A COOLING ARRANGEMENT FOR MAINTAINING A RACK CONTAINING OPERABLE ELECTRONIC MODULE EQUIPMENT WITHIN A SELECTED TEMPERATURE RANGE TECHNOLOGICAL FIELD [001] This invention relates to a cooling arrangement for maintaining the environment within electronic module equipment server racks for a selected temperature range and more particularly to a cooling arrangement which is able to maintain temperature within the server rack at the required preferred level using significantly less energy than current conventional methods. BACKGROUND ART [002] Electronic equipment is often designed nowadays to be modular so that it can be conveniently placed and mounted into racks and shelves within a standardised frame or enclosure in different configurations. [003] These kinds of racks are a recognised way in which electronic/electrical hardware configurations can be mounted within the one structure so as to avoid taking up too much floorspace. These racks are widely used for computer server equipment as well as other akin products including but not limited to, audio, entertainment and telecommunications. [004] As these racks are housing at least several electronic module pieces of equipment where each is potentially dissipating its own heat, this heat can become trapped inside the rack posing a risk to the operating integrity of the ambient temperature sensitive equipment within the rack. [005] The amount of heat dissipated by a specific electronic module or piece of equipment depends upon the computational load and/or how much data a particular computer server is processing based upon the demands of the system in which that equipment operates. [006] For example, take the situation in connection with a rack being used for computer server equipment, if the server is idle (not carrying out any tasks or processing) the electronic equipment within the rack will not necessarily generate much heat. Alternatively if the server is at a higher operating level where processing is significant, for example loading files or performing calculations, the server will then generate a much greater amount of heat. [007] Large computer server farms use sophisticated environment control systems to feed cool air into their computer racks. This keeps them cool and prevents overheating. These systems, as expected, are particularly expensive and are designed only to be deployed in large rooms with many racks, potentially hundreds if not thousands of servers. These systems are typically built into the facility at construction or during a significant refitting of the building. [008] While such arrangements may be useful on a large scale where there are many banks of server racks, the use of such sophisticated and expensive environmental control is not appropriate for smaller computer rack systems typically operated by small business and other organisations as they do not have the available finance and infrastructure to utilise this type of environmental control system. [009] These small computer rack systems operated by small businesses and so forth for the most part may use a split system air conditioner to keep the room cool and thus the equipment in the computer rack within safe operating temperatures. [010] Nonetheless the problem with this method is there is no guarantee that the cool air enters the computer rack. Unless ducted air circulation is used, the hot air vented from the computers can still be trapped in the rack. So while the room is cool, the equipment is operating in a warm environment that could lead to malfunction or damage. [011] Also, these types of cooling methods simply based on keeping the room temperature cool do not take into account the actual load on the server or the piece of electronic equipment as to whether it is generating a lot heat or a minimal amount of heat. In an attempt to safeguard the electronic equipment inside the rack and keep it as cool as possible the room air conditioning is 2 often set at a very cool temperature so that in the event that the load on the server is significant the air temperature in the room will be cool enough to keep equipment in the rack within safe operating conditions. [012] While introducing split system air conditioning may increase air circulation in the room and into the server rack, it is particularly energy intensive. Electricity is expensive and the price is on the increase which makes the split system air conditioner method of keeping computers in a rack cool, inappropriate, if energy and costs are to be minimised. [013] While there are some fan systems available to try to remove generated heat from racks, these fans are designed to run at their maximum speed regardless of the degree of heat being generated within the rack. [014] As introduced above, there will be times when the electronic module equipment within the rack is not operating at full capacity and therefore the heat generation is much less. Thus it would be a waste of energy to be running fans at maximum speed to push air through the racks if minimal heat is being generated during 'idle' times and so forth. [015] It is an object of this invention to provide a cooling arrangement that is able to maintain the air temperature in an electronic module equipment server rack within a selected temperature range without using sophisticated environmental control systems associated with large scale facilities or the energy intensive alternatives of