kilo Volt Amperes (kVA) and What is it?
Paul Webb, Energy Expert
Founder of B2B Energy Ltd | Chartered Energy Manager MEI, ESOS Lead Assessor, Energy Expert,Energy Manager, Author of Energy Management Books, Podcaster and an established Energy Manager Trainer.
kVA stands for kilo Volt Amps, and is used to refer to the measurement of power in a transformer or from a generator. It is as a result of the product of voltage and power. The kilo Volt Amps is mainly used for the purpose of showing the output capacity in a generator. This is important within buildings to understand the availability of energy coming into the property.
As an Energy Manager we focus on and manage energy through Kilowatts (kW) When this is reviewed over time this equates to Kilowatt Hour (kWh) and this gives us the consumption. kVA is placed second and often overlooked, if we focus on this area there are considerable savings to be made, but if we neglect this area there is significant costs. This is apparent in the larger properties and highlighted in the billing.
We have two areas of power both Actual and Apparent which are explained as follows.
Actual Power
Therefore, we can refer to kW as actual power, it is the amount of power that is converted into an output. kW x Time gives us kWh.
Apparent Power
This is known as Kilovolt Amperes (kVA) this is the measurement of apparent power. It describes the total amount of power being used by a system.
If the power factor is recorded, we then know how we can understand how to convert the kVA to kW because you know the efficiency level of the electrical system in question.
Electrical efficiency is usually expressed as a power factor in between 0 & 1, therefore the closer the power factor is to 1, then the more efficiently the kVA is being converted into actual kilowatts.
The kVA to kW and kW to kVA Formula:
1. The formula for converting
Apparent power (kVA) x power factor (pf) = actual power (kW)
e.g. 100 kVA x 0.8 = 80 kW
2. The formula for converting kW into kVA is:
Actual power (kW) / power factor (pf) = apparent power (kVA)
e.g. 80kW /0.8 = 100kVA.
Note: We also have Reactive Power is the resultant power in watts of an AC circuit when the current waveform is out of phase with the waveform of the voltage, usually by 90 degrees if the load is purely reactive, and is the result of either capacitive or inductive loads. Which Will be covered within another Article.
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4 年Very nice article Paul. It has revised basic electrical engineering ???? I am following other blogs too
Managing Director at Halstead Energy Ltd & V R Energy Ltd
4 年The savings can be huge I recently saved one of my customers ￡37,500 a year by amending their capacity allowances to something more realistic
Director of Fine & Country Central London
4 年Paul Webb is my own residential property affected by KVA?
Working in training to improve standards in FE and HE.
4 年Glad you raised this in a short but very concise post. Power Factor is widely misunderstood these days and many believe it is a method of soft starting motors. It is a fact (as I understand it) that the greater percentage of inductive loads in businesses and industry are running at low Power Factor. This is (possibly) because motors have been purchased that are too big for the loads they drive. Change of use of buildings (and therefore electrical loadings) do not take future uncorrected Power Factor into account. So it goes on. I had to know ALL about this subject as a young man and then some. In one small business I worked in, a visitor from the electricity supplier turned up and told me that Power Factor was very low. I checked the switch room and looked at the panels and found the little cubicle marked "Power Factor Correction Equipment" on it. It had been turned and left off, and had the internals part savaged sufficient to make it ineffective. The dust on the lever told me how long it had been out of circuit. There's the attitude.
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4 年Great post Paul!