AU2008234969A1

AU2008234969A1 - Ventilation system and/or method

Info

Publication number: AU2008234969A1
Application number: AU2008234969A
Authority: AU
Inventors: Robert Lynch; Alan Pettigrew
Original assignee: B & R Enclosures Pty Ltd
Current assignee: B&R ENCLOSURES Pty Ltd
Priority date: 2007-10-25
Filing date: 2008-10-24
Publication date: 2009-05-14

Description

P/00/01 1 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: VENTILATION SYSTEM AND/OR METHOD Applicant: B&R Enclosures Pty Ltd The following statement is a full description of this invention, including the best method of performing it known to me: 1 -2 VENTILATION SYSTEM AND/OR METHOD FIELD OF THE INVENTION 5 The present invention relates to a ventilation system and method for an equipment rack. In a typical application the present invention may be used to manage forced air cooling in an electronic and/or electrical equipment rack, such as a telecommunications equipment rack, a computer equipment rack, or a data storage device equipment rack. 10 BACKGROUND OF THE INVENTION Electrical and electronic equipment such as computer equipment, data storage equipment, telecommunications equipment and the like are often mounted in equipment racks or cabinets. Such equipment racks typically 15 include an assembly of horizontal and vertical metal extrusions that are assembled to form a standard-sized frame. The frame assembly often defines a standard width dimension for the rack (for example, a "19-inch rack") as well as uniformly-spaced attachment points (for example, a standard 40-U rack) to enable installation of equipment items, along the attachment points. Thus, a 20 single rack may house multiple equipment items, with the number and types of equipment items depending on the application. For example, an equipment rack for a computing application may house one or more rack mountable computers, a rack mountable data storage unit, a rack mountable power supply unit, a rack mountable graphics display, and the like. On the other hand, an 25 equipment rack for a data storage application may house multiple rack mountable data storage devices, such as an array of hard disk drives. A standardised rack assembly enables equipment manufacturers to manufacture equipment items as modular components in standard sizes for integration with other equipment items within the rack enclosure. A user can 30 then install modularised equipment items from different manufacturers at different locations within the rack enclosure to "build" an overall system. Each equipment item typically includes a chassis which is normally secured to attachment points on the rack enclosure, and electronics or electrical circuitry or other devices installed within or on the chassis, and a cooling 35 subsystem, such as a cooling fan.

-3 The cooling subsystems may be configured to provide horizontal air flow from the front of the equipment rack enclosure through to the rear of the enclosure through the chassis and across the contents of that chassis so as to remove heat during operation. In addition, for each equipment item having an 5 integrated cooling subsystem, each subsystem usually operates entirely independently of the other cooling subsystems, since each cooling subsystem is a component of a particular equipment item. There is thus no coordination between the different cooling subsystems. Another conventional electronic equipment rack includes a custom-built 10 frame that defines customised dimensions rather than standardised dimensions. Here, a single manufacturer controls the design of the rack by selecting customised dimensions. Using such an approach, the manufacturer may include a single "primary" cooling subsystem for cooling all of the equipment items within the entire equipment rack enclosure. Because the primary cooling 15 subsystem provides ventilation for all of the equipment items, such a cooling system typically uses a higher power motor than individual cooling subsystems installed with equipment items and thus can result in operational inefficiencies. Unfortunately, in systems which include a "primary" cooling subsystem, and although that sub-system may operate in conjunction with the individual 20 cooling subsystems provided with the equipment items, each cooling subsystem, whether that be the "primary" cooling subsystems or the equipment items' cooling systems still operate independently of each other. Thus, there is no coordination between the various cooling subsystems. Thus, irrespective of the type of equipment rack, conventional cooling 25 sub-systems do not typically provided a coordinated approach to controlling the volume and/or distribution of forced air ventilation through the rack, such that the cooling devices have an operational interdependency. Thus, control of the flow of the cooling air through the equipment rack is often quite course and non optimal. In addition, existing cooling sub-systems are unable to respond to 30 changes in the configuration of the equipment rack, such as may be encountered when, for example, an equipment item is replaced with a different type of equipment item or is moved to a different location or position within the equipment rack.