using split system air conditioners and/or running fans at maximum speed continuously so that excessive heat build up within the rack is avoided. [016] Further objects and advantages of the invention will become apparent from a complete reading of this specification. SUMMARY OF THE INVENTION [017] A cooling arrangement for maintaining a rack or bank of racks containing operable electronic module equipment within a selected temperature range, said arrangement including; 3 a main housing unit adapted to be fastenable within the rack; said main housing unit including a programmed and/or programmable controller; said controller in electronic/electrical communication with a sensor arrangement monitoring temperature within the rack; said controller in electrical power communication with an air flow fan to power said fan at a required speed dependent upon a sensor reading taken from the sensor arrangement relative to a selected temperature range programmed into the controller. [021] An advantage of such an arrangement is that rather than simply having a fan system that has fixed speeds that are run at a maximum speed all of the time even when the electronic module equipment contained within the rack is not generating heat, this invention through the unique interaction between the controller, sensor arrangement and the ability to control the amount of electrical power being sent to the air flow fan, means that the speed of the fan and the power consumption used by the fan can be minimised or increased depending upon the temperature measured by the sensor. [022] It is the controller, which by varying the amount of power being sent to the air flow fan, which can control the speed of the connected fan, as introduced above, is dependent on the temperature measured by the sensor arrangement. The controller, by varying the amount of power sent to the airflow fan, can control the speed of the connected fan dependent upon the temperature measured by the sensor arrangement, as introduced above. [023] As the temperature inside the rack changes, the controller will change the speed of the connected air flow fan attempting to moderate the temperature inside the rack to the temperature which has been selected and/or programmed into the controller. [024] In preference the sensor arrangement includes multiple sensors locatable within the rack including locations, but not limited to only these 4 locations, at the top, bottom, rear, front and/or in close proximity to electronic/electrical pieces of equipment in the rack requiring sensitive temperature control. [025] Advantageously the sensor arrangement does not necessarily require just the use of a single sensor. The arrangement in a preferred embodiment could be made up of a variety of sensors positioned throughout the rack monitoring certain locations or specific pieces of electronic/electrical equipment. [026] For example, a sensor positioned at the bottom of the rack can sense the temperature of air coming in from the outside environment and if that air is already at an unacceptable warm or hot temperature, outside the preferred operating temperature range, this information is then communicated to the controller which is then in a position to increase the speed of the connected fan so as to attempt to withdraw this incoming air from the rack as promptly as possible. [027] Preferably a sensor may also be located in close proximity to a particular electronic/electrical piece of equipment that is mounted within the rack of which temperature control is particularly sensitive, so as to make sure that this piece of equipment is operating under optimum conditions and not been effected by any adverse heating from within the rack. [028] There may be a requirement that this piece of electronic equipment be kept cooler relative to other module units and if there was just one single sensor away from this particular piece of equipment, precise readings of temperature relative to that particular electronic module may not be as accurate as possible. [029] The control arrangement in communication with the sensors can be such that when any sensor positioned throughout the rack reaches a pre determined level this then instigates a corresponding increase in speed to the connected fan. 5 [030] In preference the controller is in communication with multiple air flow fans. [031] In preference air flow fans may be housed in fan trays including multiple fans, wherein these fan trays are adapted to slide into shelving or slots configured as part of the rack. [032] In these embodiments the fan trays are adapted to be mounted within the rack to then be in electrical communication with the controller wherein the controller will be able to control the speed of these connected fans dependent upon the temperature measured by the sensors also connected and in communication with the controller. [033] In preferred embodiments the fan trays contain conventional power plugs which are insertable into an electrical socket as part of the housing of the controller. The housing arrangement contains wiring and electronics such that the power delivered to the power points varies with the temperature measured by the sensor. This affects the control of the fan speed dependent on the temperature measured by the sensors. [034] In preference the sensors are thermistors, temperature sensitive resistors. The resistance value changes as the thermistor