Patent Application
20120120559
Power distribution units (PDUs) for electrical equipment racks such as RETMA racks are becoming highly sophisticated. Once little more than a simple plug-strip, today a PDU may include complex circuitry that can perform such functions as switching any of numerous outlets off and on, receiving commands from and transmitting data to remote power managers, and controlling power sources such as uninterruptible power supplies (UPSs). Such a PDU may include a microprocessor and embedded software and may be accessed through a web browser under control of a remotely-located user. Examples of such PDUs may be found in U.S. Pat. Nos. 7,116,550, 7,137,850, 7,171,461, and 7,196,900, all of which are incorporated herein by this reference.
Physical space that can accommodate a PDU in an equipment rack is at a premium because most of the space in such a rack is occupied by computers and other electronic appliances. Most or all of these appliances draw power from the PDU. Accordingly, PDUs typically are built in long, narrow, tight enclosures that have barely enough room to accommodate one or more power inlets and up to 24 or more power outlets. Such PDUs are often designed with a vertical form factor to facilitate mounting vertically in a back corner area of an equipment rack, out of the way of the appliances in the rack but accessible from the rear of the rack so that the appliances can readily be plugged into and unplugged from the outlets.
In general, PDU housings have not expanded despite the addition of more complex circuitry that gives the PDUs more capabilities. However, this circuitry generates heat, and as more such circuitry is added into the confined space of a PDU housing, dissipating this heat has become a significant problem.
Adding to the heat dissipation problem has been the trend to install increasingly-complex computers and other appliances, and more of them, in electrical equipment racks. This has had the effect of generating more heat within the rack, making more demands on the PDU and thereby increasing the amount of heat generated by circuitry within the PDU, and reducing the volume of air in the rack that can dissipate that heat. The combination of more heat generated in a confined space within the PDU, more heat generated by the appliances in the rack, and less air space in the rack, has led to great difficulty in keeping the internal temperatures within PDUs within safe limits.
The general problem of thermal management in equipment racks has been recognized, and various methods and devices have been proposed for cooling computers, computer power supplies, and other appliances in an equipment rack. By way of example, in U.S. Pat. No. 7,173,821 issued to Coglitore, it is proposed to install various appliances back-to-back in a rack with an overhead power supply, with cooling air to flow between the appliances, and to locate a central power supply in a rack by itself with a dedicated cooling system.
Briefly and in general terms, the problem of heat dissipation in an equipment-rack PDU is solved by circulating cooling air through the PDU. An equipment-rack power distribution system according to an embodiment includes a PDU housing, a power input penetrating the housing, a plurality of power outlets disposed on a surface of the housing, circuitry enclosed in the housing interconnecting the power input and the power outlets, one or more air inlets associated with the housing, one or more air outlets associated with the housing, and an air flow device coupled to at least one of the air inlets and the air outlets.
Spaces between the outlets and the housing may be closed with gaskets. The air flow device may include a fan and a conduit defining an air passage between the fan and the housing. In an embodiment having two fans, a baffle may be pivotingly disposed between the fans so that when both fans are activated the flow of air from the fans urges the baffle into a neutral position and when one fan is activated the flow of air urges the baffle against the other fan. An environmental sensor, such as a thermostat, may be used to activate the fan depending on temperature inside the PDU housing.
As shown in
A power input 111 penetrates the housing 101 and provides power to the PDU. The power input may be in the form of a single-phase power cord and plug as shown, it may be a 3-phase power cord and plug, or it may be a permanently-wired electrical supply such as Romex cable or the like. The power input may, in some embodiments, include dual or redundant power inputs. Power outlets 113 are disposed in a surface 115 of the housing. Circuitry (not shown) enclosed in the PDU housing interconnects the power input and the power outlets and may perform other functions such as sensing parameters of electrical power flow through the outlets, controlling the outlets, and communicating with an external power manager application (not shown).
