Demystifying The Power Industry
After working with clients from a variety of experience talking about temporary power, we decided to try and simplify the process by defining terms and giving information about what is essential information for us to provide the correct power, first time.
N.B – All calculators assume maximum draw and do not account for circuit diversity.
Ohm’s Law
Used to help understand the relationship between Voltage, Resistance and Current in an electrical circuit. Essential for designing safe circuits and predicting how a device will behave when powered. The formula can be transposed based on the information you have.
Formula: V= I * R
V = Voltage (Volts, V)
I = Current (Amps, A)
R = Resistance (Ohms, Ω)
Example:
You’d like to know how much resistance there is in a 10A circuit.
V = I * R
R = V/I
230V / 10A ≈ 23Ω
Power Formula
Tells you how much electrical energy a device/load uses. This is vital for estimating loading on a generator and understanding energy consumption for cost and efficiency. The formula can be transposed for the information you do have.
Formula: P = V x I
P = Power (Watts, W)
V = Voltage (Volts, V)
I = Current (Amps, A)
Example:
You’d like to know how much current a 3000W fryer draws.
P = I*V
I = P/V
3000W / 230V ≈ 13A
| Device | Typical Power (Watts) | Amps @ 230V |
|---|---|---|
| Kettle | 2000W | 8.7 A |
| Fryer | 3000W | 13 A |
| Fridge | 150W-400W | 0.7-1.7 A |
| PA System | 500W-2000W | 2.2A-8.7 A |
| Lighting Rig | Varies Widely | Depends |
Calculating Total Power Draw
Once each appliance’s power is calculated the total power draw can be calculated ready to specify a temporary supply. This is as simple as adding together all the kW ratings.
Formula:
Ptotal = P1 + P2+ P3 + P4 + …
Example:
Adding a caterer’s requirements together (3kW fryer, 2kW kettle, 2.2kW pizza oven)
3 + 2 + 2.2 = 7.2kW
Converting kW to KVA (Generator Sizing)
If your event venue doesn’t have installed power supplies available for you to use you can now calculate what size generator is required to supply the equipment you’re using. Generators are rated in kVA which is a measure of apparent power. The difference between kW and kVA is all based on the efficiencies in an electrical system which means that 10kW will never equal 10kVA. The efficiency in an electrical system is known as the Power Factor. Generators have a standard power factor of 0.8, the calculator below uses this as the Power Factor.
The kW to kVA calculator below assumes balanced loads across three phases. For example an entry of 33kW assumes 11kW of load will be on each phase.
As well as providing generators and cabling we also have a stock of Battery Energy Storage Systems that can be used alongside or instead of generators in certain circumstances. For discuss this further please contact us, or to see our full range of temporary power equipment please see our Power Stock page.