-4 It would be desirable to provide an equipment rack that includes a cooling system which is responsive to changes in the performance or configuration of equipment items are installed in the rack. 5 SUMMARY OF THE INVENTION The present invention provides an equipment rack for housing one or more electrical equipment items, the equipment rack including: a structure for supporting each equipment item in one or more positions in the rack; 10 for each position, one or more sensors for sensing a parameter value attributable to the electrical power demand of each electrical equipment item located at the position, and one or more associated ventilating devices for supplying a ventilating gas; and a controller in communication with each sensor and ventilating device, 15 the controller for receiving and processing each sensed parameter value and controlling the volume and/or temperature of the ventilating gas supplied by each ventilating device according to the sensed parameter value or values for the associated position. An embodiment of the equipment rack senses a parameter value(s) 20 attributable to the electrical power demand of the electrical equipment items located in the rack and translates the sensed value(s) into a cooling requirement. The cooling requirement may be expressed in terms of a requirement to supply a specific amount (for example, a volume) of the ventilating gas to a particular position, or positions, within the equipment rack, 25 or alternatively to provide the ventilating gas at a particular temperature to the particular position, or positions. By sensing and reacting to power demand, it is expected that the present invention may be able to predict and respond to potential "hot spots" before excessive temperatures are observed. 30 Throughout this specification the term "electrical equipment item" denotes any type of electrical or electronic equipment rack mountable equipment that requires a connection to an electrical power source in order to operate. Examples of equipment items include, data storage devices such as an optical disc device (for example, a CD-ROM, a DVD device, a Blu-Ray -5 device), a magnetic storage device (for example, a hard disk drive, or a tape drive), a semiconductor storage device (for example, a flash memory drive); computing equipment such as a rack mountable computer (for example, a rack mountable laptop computer); switching equipment such as circuit breakers, 5 relays, sequence controllers, switch units; power conversion equipment AC to DC power supplies, DC to DC converters, batteries; display equipment such as rack mountable cathode ray tubes, liquid crystal displays (LCD), plasma displays, light emitting diode (LED) displays; telecommunications equipment such as receivers, transmitters, transceivers; computer networking equipment 10 such as data switches, hubs, patch panels and the like. As will be appreciated, special mounting hardware such as telescopic slides, brackets or support rails may be required to mount an equipment item within the equipment rack. Suitable mounting hardware would be within the knowledge of a skilled reader. The structure may include any customised or standard rack structure. 15 For example, in one embodiment, the structure is a 19" rack type structure including a 19" frame for supporting the equipment items. However, it will of course be appreciated that the present invention is applicable to a variety of different structures such as cabinets, and sub-racks. Any suitable sensor may be used to sense the parameter value 20 attributable to the electrical power demand of each electrical equipment item with the actual sensor, or sensor type, depending on the parameter being sensed. In one embodiment, each sensor includes a current sensor for sensing the current supplied to the one or more electrical equipment items located at a respective position so that the sensed parameter value includes a sensed value 25 of electrical current. Suitable current sensors may include a current transformer, a Hall Effect device, or a resistive based sensing circuit. In one embodiment, the sensed current is an instantaneous current. In an alternative embodiment, each sensor includes a power sensor for sensing the electrical power supplied to the one or more electrical equipment 30 items at a respective position so that the sensed parameter value includes a sensed value of electrical current. The sensed power will typically be the instantaneous power. In yet another embodiment, the equipment rack includes additional sensors for sensing additional parameters values which may not be directly -6 attributable to electrical power demand. For example, one or more environmental sensors (such as temperature sensors) may be provided for sensing an environmental parameter at one or more positions located either internally or externally to the equipment rack. In such an embodiment, the 5 sensed values attributable to the electrical power demand and the additional sensed parameter values may be processed so that controlling the volume and/or temperature of the ventilating gas supplied by each ventilating device has a dependency all of the sensed parameters. In one embodiment, the sensed environmental parameters may include, 10 for example, temperature or humidity. Thus, in one embodiment, controlling the volume and/or temperature of the ventilating gas supplied by a ventilating device according to the sensed parameter value or values for a respective position includes determining a fan speed for a variable speed fan associated with the ventilating device according to a sensed value of temperature or 15 humidity. In one embodiment, the sensed temperature may be the air temperature in, or adjacent to, an inlet or an outlet of the equipment rack, such as a vent or a duct. In another embodiment, the sensed temperature may be the temperature of air in a region or space in the vicinity of an equipment item. For example, the 20 sensed temperature may be a sensed temperature of a volume of air at the position at which the equipment item is located. The ventilating device may include a fan-based device which may include one or more variable speed fans. The fans may be of any suitable type, and may include, for example, axial flow fans, radial flow fans, centrifugal fans, 25 or flat pack fans. Alternatively, the ventilating device may include a heat exchanger, or an air conditioning unit. In an embodiment, each ventilating device is housed in a ventilating unit that may include other ventilating devices. Such a ventilating unit may also enclose the controller so that the controller and one or more ventilating devices 30 are collocated. However, it is not essential that the controller and the ventilating device(s) be located in the ventilating unit and, for example, the controller may be a separate device or unit. The equipment rack preferably includes an input device for accepting configuration information from a user. The input device may include, for -.7 example, data communications equipment (such as a terminal) connected to the controller via a suitable communications interface, a touch panel, a key pad, a key board, a mouse, a joystick, a tracker ball or a client computer connected to the controller via a computer network. 5 The controller may accept configuration information for storage in memory on-board the controller. Alternatively, the controller may communicate configuration information to the ventilating unit for storage in memory on-board the ventilating unit with which the configuration information is associated. In an embodiment, the configuration information identifies an association 10 between each position of the equipment rack and one or more respective ventilating devices of a ventilating unit, and/or sensors. The configuration information identifying an association between each position and one or more respective ventilating devices (such as variable speed fans) may be expressed in terms of a weighted numerical value expressing a proportion of the output of 15 the one or more ventilating devices associated with a position. In such an embodiment, a ventilating device could be assigned a weighted numerical value for plural positions. In an embodiment, for each ventilating device, the volume and/or temperature of the ventilating gas is controlled according to the sensed 20 parameter value or values for each position having an identified association with the ventilating unit, to an extent that depends on the associated weighted numerical value for each respective position. The equipment rack may further include a programmed memory programmed with data encoding operating values specifying operating 25 parameters for each of the one or more ventilating devices so that controlling the volume and/or temperature of the ventilating gas supplied by each ventilating device depends upon the specified operating parameters. In such an embodiment, the operating parameters may include one or more of a fan minimum speed, a fan maximum speed, fan spin-up time, fan airflow at 30 minimum speed, fan airflow at maximum speed, and hysteresis. The equipment rack may further include a power outlet module that includes multiple electrical outlets for electrical connection with electrical inputs of the equipment items. In such an embodiment each sensor may be operatively associated with a respective one of the electrical outlets. By way of -8 example, in one embodiment, in which the sensors are current sensors for sensing the instantaneous current demand of an equipment item, one current sensor may be provided for each electrical outlet of the power outlet. In one embodiment, the sensors are integrated with the power outlet module. It will of 5 course though be appreciated that it is not essential that the sensors be integrated. For example, in some embodiments current sensors are located externally to the power outlet module. The power outlet module will typically include an interface for communicating a signal to the controller, or another device, sharing a 10 communications infrastructure (such as a bus) with the power outlet module. The signal may encode the sensed parameter values using a suitable data format and communications interface protocol. The communications interface protocol may be a customised wired or wireless protocol or it may be a standard wired or wireless protocol. Examples 15 of suitable standard wired communications interface protocols include serial protocols such as RS232, RS422, RS-423, and EIA-530. Of course, other forms of wired communications interface protocols may also be used, such as a data packet-based communications protocol such as an IEEE 802 based data communications standard. Examples of suitable wireless communications 20 protocols include Bluetooth, ZigBee, IrDA, Wireless USB, WiFi, HIPERLAN, and WiMAX. In an embodiment, the power outlet module includes a programmable memory which is programmable to store, for each electrical outlet, data encoding an identifier associating the electrical outlet with a position of the 25 equipment rack. Alternatively, the memory may be programmable to store, for each electrical outlet, data encoding an identifier identifying the position of the equipment item connected to the electrical outlet. In either case, the signal encoding the sensed parameter values also encodes, for each sensed parameter value, the identifier for the position associated with each sensed 30 parameter value, in other words, either the position of the electrical outlet in the equipment rack or the position of the equipment item connected to the electrical outlet. The present invention also provides a ventilating unit for an equipment rack, the ventilating unit including: -9 a housing for housing one or more variable speed fans; a microprocessor with an associated programmable memory containing a set of program instructions that are executable by the microprocessor; and a fan control circuit in communication with the microprocessor and the 5 one or more fans; and a communications interface; wherein the programmable memory stores, for each fan, data encoding a unique identifier so that each of the one or more fans has an associated unique identifier, and wherein the communications interface is configured to receive a 10 signal containing control data from a controller, the control data being addressed to one or more of the fans and being decodable by the microprocessor under the control of the program instructions to cause the fan control circuit to vary the speed of the fans addressed by the control data according to the associated control data. 15 In an embodiment, the programmable memory contains data encoding operating values specifying operating parameters for each of the one or more fans, and wherein, the operating parameters include one or more of a fan minimum speed, a fan maximum speed, fan spin-up time, fan airflow at minimum speed, fan airflow at maximum speed, and hysteresis. 20 In an embodiment, execution of the program instruction causes the microprocessor to communicate the data encoding operating values to a controller via the communications interface. The data encoding operating values may be communicated periodically automatically. Alternatively, the data encoding operating values may be communicated in response to a request from 25 the controller. The control data may include data encoding sensor information from one or more sensors sensing a parameter value attributable to electrical power demand of an equipment item, in which case execution of a program instruction by the microprocessor may cause the microprocessor to process each sensed 30 parameter value and control the volume of ventilating gas supplied by each fan according to the sensed parameter value. The present invention also provides a power outlet module including one or more electrical outlets for connecting to an equipment item, the power outlet module including: - 10 a housing for housing the one or more electrical outlets; for each electrical outlet, a sensor for sensing a parameter value attributable to the electrical power demand of an equipment item connected to the electrical outlet, each sensor being associated with a respective one of the 5 electrical outlets; and a microprocessor with an associated programmable memory containing a set of program instructions that are executable by the microprocessor and data encoding a unique identifier for each electrical outlet; and a communications interface; 10 wherein execution of the program instructions causes the microprocessor to process sensed parameters values and output from the communications interface a signal containing data derived from the sensed parameters values together with the unique identifier for the electrical outlet associated with the sensed parameter. 15 The unique identifier for each electrical outlet may be in the form of information identifying the position in an equipment rack of an equipment item connected to the power outlet. Hence, it is preferred that each position in the equipment rack has an associated identifier, such as a numerical, alphabetical, or alphanumerical identifier. 20 The present invention also provides a system for monitoring and controlling the ventilation of one or more equipment racks, each equipment rack housing one or more electrical equipment items, the system including: one or more sensor for sensing a parameter value attributable to the electrical power demand of an equipment item located in a position of an 25 equipment rack; for each equipment rack, a ventilating unit including one or more variable output ventilation devices configured to supply a ventilating gas to one or more positions in the equipment rack; and a controller in communication with each sensor and ventilating device, 30 the controller for receiving and processing each sensed parameter value and controlling the volume and/or temperature of the ventilating gas supplied by each ventilating device so that, for each position, the volume and/or temperature of the ventilating gas is controlled according to the sensed parameter value or values for that position.

