The purpose of this document is to provide information, formulas and documentation to take certain electrical values and convert them into other electrical values. The formulas below are known and used universally but we use them here in association with computer, network, telecom and other IT equipment.
To Find Watts
To Find Volt-Amperes
To Find Kilovolt-Amperes
To Find Kilowatts
To Convert Between kW and kVA
TO Find kBTUs from Electrical Values
Background
It is often necessary to turn voltage, amperage and electrical “nameplate” values from computer, network and telecom equipment into kW, KVA and BTU information that can be used to calculate overall power and HVAC loads for IT spaces. The following describes how to take basic electrical values and convert them into other types of electrical values.
- NOTE #1:
The informational nameplates on most pieces of computer or network equipment usually display electrical values. These values can be expressed in volts, amperes, kilovolt-amperes, watts or some combination of the foregoing.
- NOTE #2:
If you are using equipment nameplate information to develop a power and cooling profile for architects and engineers, the total power and cooling values will exceed the actual output of the equipment. Reason: the nameplate value is designed to ensure that the equipment will energize and run safely. Manufacturers build in a “safety factor” when developing their nameplate data. Some nameplates display information that is higher than the equipment will ever need – often up to 20% higher. The result is that, in total, your profile will “over engineer” the power and cooling equipment. Electrical and mechanical engineers may challenge your figures citing that nameplates require more power than necessary.
- NOTE #3:
Our advice: Develop the power and cooling profile using the nameplate information and the formulas below and use the resultant documentation as your baseline. Reasons: (1) it’s the best information available without doing extensive electrical tests on each piece of equipment. Besides, for most projects, you are being asked to predict equipment requirements 3-5 years out when much of the equipment you will need hasn’t been invented yet. (2) the engineers will not duplicate your work; they do not know what goes into a data center. They will only challenge the findings if they appear to be to high. If the engineers want to challenge your figures, it’s OK but have them do it in writing and let them take full responsibility for any modifications. If you must lower your estimates, do so. But, document everything. There will come a day in 3-5 years when you will need every amp of power you predicted. We’ve had projects where it was very evident within six months that what we predicted would come true – sometimes even earlier than we estimated.
- NOTE #4
If you are designing a very high-density server room where you will have racks and racks (or cabinets and cabinets) of 1U and 2U servers tightly packed, you need to read our article entitled “IT Pros – Don’t be Left in the Dust on IT Server Room Design”.