wherein the motor overload protection method protects motors of the lead compressor and the lag compressor; and overriding a proportional integral derivative (PID) method to reduce a speed of a condenser fan. The PID method controls the speed of the condenser fan. A system including the lag compressor module and the lead compressor module.

Abstract: A method includes determining a pressure difference across a scroll compressor of a cooling system. The pressure difference is compared to a minimum differential pressure value. Pressure differences across the scroll compressor that are less than the minimum differential pressure value are associated with unloading the scroll compressor. Parameters including a pressure set point value and an absolute minimum pressure value are increased when the pressure difference is less than the minimum differential pressure value. Subsequent to the increasing of the parameters, the parameters are decreased when the pressure difference is greater than a sum of the minimum differential pressure value and a hysteresis value.

Abstract: A multiple UPS system includes a plurality of multi-module UPS subsystems coupled to a power tie cabinet, each multi-module UPS subsystem having a plurality of UPS modules. The power tie cabinet includes one or more controllers, collectively referred to as PTC (power tie cabinet) controls. The PTC controls periodically determine a power error message for each of the multi-module UPS subsystems and pass it to the respective multi-module UPS subsystem. A controller of the multi-module UPS subsystem uses the power error message to determine error data that is provided to a power average control loop used in control of power sharing among the UPS modules of the multi-module UPS subsystem.

Abstract: A method is provided for detecting a failure of a rectifier or a rectifier source in context of an uninterruptible power supply. The method includes: measuring an input current into the rectifier from a primary power source; determining a rate of change in the measured current; determining a current difference between a reference current and the measured current; measuring voltage output by the rectifier; determining a voltage difference between a reference voltage and the measured voltage; and detecting a failure condition of the rectifier as a function of the measured input current, the rate of change in the measured current, the current difference, the measured voltage and the voltage difference. More specifically, a failure condition of the rectifier is identified when the input current is decreasing and the rate of change in the measured current is decreasing and the current difference is increasing and the voltage difference is increasing.

Abstract: A multiple UPS system has a plurality of UPS subsystems with a separate UPS data communications bus coupling a controller of each UPS subsystem to an associated controller of an associated tie cabinet. The multiple UPS system further includes a data communications tie bus that couples the controllers of the tie cabinets to each other. The controllers of the tie cabinets arbitrate power line based coordinating signals between the UPS buses without the use of auxiliary signals.

Abstract: A system and method is disclosed for analyzing a set of collected raw data point values and determining which one or ones of the values are erroneous data values. In one implementation of the method specific ones of the values are examined to determine if they are outliers, and if so they are removed from the data set. At least two other ones of the values obtained at points in time prior to a given one of the values are examined. Weights may be assigned to the at least two other values, and the weights used to help generate a predicted data point value. The predicted data point value is compared to the given one of the values to determine if the given one of the values is an erroneous value. In this way the integrity of each data point value in the set can be checked.

Abstract: A cooling system has a plurality of separate cooling stages including an upstream cooling stage having an upstream cooling circuit and a downstream cooling stage including a downstream cooling circuit, which are each a direct expansion cooling circuit including a tandem compressor. Each tandem compressor includes a fixed capacity compressor and a variable capacity compressor. A controller controls the fixed capacity compressor and variable capacity compressor of each tandem compressor based on a Call for Cooling, which of a plurality of ranges the Call for Cooling falls within, and whether the Call for Cooling is ramping up or ramping down.

Abstract: A control method is disclosed that involves controlling zero-crossing operation of bridge arms in a UPS, wherein the UPS has a rectifying bridge with first and second switching transistors, a midline bridge arm with third and fourth switching transitors, and an inverter bridge arm with fifth and sixth switching transitors. The midline and rectifying bridge arms are controlled to cross zero synchronously. The inverter bridge arm is controlled to be disconnected during a period before a zero-crossing point of the rectifying bridge arm to a period after the zero-crossing point of the rectifying bridge arm. The periods before and after the zero-crossing point of the rectifying bridge arm are time differences between the zero-crossing points of the inverter bridge arm and the rectifying bridge arm. The influence of asynchronous zero-crossing between the PFC circuit and the inverter circuit on the UPS performance indices may be reduced by using the present control method.

Abstract: A DC offset voltage in an AC input voltage to a transformer and associated saturation current are eliminated by the placement of an anti-parallel diode pair circuit in series between a source of the AC input voltage and a primary winding of the transformer. The anti-parallel diode pair circuit has an input coupled to an output by parallel connected oppositely biased branch diode circuits. Each branch diode circuit has at least one diode where the diode of one such branch diode circuit is biased in one direction and the diode of the other such branch diode circuit is biased in an opposite direction and each branch diode circuit has the same number of diodes as the other branch diode circuit.

Abstract: A cooling door assembly includes a frame and a cooling door coupled to the frame. The cooling door includes multiple heat exchangers. The frame is configured to mount to the back of a server rack or other electronics enclosure in such a manner that the cooling door opens to allow access to the electronics servers within the server rack while maintaining a fluidic connection to an external cooling system. The frame is coupled to the external cooling system and the cooling door includes one or more swivel joints, each configured to provide one or more fluid paths between the cooling door and the frame. The cooling door assembly includes separate and independent fluid paths, where fluid is separately provided to each independent fluid path. Different groups of heat exchangers are coupled to each independent fluid path. In the event of failure of one of the independent fluid paths, the other independent fluid path(s) remain operational.

Abstract: In an aspect, a cooling system has a cooling circuit that includes an evaporator, a condenser, a compressor, a sub-cooler and an expansion device configured in a direct expansion cooling circuit with the sub-cooler coupled in series between an outlet of the condenser and an inlet of the expansion device. The condenser has a micro-channel cooling coil and the sub-cooler has a fin-and-tube cooling coil. In an aspect, the fin-and-tube cooling coil of the sub-cooler has a total hydraulic volume equivalent to the total hydraulic volume of the micro-channel cooling coil of the condenser but the fin-and-tube cooling coil of the sub-cooler has a face area more than two times smaller than a face area of the micro-channel cooling coil of the condenser.

Abstract: A cooling system has a cooling circuit that includes an evaporator disposed in a cabinet, a condenser, a compressor, a liquid/vapor separator tank and a liquid pump. The cooling circuit has a mode wherein the compressor and liquid pump are both on with the liquid pump pumping refrigerant through the evaporator with the refrigerant leaving the evaporator circulated to an inlet of the liquid/vapor separator tank and not to an inlet of the condenser. The cooling circuit also has a pumped refrigerant economizer mode wherein the liquid pump is on and the compressor is off and bypassed with the refrigerant leaving the evaporator circulated to the inlet of the condenser and not to the inlet of the liquid/vapor separator tank.