- 11 In an embodiment, the system further includes a server computer in data communication with at least one controller of an equipment rack; and a client computer operatively connected to the server computer, the client computer being operable by a user to display status data received from a selected one or 5 more of the controllers in data communication with the server computer. The status data may include one or more of sensed environmental data; sensed electrical power data; and operational data. The present invention also provides a method of regulating the temperature of an equipment rack housing one or more electrical equipment 10 items in different positions of the equipment rack, the method including: for each position sensing a parameter value attributable to the electrical power demand of each equipment item located in the equipment rack; processing each sensed parameter value; controlling the volume and/or temperature of a ventilating gas supplied by 15 a ventilating unit including one or more ventilating devices associated with one or more of the positions so that, for each position, the volume and/or temperature of the ventilating gas provided by the ventilation device(s) is controlled according to the sensed parameter value or values for the associated position. 20 A particular advantage of embodiments of the present invention is that they may provide a ventilating system or components for an equipment rack that is able to direct the necessary ventilating gas to an equipment item based on the conversion of data concerning the power consumption of that item into a cooling requirement. In other words, embodiments of the present invention may 25 be able to vary the strength or focus of cooling air on-the-fly and in response to the cooling requirement of specific equipments items within the equipment rack. Such an approach is expected to offer advantages over prior art equipment rack ventilations systems which typically do not include a feedback path in the ventilating system which adjust the operation of the ventilation responsive 30 depending on power consumption.

-12 BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in relation to various embodiments illustrated in the accompanying drawings. However, it must be appreciated that the following description is not to limit the generality of the above description. 5 In the drawings: Figure 1 is a block diagram of a ventilating system according to an embodiment of the present invention; Figure 2 is a block diagram shown a communications interface for use with an embodiment of the system shown in Figure 1; 10 Figure 3 shows a block diagram of a ventilating system according to another embodiment of the present invention; Figure 3A is an interface diagram for the ventilating system shown in Figure 3; Figure 4 shows a top view of a side-by-side arrangement of equipment 15 racks illustrating air flow paths for the ventilating system shown in Figure 3; Figure 5 is a partial front close up perspective view of an enclosure suitable for a ventilating unit for use with an embodiment of the present invention; Figure 6 is a partial rear perspective view of a ventilating unit for use with 20 an embodiment of the present invention; Figure 7 is a partial front perspective view of a ventilating unit for use with an embodiment of the present invention; and Figure 8 is a flow diagram of an example mode switching scheme for an embodiment of the present invention. 25 DETAILED DESCRIPTION OF THE INVENTION Turning now to Figure 1 there is shown a block diagram for a system 100 for monitoring and controlling ventilation of one or more equipment racks 102. In the illustrated embodiment each equipment rack 102 houses one or more 30 electrical equipment items 104 in different positions (which, in this example, are labelled as position "1" to position "6"). The equipment rack 102 may house any type of electrical or electronic equipment items with the actual items typically depending on a specific application associated with the rack such as, for example, industrial computing, -13 data storage, scientific computing, computer simulation, telecommunications, networking, or the like. Thus, the equipment items 104 will typically include a combination of rack mountable components such as, computers, data storage devices, power conversion products, switch gear and relays, display equipment, 5 display panels (such as LED display panels), audio equipment, video equipment, interface equipment (such as interface panels and interface logic), and the like. The equipment items 104 may require brackets or slides in order to support mounting within the equipment rack 102. The equipment rack 102 may be, for example, a 19" standard equipment rack, or it may be customised 10 or compliant with another standard. In this respect, the term "equipment rack" denotes any cabinet, rack, housing, desk, framework, or other enclosure that provides multiple positions (usually in the form of shelves or bays) in which equipment items may be located. The system 100 also includes one or more sensors 106 for sensing a 15 parameter value attributable to the electrical power demand of an equipment item 104 located in a position of an equipment rack 102. In the present example, the sensors 106 include current sensors configured to sense the instantaneous current demand of a respective equipment item 104. A sensor 106 may be arranged in-line with an electrical circuit that 20 provides electrical power to a respective equipment item 102. Alternatively, a sensor 106 may be integrated within a module, such as a mullti-outlet power outlet module or a circuit breaker or the like. In an embodiment in which the sensors 106 are integrated within a mullti outlet power outlet module, the module may include multiple electrical outlets 25 for connecting to the input power leads of the equipment items 104. In such an embodiment, each sensor 106 may sense a parameter value attributable to the electrical power demand of an equipment item 104 connected to an electrical outlet, and thus has an operative association with a respective one of the power outlets. 30 The equipment rack 102 includes an associated ventilating unit 108 that includes one or more variable output ventilation devices 110. The ventilating unit 108 may be a module that is attachable to the equipment rack 102, or it may be integrated with the structure of the equipment rack 102 structure.

