SFP+
Small Form-factor Pluggable (SFP) Plus. High-density/high-bandwidth interconnect system used between servers and switches in data centers.
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Leave a Comment (0) →Set Point
In a control system, this is the value against which the variable that is being controlled is compared. Temperature and humidity set points are common in the cooling system for a data center.
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A computer or computer program that manages access to a centralized resource or service in a network.
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Leave a Comment (0) →Sensible Cooling
The action of lowering the dry bulb temperature of air without condensation taking place.
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Leave a Comment (0) →Secondary Loop
Refers to the water which is used to cool the heat exchangers in AHUs and is cooled via the expansion unit in a chiller.
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Leave a Comment (0) →RPP
Remote Power Panel. Electrical power distribution panel.
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A network device that forwards packets from one network to another. Based on internal routing tables, routers read each incoming packet and decide how to forward it. The destination address in the packets determines which line (interface) outgoing packets are directed to. In large-scale enterprise routers, the current traffic load, congestion, line costs and other factors determine which line to forward to.
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Leave a Comment (0) →Rooftop Unit (RTU)
An air handler designed for outdoor use mounted on a rooftop.
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Leave a Comment (0) →ROI
Return on Investment, a measure of the money that an entity earns as a percentage of the total value of its assets that are invested.
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Relative Humidity. The amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature.
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Leave a Comment (0) →Return Air
The heated air returning to air conditioning equipment.
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Leave a Comment (0) →Recirculation Air Handler (RAH)
A device that circulates air but does not cool the air.
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Air which exits IT equipment and then re-enters either the same IT equipment or another piece of IT equipment without being cooled. Typically caused by poor control of airflow due to missing blanking panels, gaps in rows, insufficient air supply, etc.
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Leave a Comment (0) →Raised Metal Floor (RMF)
An alternate term for the more commonly used term ‘raised floor’.
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Metal flooring on stanchions that creates a plenum for airflow and cabling, synonymous with RMF.
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Leave a Comment (0) →Rack Unit (RU)
Vertical mounting space of 1.75 in (44.45 mm) for cabinets or racks compliant with IEC 60297 or CEA-310-E.
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Leave a Comment (0) →Primary Loop
Refers to the water loop which cools the condenser side of a chiller. This loop is cooled by dry coolers or cooling towers.
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Leave a Comment (0) →Pressure Differential
The difference in pressure between two locations in the data center. Air flows from higher pressure areas to lower pressure areas. Often times, the pressure differential between the under-floor plenum and the above-floor space is controlled by varying the speed of the fans supplying air to the under-floor plenum. This allows the addition of vented floor tiles to occur without affecting the air delivered to existing vented floor tiles so that additional IT load may be placed on the floor without disturbing the tuning of the existing floor.
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Leave a Comment (0) →Power Usage Effectiveness (PUE)
A metric defined by the Green Grid, which is a measure of data center efficiency calculated by dividing the total data center energy consumption by the energy consumption of the IT computing equipment. This measure is the inverse of DCiE.
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Leave a Comment (0) →Power Factor (PF)
Represents the portion of the apparent power that is real power. The source of power factor is non-resistive components (inductors and capacitors) in the load on an AC power system. These components draw current that is 90 degrees out of phase with the voltage across them resulting in zero real power being delivered. While the power delivery system must carry this current (as well as all the current which does result in real power being delivered), it does no useful work. Power companies often charge a penalty for loads which have a power factor that is significantly far away from 1.0 since the size of the equipment that must be in place is dependent upon the total current delivered, but normal billing is based on real power delivered.
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