heats up/cools down and the current passes through the thermistor which generates a voltage across the thermistor. The controller measures this voltage as a means of determining the temperature inside the rack at the point where the sensor is placed. [035] Nonetheless as introduced above, any sensor which is able to communicate a temperature change to the controller at the point to which it is monitoring would be suitable and in certain embodiments while the sensor may be plugged in through a port on the housing unit, other embodiments may include wireless communication between the sensor and the controller enclosed within the housing unit. 6 [036] In preference the housing unit further includes user interface features of a display screen and touch points so that the controller can be programmed for the required temperature range through said user interface. [037] By controlling the power delivered to the fans the controller alters the speed of the fans as required to moderate the temperature inside the rack to the control temperature set by the user through the user interface. [038] The fans assist in moving cool air into the rack and exhausting hot air from the rack. The air inside the rack heats up as the electronic module equipment housed within the rack attempts to exhaust the heat dissipated by. the electronics of the equipment. The airflow created by the fan trays removes this heat to prevent the whole rack heating up. The air flow advantageously also feeds cool air into the electronic module equipment for the equpment's own heat extraction system to prevent any overheating. [039] The controller can vary the airflow depending on the temperature measured by the sensors placed around the rack. Rather than having the fans operating continuously, they are being selectively powered and operating at speeds relative to the heat being generated in the rack. Energy is being saved and power consumption is being kept to minimum. [040] In preference the main housing unit also encloses multiple fans that assist in moving cool air into the rack and exhausting hot air from the rack. [041] Advantageously in this preferred embodiment the cooling arrangement is one complete unit with the air flow fans incorporated within the same piece of equipment. [042] In order now to describe the invention in greater detail preferred embodiments will be now described with reference to the following illustrations and accompanying text. BRIEF DESCRIPTION OF THE DRAWINGS [043] Figure 1 is a schematic representation of a preferred embodiment of the invention. 7 [044] Figure 2 is a schematic representation of a further preferred embodiment of the invention. [045] Figure 3 shows the preferred embodiment illustrated in Figure 2 being mounted within a rack housing multiple pieces of electronic/electrical equipment. [046] Figure 4 is a schematic representation of a further preferred embodiment of the invention. [047] Figure 5 is a schematic representation of the cooling arrangement being used to cool several banks of electronic module equipment racks. DETAILED DESCRIPTION OF THE DRAWINGS [048] Referring to Figure 1 wherein a simplified preferred embodiment of the invention is shown schematically in order to appreciate the basic requirements in order to achieve the outcome of the invention. [049] The embodiment is shown generally as (10) and includes a main housing unit (12) which contained therein includes a programmed and/or programmable controller (14). [050] The controller (14) is in communication with the sensor (20) which is electrically/electronically connected through wiring (18) into the appropriate socket or port (16) within the housing unit (12). [051] A sensor (20) would be placed inside the rack and its measured temperature is checked against the programmed or selected temperature that has been inputto the controller (14) by a user. [052] Depending on the measured temperature by the sensor (20) this will then allow the controller (14) to decide the degree of power that needs to be sent along line (24) to the fan (26) that has been connected via the socket (22) of the housing unit (12). [053] Under a conventional arrangement, the fan (26) would have a fixed speed that runs continuously while being switched on, regardless of whether 8 the electronic/electrical equipment within the rack were generating heat or otherwise. [054] Advantageously in this invention by having a controller controlling the speed of the fan (26) which would be dependent upon the sensed temperature by the sensor (20) means that in times when the electronic/electrical pieces of equipment mounted in the rack are not generating heat, power sent to the air flow fan can be reduced accordingly and vice versa when there is a sensed build up of heat. [055] As introduced above, in a preferred embodiment the sensor may be a thermistor. A current passes through the thermistor that generates a voltage across the thermistor. The controller (14) measures this voltage as a means of determining the temperature inside the rack at the point where the sensor (20) is placed. [056] In Figure 2 the preferred embodiment shown generally as (27) including a main housing unit (28) which is adapted to be fitted into one of the shelves of a rack which the arrangement is intended to cool. [057] Preferably in the embodiment the housing unit (28) would be of comparative dimensions so as to comfortably sit within a particular shelf or level of the rack being cooled and includes the fastening points (30a) and (30b) to help this attachment to the rack. [058] The arrangement (27) shown in Figure 2 also has user interface functionality which includes a display (32) and touch points (34) wherein a user can program as required the controller so the cooling arrangement operates such that the rack's temperature is within the preferred operating range. [059] In the embodiment shown for Figure 2 there are multiple sensors working in communication with the controller wherein ports (36a), (36b), (36c) and (36d) are connected to corresponding sensors (38a), (38b), (38c) and (38d) via appropriate wiring. 