- 14 In the embodiment illustrated in Figure 1, each ventilating device 110 is an axial flow fan having a variable output in the form of a variable speed. It will be appreciated that any suitable fan may be used. One example of a suitable fan is a 3-wire 12V Delta fan identified by part number FFB0912EHE. It will of 5 course be appreciated that other types of fans or ventilation devices may be used. For example, in another embodiment the ventilation devices may include heat exchangers. Irrespective of whichever type of ventilation device 110 is used, each ventilating device 110 will be configured to supply a ventilating gas to one or 10 more positions (shown as positions "1'" to "6") in the equipment rack 102. Typically, the ventilating gas will be air which is cooler than the air within the equipment rack 102. It will of course be understood that ventilating gases other than air may be used, such as nitrogen. Although not shown in Figure 1, the ventilating unit 108 may also include, 15 or be in communication with, other sensors, such as temperature and other environmental or security sensors, which are also operatively associated with the ventilating devices 110. An example of an equipment rack 102 that includes temperature sensors will be described in more detail later. As shown in Figure 1, the system 100 also includes a controller 112 in 20 communication with each sensor 106 and the ventilating unit 108 via a suitable communications architecture 114. In the present case, the controller 112 is illustrated as separate to the ventilating unit 108. Such an embodiment is expected to be particularly suited to arrangements that include multiple equipment racks 102 and multiple ventilating units 108. However, in some 25 embodiments, particularly embodiments that include a single equipment rack 102, the controller 112 may be integrated with another device, such as the ventilating unit 108. In the embodiment illustrated in Figure 1, the communications architecture 114 is a multidrop synchronous serial bus, such as an EIA-485 30 communication architecture. Other synchronous serial bus architectures would be known to a skilled reader and may include, for example, 12C, JTAG, SPI, SSC, ESSI, MODBUS and the like. Moreover, although the embodiment illustrated in Figure 1 utilises a multidrop synchronous serial bus for data communication between the controller 112, the ventilating unit 108, and the -15 sensors 106, it is to be appreciated that other types of wired or wireless communications architectures may be used such as, for example, SCSI, IEE802 based (for example, IEEE802.11), Bluetooth, IrDA, ZigBee, IEEE-418 (GPIB), wireless universal serial bus (WUSB), wired USB, IEEE-1394 5 (Firewire), and the like. Of course, if a wireless interface is employed then the controller 112, the sensors 106 and the ventilating unit 108 will include suitable wireless interfaces, such as a suitable wireless transceiver. Additional suitable communication architectures would be well known to a skilled addressee. During operation, the controller 112 receives and processes sensed 10 parameter values from the sensors 106 and controls the volume and/or temperature of the ventilating gas supplied by each ventilation device 110 so that, for each position, the volume and/or temperature of the ventilating gas is controlled according to the sensed parameter value or values for that position. The controller 112 may be any suitable processing device, and may 15 include, for example, a processing unit equipped with a suitable microprocessor (or microcontroller) and an associated program memory programmed with a set of program instructions in the form of a computer program. For example, the controller 112 may be an embedded computing device, such as a VMEbus or PClbus based controller. As will be appreciated, a processing unit may include 20 any suitable type of microprocessor or microcontroller such as, for example, a MIPS, 68k based, PowerPC, x86, PlC, 8051, Z80, Z8 or the like CPU. Alternatively, the controller 112 may include a system on a chip (SoC), application-specific integrated circuit (ASIC), or field-programmable gate array (FPGA), programmed with suitable logic. In yet another embodiment, the 25 controller 112 may include a desktop computer, a hand-held computer, a laptop computer, a notebook computer or the like, programmed with a suitable operating system and application software. In illustrated embodiment, the controller 112 is depicted as a customised product including a microprocessor (not shown), an associated memory (not shown), an output display 116 (such 30 as an LCD display), a power supply (not shown), and an input interface in the form of a keypad 118. To enable communications with the sensors 106 and the ventilating unit 108, the controller 112 includes a suitable communications interface 120. As will be appreciated, the communications interface 120 will be compatible with - 16 the communications architecture 114 and thus may include a wired or wireless communications interface. In the present case, the controller 112 includes plural serial ports for communicating with other devices via the multidrop serial bus architecture. Preferably, each serial port is capable of addressing multiple 5 devices per port. As is shown in Figure 2, the controller 112 may also include additional communications interfaces 200, such as a 10/100 Ethernet port configured to support data communication with other devices, such as client computer 202, via a second communications architecture 204 separate to communications 10 architecture 114. Such an arrangement may permit a user who is remote from the equipment rack 102 (ref. Figure 1) to enter or modify operational parameters of the ventilating unit 108, the controller 112 or the sensors 106. The second communications architecture 204 may support, for example, packet based (for example IP based) data communication, SSL, SNMP, or 15 Telnet data communication. Other types of suitable communication architectures would be well known to a skilled reader. Returning to Figure 1, in the present example, the controller 112 interrogates or receives data from the sensors 106 and processes that data to determine the real-time current (and hence power consumption/heat 20 dissipation) of the, or each, equipment item 104. The controller 112 then communicates a signal to the ventilating unit 108 via the communicatons architecture 114. The signal contains control data addressed to one or more of the ventilating devices 110. The signal is decoded by the microprocessor on board the ventilating unit 108 which then instructs, via a suitable control 25 interface, the ventilating devices 110 to control their speed according to the associated control data. In other words, each ventilating device 110 is individually controlled by the integrated microprocessor or microcontroller based on the processing of the sensed data from the sensors 106, and thus the sensed parameter. 30 Figure 3 shows another embodiment of a system 300 according to the present invention. The embodiment depicted in Figure 3 includes two equipment racks 102-1, 102-2, each of which has an associated ventilating unit 108-1, 108-2.