An air inlet 117 is disposed in a first end 119 of the housing. In the illustrated embodiment, an air flow device 121 is coupled to the air inlet. In another embodiment as shown in
Returning to
A plurality of gaskets such as the gasket 131 may be used to minimize air leakage around the power outlets. Each such gasket forms a seal between one of the outlets and the housing. The gaskets may be rubber, synthetic rubber, or some other substance that conforms to the edges of the outlet and the surface 115 of the housing.
The air flow device 121 may include at least one fan 133 and a conduit 135 defining an air passage between the fan and the housing. It will be readily understood that an air flow device may, in other embodiments, may include more or fewer components, such as simply a fan located within, or immediately adjacent to, the PDU housing. Wit continuing reference to the air flow device 121 of the embodiment of
Some embodiments may omit the fan. Air within the housing is warmed by wiring and circuitry in the housing and rises, exiting the housing at the top. This results in fresh, relatively cool air being drawn into the housing at the bottom, setting up a flow pattern of air flowing into the housing at the bottom, drawing heat from the circuitry and wiring in the housing, rising as it draws the heat, and exiting the housing at the top. Conduits may be used to provide air flow paths from the exterior of the rack to the bottom of the housing or from the top of the housing to the exterior of the rack or both. In the illustrated embodiments, An air flow device may be coupled to the air inlet, which may be located at or near either the top or bottom of the housing, so that the device urges cool air through the conduit into the housing. Warmed air is thereupon expelled through the air outlet at or near the opposite end of the housing. An air flow device, in other embodiments, may be coupled to the air outlet to draw warm air out of the housing. In some embodiments air flow devices are used at both the air inlet and the air outlet. The air outlet may, in some embodiments, in clued a plurality of openings in the PDU housing that allow air that is urged into the housing through the air inlet(s) to exit the PDU housing and draw heat away from components within the housing. The air outlets may be located uniformly along one or more surfaces of the housing, or may be located to provide enhanced air flow around certain components within the housing.
In embodiments having a fan, the fan draws cool air, for example, from outside the equipment rack as in the embodiments shown in
Two fans may be installed adjacent each other as shown in
An environmental sensor, such as a thermostat, shown generally as 165, may be used is some embodiments to provide enhanced cooling. The environmental sensor 165 is in electrical communication with the fans and is responsive to temperature in the housing to activate, none, one, or more fans as needed to keep the temperature inside the housing within desired limits. The thermostat may include a temperature sensor (not shown) inside the housing, for example.
More than two fans may be provided according to some embodiments. A third fan 167 and a fourth fan 169, for example, may be installed in the panel 151 and enclosed in a conduit 171. The conduit 153 may extend to the air inlet 227 of the housing and the conduit 171 may extend to the air outlet 123. The fans 149 and 151 would draw cool air from outside the rack and urge it into the housing, and the fans 167 and 169 would draw warm air from the housing and urge it out of the rack. Or the conduit 171 may join the conduit 153 to provide a higher rate of air flow or to provide more precise control over the volume of cooling air flow by allowing for selective activation of various ones of the fans.
A cooling system constructed according to an embodiment was tested. Sensors were used to detect the actual temperatures of various components within the PDU. First the system was testing with no cooling and with a nominal ambient temperature of 50° C. in the interior of the rack. Next the system was tested with cooling in operation and the same ambient temperature. Finally the system was tested with cooling in operation and a nominal ambient temperature of 70° C. in the interior of the rack.
In the first test sequence, the actual ambient temperatures (line 8) exceeded the nominal ambient temperatures. With no cooling, the temperatures of the various components (lines 1-6) all significantly exceeded the ambient. With cooling, the temperatures of all components were substantially lowered, all but one component being well below the 50° ambient and all of them being substantially below the 70° ambient.
While various embodiments of the present invention have been described in detail, it is apparent that modifications and alterations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the following claims. Further, the invention(s) described herein is capable of other embodiments and of being practiced or of being carried out in various ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
The present Application for Patent claims priority to U.S. Provisional Patent Application No. 61/411,831 entitled “EQUIPMENT-RACK POWER DISTRIBUTION SYSTEM WITH COOLING” filed Nov. 9, 2010, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61411831 | Nov 2010 | US |