9 [060] In other preferred embodiments the controller housed withinside the main unit (28) can be in wireless communication with the sensors (38a), (38b), (38c) and (38d). [061] The housing unit (28) also includes multiple sockets shown as (40a), (40b), (40c) and (40d) wherein air flow fans can be individually plugged in as shown by way of air flow fan (44) through the electrical cord (42) or alternatively multiple fans (48a), (48b) and (48c) can be driven from the same socket (40c) by the electrical cord (46), such as in a fan try configuration. [062] Referring to Figure 3 wherein an arrangement similar to the one described in Figure 2, referred to as (56) can be fastened into a rack (50) that has pieces of electronic/electrical equipment (61) mounted therein. The rack (50) has ventilation ports (52a) and (52b) at the top of the rack (50) along with ventilation holes or slots (54a) and (54b) at the base of the rack (50). [063] A sensor (59) is placed towards the top of the rack such that if air leaving the rack is too hot the controller can increase the air flow to the electronic equipment via the multiple fans (57) included as part of a fan tray (60) which has been inserted into a shelf of the rack (50) towards the top of the unit. [064] A sensor (62) is positioned at the rear of the rack (50) as some electronic/electrical module equipment (61) are arranged such that their internal fans tend to blow hot air from front to rear. [065] Sensor (64) is also included as part of the sensor arrangement and in this embodiment sits in close proximity to the electronic module equipment (63) which is a piece of equipment which requires its own independent monitoring to make sure that if there is an excess of heat build up that the controller can operate, the fan speed as such to extract the heat away as required. [066] The arrangement also includes sensor (66) which is positioned towards the bottom of the rack (50) below the individually stacked or shelved electronic module units (61) that have been positioned inside the rack (50). 10 [067] Sensor (66) it is able to virtually instantaneously recognise that if air. coming into the rack (50) is already hot, the controller can increase the air flow to remove this excess heat more quickly. [068] The air flow fan tray (60) is connected to one of the electrical sockets that have been included as part of the unit (56) and as explained in reference to Figure 2 controlling the power delivered to the fan tray alters the speed of the fans as required to moderate the temperature inside the rack to keep the temperature within the range set by the user. [069] Figure 4 refers to an embodiment wherein the fan tray which is shown as a separate unit to the housing unit (56) in Figure 3 is in fact integral and as the general arrangement (66) shows the unit (68) also encloses as part of the main housing block (68) individual fans (70a), (70b) and (70c). [070] Nonetheless the principle still remains the same in that sensors can be connected at locations (72) to the housing unit (68) and the user will be able to interface through touch point (76) with the selected range being able to be displayed at (74). [071] The unit (68) also includes some electrical sockets which can be used to power separate fans if required. [072] Figure 5 looks at the embodiment wherein a single control unit (86) is assisting in the cooling of banks or columns (80), (82) and (84) of different racks. [073] As is to be appreciated the embodiment is shown schematically and additional sensors as well as the location of the unit (86) itself and the corresponding air flow fan trays (94), (96) and (98) can be multiplied and located at various locations within each rack (80), (82) and (84) as required. [074] But the principle still remains the same in that a sensor or sensors are responsible for sensing a temperature at a certain location and that temperature information is fed to a controller which will then control power delivered to the fans (94), (96) and (98) and alter the speed of the fans as 11 required depending on the temperature sensed by the respective sensors (88), (90) and (92). [075] In some embodiments individual sensors are connected to individual airflow fans or airflow fan trays within the rack. [076] Alternatively multiple sensors through the controller are effectively controlling the use of the same airflow fan or airflow fan trays thereof such that any one of the multiple sensors reaches a threshold this will then signal to the controller that it needs to send further power to the fan to increase the fan speed so as to maintain the temperature inside the rack at the selected or within the controlled temperature range set by the user. 12