- 17 In the embodiment illustrated in Figure 3, each equipment rack 108-1, 108-2 includes a pair of multi-outlet power outlet modules 302-L, 302-R. Each module 302-L, 302-R includes plural electrical power outlets and sensors (which in the present example are labelled as Ln and Rn - where Ln and Rn each 5 represent an associated power outlet and sensor). Each power outlet module 302-L, 302-R includes a bank of electrical power outlets. In the present case the power outlet modules 302-L, 302_R are arranged as a "left" bank 302-L and a "right" bank 302-R. Similarly, each ventilating unit 108-1, 108-2 includes two banks ("BANK1", "BANK 2") of 10 ventilating devices 110 which in the present case are arranged in the form of fan tower mounted alongside a respective equipment rack 102-1, 102-2 and which extends along the full height of the equipment rack 102-1, 102-2. In the present case, each power outlet module 302 provides an intelligent power distribution unit in that each power outlet module 302-L, 302-R contains 15 plural switched power outlets (L1 to L8) and supports measurement of output currents of each outlet via the integrated sensors. Furthermore, embodiments of a power outlet module may also support remote or automated switching of individual outlets, staged switching (sequential switching) on start-up/reset or after power failure, field or remote programming via web or command line 20 interface, network addressing (when configured as a master) via a suitable communications interface. As shown in Figure 3 and Figure 3A, each power outlet module 302-L 302-R may also be configured to support data communication with another power outlet module so as to form a master/slave configuration, such as via 25 interface 310. Each power outlet module 302-L, 302R may also provide ports 312 (refer Figure 3A) for sensors and actuators, such as temperature sensors 308. As shown in Figure 4, each ventilating unit 108-1, 108-2 draws air from a cool aisle ("COLD AISLE") and forces it across the front face ("FRONT") of 30 installed equipment items 104 in proportion to the heat generated by that equipment in order maximise the efficiency of through-equipment (front to rear) cooling. It will of course also be appreciated that the ventilating units 108-1, 108-2 may also be configured to enhance side to side cooling. The ventilating devices 110 are shown removed in Figure 5 so as to more clearly detail the - 18 path of the air flow through a ventilating unit 108. Although not shown in Figure 4, barriers, such as brushes, may be fitted between the equipment racks 102 to prevent cold/warm air mixing. Such brushes may isolate cold air to the front of the equipment rack only or to the front and side. Where side cooling is required 5 a full height panel can be installed along the equipment rack side posts which can vent air to specific locations. It is possible that exhaust chimneys may be fitted in the rear section of the equipment rack 102 to extract warm air. In the embodiment illustaretd in Figure 3, each of the ventilating units 108-1, 108-2 contains a microprocessor unit which provides communication 10 with the controller 112, communication with downstream sensors 304, 306, 308, fan control and controller input. In the preset case, each ventilating device is DC powered and independently controlled (on/off, variable speed) by the microprocessor using pulse width modulation (PWM). The ventilating units 108-1, 108-2 may be programmed via the controller 15 112 (or a local terminal) to provide information that relates the physical location of an equipment item connected to a power outlet of the power outlet module 302-L, 302R to the appropriate ventilating device 110-1, 110-2 or combination of ventilating devices 110-1, 110-2 as well as environmental thresholds, and various alarms. 20 Each ventilating unit 108-1, 108-2 may support a number of operating modes depending on the availability of sensor and power consumption data. In operation, the ventilating units 108-1, 108-2 may automatically switch between modes if conditions change, for example, if there is a break in the communication link with the controller 112. 25 In the embodiment illustrated in Figures 5 to 7, each ventilating unit 108 includes an enclosure 500 (refer Figure 5) for housing electronics (not shown) and the ventilating devices 110. In the present case, the ventilating devices 110 (shown as fans) are arranged in banks. It will be appreciated that any suitable number of fans may be used. 30 In the present case, and referring now to Figures 6 and Figure 7, the electronics is located in a housing 600 of the enclosure 500 located behind the fans 110. The housing 600 may have any suitable shape and dimensions for housing the electronics and fans. For example, a 200mm wide enclosure may contain two banks of 12 fans each, and may also provide two PWM ports for a -19 25 th and 26 th fan which can be mounted into equipment rack roofs to exhaust warm air. Alternatively, a 100mm enclosure may contain one column of 12 fans and a single PWM port for the 13 th fan for exhaust air. It is preferred that the exhaust fan(s) be independently powered and will be sized to match the 5 incoming fan capacity. As is shown in Figure 6 and Figure 7, the housing 600 also includes air inlets which can be filtered if required. For example, Texa TX-FIL12XNOA filters which have a 150mm square footprint and require a 125mm square opening may be used. 10 In the present case, each ventilating unit 108 is powered by two +12V PCI-E VGA card power supplies which are located externally. One example of the type of power supply which may be used is the Thermaltake Model W0130. Each power supply unit (PSU) can be fed from independent AC supplies (for redundancy), if available, in the data centre. The PSU's may be mounted into 15 the equipment rack. Referring again to Figure 3, each ventilating unit 108-1, 108-2 has a data communications interface that is compatible with the communications infrastructure 114. Thus, in the present case each ventilating unit 108-1, 108-2 includes a communications interface that is compatible with the same serial bus 20 addressing schema as the controller 112. In the present case, each ventilating unit 108-1, 108-2 is configured to operate in a number of modes depending on the availability of input data, which in this case includes power consumption data and temperature data. One example of a hierarchy of operating modes (listed from "simplest" to 25 "complex") together with the relevant input data is as follows, although it will be appreciated that the following hierarchy and modes are not intended to be limiting: * Open loop: no temperature data or power consumption data (mode "XX"); 30 e XP Open loop: power consumption data, but no temperature data (mode "XP") " TX Closed loop: temperature data, but no power consumption data (mode "TX"); and - 20 * Closed loop: temperature data and power consumption data (mode "TP"). In one embodiment, the ventilating unit 108 will operate in TP mode unless TP mode is disabled, or the ventilating unit 108 "loses" input data, in 5 which case the ventilating unit 108 may revert to a "simpler" mode (in other words, a mode arranged higher that the TP mode in the above list), or the user manually selects a simpler mode. Each of the exemplary modes may require suitable configuration or setup information. In this respect, if a mode has not been properly setup (or if it has been disabled), the ventilating unit 108 will 10 "skip" that mode when switching to a simpler mode. Other "non-operating" modes may also be provided, including, for example: * A manual control mode; * A power failure mode; and " A self test mode(for example, a filter check mode). 15 The "operating modes" set out above will now be desribed in the following examples. Example 1: XX Open Loop - no temperature or power consumption data In XX mode the ventilating unit 108 does not utlise temperature data or power data. Thus, in XX mode, for example, the fans of the ventilating unit 102 20 may be set to operate at a "common fan speed" (in ohther words, all fans operate at the same speed) selected from 0% to 100% of a threshold speed value or, alternatively, an individual fan speed (in other word, fan speeds are individually set) may be selected from 0% to 100% of the threshold speed value. 25 Example 2: XP Open Loop - no temperature data but power consumption data In XP mode the ventilating unit 108 may function according to the following logic: 1. Aggregated power Using "aggregated power" logic, the ventilating unit 108 aggregates the total 30 power consumed within the equipment rack (as sensed by a power outlet module) and then sets a common speed for all fans. For example, the common fan speed may be based on, or may be calculated according to: * Total power consumed within the equipement rack; -21 * Inlet air temperature; and " Maximum allowable temperature. 2. Individual power Using "individual power" logic, the ventilating unit 108 may set individual fan 5 speeds based on: " Proximity tables linking power outlet module outlets to equipment rack positions; * Fan overlap tables (in other words, tables linking fan influence on directly adjacent and non-adjacent equipment rack positions); 10 e Power outlet module power consumption; " Inlet air temperature; and " Maximum allowable temperature. Thus, in XP mode, the following information may be required: * An "aggregated power" or "individual power" logic selection; 15 e Fan overlap tables; " Maximum allowable temperature; and * Power outlet module to equipment rack position proximity tables. Example 3: TX Closed Loop - temperature data but no power consumption data TX mode may be engaged where the ventilating unit 108 is installed so 20 as to operate in a stand-alone configuration (with temperature sensors connected), or when, for example, the ventilating unit 108 has "lost" power consumption data perhaps because of a break in communication with the controller 112. In this case the ventilating unit 108 may store temperature data which provides feedback for the fan speed control loop. In TX mode the 25 ventilating unit 108 may function according to the following logic: 1. Worst case temperature reading of all sensors with fans running at a common speed. In which case, fan speed may be based on, or calculated according to: * The highest temperature reading of all temperature sensors; 30 0 The inlet air temperature; and " Maximum allowable temperature.

OR

- 22 2. Individual temperature readings, individual fan speeds. In which casse fan speed may be based on or calculated accoridng to: * Proximity tables linking temperature sensors to equipment rack positions; 5 e Fan overlap tables; * Individual temperature readings; * Inlet air temperature; and * Maximum allowable temperature for each sensor. Thus, in TX mode the following information may be required: 10 e "Common fan speed" or "individual fan speed" selection information; " Fan overlap tables; " Maximum allowable temperature (for each sensor 106); and * Temp sensor to equipment rack position proximity tables. Example 4: TP Closed Loop - temperature data and power consumption data 15 In TP mode the ventilating unit 108 may functionin a similar way to the XP mode and the TX modes above except that the fan speed is set to the higher of the two values obtained via the XP mode and TX mode calculations. Thus, the following information may be required: " Common fan speed or individual fan speed; 20 * Aggregated power or individual power (each sensor); " Fan overlap tables; * Temperature sensor to equipment rack position proximity tables; and * Power outlet module to equipment rack position proximity tables. Example 5: Manual Control Mode 25 The ventilating unit 108 may also provide a manual control mode in which a user may independently set the speeds of each fan or set a common fan speed. The manual mode may also permit a user to read sensor data (such as incoming air temperature and the values of other sensors if connected) and any 30 other data which is available to the ventilating unit 108 (for example, power outlet module sensed power values). In embodiments of ventilating units 108 that support a manual control mode, a user may communicate with the ventilating unit 108 via a suitable - 23 communications interface, such as serial port using a terminal program such as Windows Hyperterminal or via web interface through the controller 112. As described earlier, the ventilating unit 108 may also provide output ports, such as PWM output ports, which can be used to control other ventilating 5 devices, such as exhaust fans. For example, the ventilating unit 108 may be able to control plural exhaust fans (at different speeds). Again, the ventilating unit 108 may support multiple modes for controlling the other ventilating devices, such as: * Manual control in which fan/s operate at a fixed set speed (0% to 100%); 10 * Variable fan speed based on temperature of the heated air at a sensed location (for example, the rear of an equipment rack); and * Airflow matching mode (where the outgoing air volume is matched to the incoming air volume). The following information may be entered: 15 e "Manual" or "temp closed loop" or "airflow match" selection information; * Related (proximal) temperature sensors; and e Maximum allowable temperature (for related sensors) (default is 30 0 C). Figure 8 shows a flow diagram illustrating the effect of an example start up process or a user initiated mode change. 20 In this example, in circumstances in which the mode of operation has changed because of the temporary loss of some input data the ventilating unit 108 will return to the previous operating mode as soon as conditions allow. For example, when electrical power is lost and restored the ventilating unit 108 will restart and attempt to run in the mode that was active prior to the loss of power 25 (according to the mode start-up rules above). In such a case, a "changed values" flag will be set to that that a power failure and restart has occurred. In some embodiments, each ventilating unit power supply unit (PSU) may be fed from independent AC supplies of power. In such a case, in the event of one feed of AC supply of power being lost or a PSU fails, the PSU 30 which is still operating will attempt to supply the entire ventilating unit 108. In the event that a portion of the AC supply of power is lost or degraded, the ventilating unit 108 may vary the operation of the ventilating devices 110 to compensate for the reduction in the available supply. For example, if only one PSU is operating and if the total power consumption of the ventilating unit 108 is - 24 above a predetermined maximum capacity (for example, 95%) of the PSU the ventilating unit 108 may reduce the fan speeds for all fans by applying a suitable control algorithm which reduces the overall power requirement of the ventilating unit 108. For example a new fan speed may be calculated as 5 follows: New Fan Speed = Previous Fan Speed * (Ventilating Unit Power Usage) / (95% PSU capacity) Alternatively, the distribution of fan speeds across all of the fans included 10 with the ventilating unit 108 may be altered. For example, six fans per side may run at "full" speed and six fans per side may be switched off completely. Such an approach may also provide an audible indication (suhch as an "alarm" that there is a problem. Alternatively, all fans may be controlled to operate at 50% PWM duty cycle. 15 In an embodiment, in order to keep the communications infrastructure clear of unnecessary traffic, the controller 112 will poll connected devices looking for a set "changed values" flag. In response to detecting a changed value from a device (such as a ventilating unit 108), the controller 112 will read data from that device, clear the flag, and determine an appropriate action. 20 Examples of actions which may result in a ventilating unit 108 setting a "changed values" flag include: * A temperature sensor reading changing by more than a predefined amount (for example, 5%); * The inlet air temperature changing by more than a predefined 25 amount (for example, 5%); * A device being connected or disconnected (console, sensor, etc); * A setting being changed via console input; * Power failure of one PSU; * Power failure and restart has occurred; 30 * A temperature threshold being exceeded; * A fan fault (for example, cannot start fan, speed is out-of-range for a given PWM output); * Communication lost with controller 112; - 25 " An operating mode change occurring which wasn't initiated by the user; * Temperature data or power consumption data being lost; and " Filter clogged - the test for this can be initiated by the user or set up 5 by the user to occur at preset intervals (eg. once per week). Fan Control In one embodiment, six variables influence the operation of the fans, namely fan minimum speed (RPM), fan maximum speed (RPM), spin up time (seconds), temp minimum (*C) (or Current Minimum (Amps)), temp maximum 10 (*C) (or current Maximum (Amps)), temp Hysteresis (*C) (or current Hysteresis (Amps)). There is also a temperature (Tmin) below which a fan does not operate. Once Tmin is exceeded the fan spins up and settles to the minimum fan speed. There is then a linear relationship between temperature and fan speed. If the 15 temperature drops below Tmin the fan does not immediately switch off. This provides hysteresis which stops fans cycling on and off unnecessarily around the Tmin point. The same method applies for fan speed vs power consumption. Cooling Logic (Variables and Setup Data) 20 The following tables describe example relationships between ventilating devices 110, power outlet module 302 electrical outlets, temperature sensors and equipment rack positions as well as examples of user settings available for each. Note that in these examples the power outlet module 302 electrical 25 outlets are numbered "1" to "24". Ventilating devices 110 are numbered "1" to "12" for the left side bottom up and "13" to "24" for the right side bottom up. Equipment rack positions are identified from the bottom up ("1" to "45"). Operating Parameters Table 1 provides a relationship between equipment rack positions and 30 ventilating devices 110 of a ventilating unit 108. A "1.0" in table 1 indicates that a position is completely dependent on a particular ventilating device 110 for its cooling. A value less than "1.0" indicates that the position is partially cooled by a ventilating device 110. For example, where a position falls directly between two ventilating devices 110 (such as fans) the position will be indentified as two - 26 values of 0.5 per fan. As will be appreciated, the row sum of each position will always equal 1.0. In later tables, where positions are associated to power outlet module 302 outlets and temperature sensors, the position/fan table (such as table 1) will 5 be used by the cooling logic to determine which ventilating devices (in this example, a fan or fans) are responsible for maintaining a sensor temperature or countering the heating effects of installed equipment items for which power consumption is being measured. Ventilating Unit No.1 Rack RU Left Side 1 2 3 4 5 711 12 1 2 1.0 1 2 1.0 1 3 1.0 1 4 0.7 0.3 1 5 0.3 0.7 1 6 1.0 1 7 1.0 1 8 0.7 0.3 1 9 0.3 0.7 1 10 1.0 1 11 1.0 1 12 0.5 0.5 1 13 1.0 1 14 1.0 1 15 0.7 0.3 1 16 0.3 0.7 1 17 1.0 1 40 1.0 1 41 0.5 0.5 1 42 0.5 0.5 1 43 1.0 1 44 1.0 1 45 1.0 Table 1 - 27 In this example, exhaust fan PWM output ports are mapped to an equipment rack 102 as shown in Table 2. Ventilating Unit No.1 Rack RU Exhaust fan PWM Port 25 261 1 - X 2 -X 5 Table 2 Fan settings may also be expressed in terms of operating parameters having default values (example default values are shown in the Table 3). The operating parameters may describe the operation of all fans. Example 10 operating parameters, and associated default values, are listed in Table 3. Fan minimum speed (rpm) 800 Fan maximum speed (rpm) 4800 Fan spin-up time (seconds) 2 Fan airflow at minimum speed (cfm) 25 Fan airflow at maximum speed (cfm) 110 Hysteresis (%) 20 Table 3 - 28 Table 4 identifies an example association between the electrical outlets of a twenty-four port power outlet module and the positions of an equipment rack 102. In the present case, this data is entered or programmed into ventilating unit 110 by a user operating the input device. 5 Power Outlet Module No.1 Rack Pos. 1 2 3 4 5 16 7 8 ... 22 23 24 11 X 1 2 X 1 3 X 1 4 X 1 5 X 1 6 1 7 X 1 8 X 1 9 X 1 10 X 1 11 X 1 41 X 1 42 X 1 43 X 1 44 X 1 45 Table 4 - 29 As shown in Table 5, temperature sensors may also be associated with positions in an equipment rack 102 which will in turn associate the sensors with fans as per the fan table provided at Table 1. Rack Pos. Temperature Sensor 1 1 1 2 1 3 1 4 1 5 1 6 x X 1 7--x 1 8--X 1 9 x 1 10-X 1 11---x 1 38---X 1 39---x 1 40---X 1 41---X 1 42 X x 1 43---x 1 44 X 1 45 XX XX 5 - 30 As shown in Table 6, each temperature sensor may also be assigned a minimum and maximum temperature threshold defining an acceptable temperature range for equipment items located in a position monitored by the sensor. Such a configuration is expected to provide further benefits and 5 improved flexibility since it may permit an equipment rack to be configured based on the operating environmental requirements for the installed equipment items. Temp Min Temp (*C) Max Temp (*C) Sensor 1 21.0 41.0 2 20.0 31.0 3 26.0 31.0 4 23.0 36.0 10 Table 6 In this example, once some or all of the above data is entered or programmed into a ventilating unit 108, each ventilating device 110 will then be controlled according the mode of operation. By way of an example, in a closed loop mode each fan will operate at the worst-case temperature/current settings. 15 In other words, if a fan is associated with "Sensor 1" from Table 6 (Tmin 21*C, Tmax 41 0 C) and Sensor 3 (Tmin 26*C, Tmax 310C) its automatic fan speed control loop will use Tmin 26*C and Tmax 31*C. In other words, the fan speed control loop will use the highest minimum and the lowest maximum temperature. Similar logic would apply for power consumption. 20 In an embodiment where fans are responsible for cooling nearby positions as well as the position immediately adjacent to the fan, the fan speed may be based on the cumulative cooling requirement. It is to be understood that various additions, alterations, and/or modifications may be made to the above-described embodiments without 25 departing from the ambit of the invention.

Claims

1. An equipment rack for housing one or more electrical equipment items, the equipment rack including: 5 a structure for supporting each electrical equipment item in one or more positions in the equipment rack; for each position, one or more sensors for sensing a parameter value attributable to the electrical power demand of each equipment item located at the position, and one or more associated ventilating devices for supplying a 10 ventilating gas; and a controller in communication with each sensor and ventilating device, the controller receiving and processing each sensed parameter value and controlling the volume and/or temperature of the ventilating gas supplied by each ventilating device according to the sensed parameter value(s) for the 15 associated position.

2. An equipment rack according to claim 1 wherein each sensor includes a current sensor for sensing the current supplied to the one or more equipment items at a respective position so that the sensed parameter value includes a 20 sensed value of electrical current.

3. An equipment rack according to claim 2 wherein the sensed current is an instantaneous current. 25

4. An equipment rack according to claim 1 wherein each sensor includes a power sensor for sensing the electrical power supplied to the one or more equipment items at a respective position.

5. An equipment rack according to claim 4 wherein the sensed power is 30 instantaneous power.

6. An equipment rack according to any one of claims 1 to 5 wherein the or each ventilating device includes one of: - 32 a. a fan; b. a heat exchanger; or c. an air conditioning device. 5

7. An equipment rack according to any one of claims 1 to 6 wherein the equipment rack further includes one or more additional sensors for sensing an environmental parameter at a respective position, each sensor in communication with the controller, and wherein the controlling of the volume and/or temperature of the ventilating gas supplied by each ventilating device 10 has a dependency on the sensed environmental parameters.

8. An equipment rack according to claim 7 wherein the sensed environmental parameters includes one or more of: a. temperature; and 15 b. humidity.

9. An equipment rack according to any one of claims 1 to 8 further including a power outlet module including multiple electrical outlets for electrical connection with electrical inputs of the equipment items, and wherein each 20 sensor is operatively associated with a respective one of the electrical outlets of the power outlet module.

10. An equipment rack according to claim 9 wherein the power outlet module includes an interface for communicating a signal to the controller, the signal 25 encoding the sensed parameter values.

11. An equipment rack according to claim 9 or 10 further including a programmable memory storing, for each electrical outlet of the power outlet module, data encoding an identifier associating the electrical outlet with a 30 position of the equipment rack.

12. An equipment rack according to claim 9 or 10 further including a programmable memory storing, for electrical outlet of the power outlet module, -33 data encoding an identifier identifying the position of the equipment item connected to the electrical outlet.

13. An equipment rack according to any one of claims 9 to 12 wherein the 5 signal encoding the sensed parameter values also encodes, for each sensed parameter value, the identifier for the location associated with each sensed parameter value.

14. An equipment rack according to any one of claims 1 to 13 further 10 including a programmable memory storing operating values associated with the ventilating devices.

15. An equipment rack according to claim 8 wherein controlling the volume and/or temperature of the ventilating gas supplied by a ventilating device for a 15 position includes calculating a value of fan speed based on the sensed temperature.

16. An equipment rack according to any one of claims 1 to 15 further including an input device for accepting configuration information from a user, 20 the configuration information identifying an association between each position of the equipment rack and one or more respective ventilating devices and/or sensors.

17. An equipment rack according to claim 16 wherein the configuration 25 information identifying an association between each position and the one or more respective ventilating units is expressed in terms of a weighted numerical value expressing a proportion of the output capacity of the one or more ventilating devices associated with a position. 30

18. An equipment rack according to claim 17 wherein each ventilating device is assigned a weighted numerical value for plural positions of the equipment rack. - 34

19. An equipment rack according to claim 18 wherein, for each ventilating device, the volume and/or temperature of the ventilating gas is controlled according to the sensed parameter value or values for each position having an identified association with the ventilating device, to an extent that depends on 5 the associated weighted numerical value for each respective position.

20. An equipment rack according any one of claims 14 to 19 wherein the operating parameters include one or more of: a. fan minimum speed; 10 b. fan maximum speed; c. fan spin-up time; d. fan airflow at minimum speed; e. fan airflow at maximum speed; and f. hysteresis. 15

21. A ventilating unit for an equipment rack, the ventilating unit including: a housing for housing one or more variable speed ventilating devices; a microprocessor with an associated programmable memory containing a set of program instructions that are executable by the microprocessor; 20 a control circuit in communication with the microprocessor and the one or more ventilating devices; and a communications interface; wherein the programmable memory stores, for each ventilating device, data encoding an association between each ventilation device and a position in 25 the equipment rack, and wherein the communications interface is configured to receive a signal containing sensed parameter values attributable to the electrical power demand of one or more equipment items located in a position of the equipment rack, the signal being decodable by the microprocessor under the control of the program instructions to cause the control circuit to vary the 30 speed of the ventilating devices in accordance with the sensed parameter values for the associated position.

22. A ventilating unit according to claim 21 wherein the programmed memory contains data encoding operating values specifying operating parameters for -35 each of the one or more ventilating devices and wherein the operating parameters include one or more of: a. fan minimum speed; b. fan maximum speed; 5 c. fan spin-up time; d. fan airflow at minimum speed; e. fan airflow at maximum speed; and f. hysteresis. 10

23. A power outlet module including one or more electrical outlets for connecting to an equipment item, the power outlet module including: a housing for housing the one or more electrical outlets; for each outlet, a sensor for sensing a parameter value attributable to the electrical power demand of an equipment item connected to the electrical outlet, 15 each sensor being associated with a respective one of the electrical outlets; a microprocessor with an associated programmable memory containing a set of program instructions that are executable by the microprocessor, and data encoding a unique identifier for each electrical outlet; and a communications interface; 20 wherein execution of the program instructions causes the microprocessor to process sensed parameters values and output from the communications interface a signal containing data derived from the sensed parameters values together with the unique identifier for the electrical outlet associated with the sensed parameter. 25

24. A power outlet module according to claim 23 wherein the unique identifier for each electrical outlet is in the form of information identifying the position in an equipment rack of an equipment item connected to the power outlet. 30

25. A power outlet module rack according to claim 23 or 24 wherein the sensed parameter value includes a sensed value of electrical current. - 36

26. A power outlet module according to claim 25 wherein the sensed current is an instantaneous current.

27. A power outlet module according to claim 23 or 24 wherein the sensed 5 power is instantaneous power.

28. A system for monitoring and controlling the ventilation of one or more equipment racks, each equipment rack housing one or more electrical equipment items, the system including: 10 one or more sensors for sensing a parameter value attributable to the electrical power demand of an equipment item located in a position of an equipment rack; for each equipment rack, a ventilating unit including one or more variable output ventilation devices configured to supply a ventilating gas to one or more 15 positions in the equipment rack; and a controller in communication with each sensor and ventilating device, the controller for receiving and processing each sensed parameter value and controlling the volume and/or temperature of the ventilating gas supplied by the ventilating device(s) so that, for each position, the volume and/or temperature of 20 the ventilating gas is controlled according to the sensed parameter value or values for that position.

29. A system according to claim 28, further including a server computer in data communication with at least one controller of 25 an equipment rack; and a client computer operatively connected to the server computer, the client computer being operable by a user to display status data received from a selected one or more of the controllers in data communication with the server computer. 30

30. A system according to claim 28 or 29 wherein the status data includes one or more of: a. sensed environmental data; b. sensed electrical power data; and - 37 c. operational data.

31. A method of regulating the temperature of an equipment rack housing one or more electrical equipment items in different positions of the equipment 5 rack, the method including: for each position, sensing a parameter value attributable to the electrical power demand of each equipment item located in the equipment rack; processing each sensed parameter value; controlling the volume and/or temperature of a ventilating gas supplied by 10 a ventilating unit including one or more ventilating devices associated with one or more of the positions so that, for each position, the volume and/or temperature of the ventilating gas provided by a ventilation device is controlled according to the sensed parameter value or values for the associated position. 15

32. An equipment rack substiantially as hereinbefore described with reference to the accompanying figures.

33. A power outlet module substiantially as hereinbefore described with reference to the accompanying figures.