Generator Power Calculator

If you require any assistance with this power calculator or what generator will best suit your requirements, do not hesitate to contact us.

Guide to Units

HP = Horsepower
kW = Kilo Watts
kVA = Kilo Volt Amps
I = Ampere or Current
V = Volts
PF = Power Facto

Calculating Ampere (I), given kVA

Phase (1, 2, 3) Generator kVA Volts Required = Ampere (I)

Converting kVA to kW

kVA = kW

Converting kW to kVA

kW = kVA

Converting kW to HP

 kW = HP

kVA Required to run motors

What size genset is needed to start a 3 phase electric motor Direct on Line (DOL) start

HP of Motor = Generator kVA Required

Generator Size to Start Motors

Instructions: Fill in the HP of the motor(s) in their starting sequence, select the start method (DOL - Direct On Line or Star Delta) and press Calculate. The required generator size will then be displayed at the bottom.

Starting Sequence Motor HP Start Method (DOL / StarDelta) Run Variable Phase Current Starting Value Total Run Current Total Start Current
1
2
3
4
5
6
Generator Size for Starting with: kVA*
Generator Size for Running with: kVA*
Generator Size Recommended: kVA*

* Please NOTE the above calculations are an estimate only because other factors such as site conditions, motor efficiencies and iron losses are not taken into consideration.

Please Note:

Inductive loads (typically electric motors, electric pumps, electric compressors and air conditioners) require 6-8 times more current to start than to run. Most generators can provide 100% overload for start up purposes. A 1 Hp electric motor therefore will require 3-4kVA for start up. Once the 1 Hp electric motor has started, it will only consume 1 kVA leaving a extra 2-3kVA available for other appliances.

However, the newer 'Inverter' style generators may be more efficient and capable of starting higher loads.

Generator Selection

The generator size must be equal or greater than the total consumption of all applications. The higher starting requirement must he taken into account accordingly. To maximise the generator potential, the largest electrical motor should be started on its own and further appliances should only be switched on thereafter.

Power Consumption Chart

Appliance Rated Watts (Appliances) Rated kVA (To operate appliance) Rated kVA ( To start appliance)
Air Conditioner (Evaporative model) 275-1000 0.34-1.25 1.36-5
Air Conditioner (Reverse cycle) 200-2500 0.25-3.13 1-12.5
Clothes Dryer 2400 3 3
Coffee Percolator 550 0.69 0.69
Can Opener 100 0.13 0.52
Deep Freezer 500 0.63 2.52
Disposal Unit 650 0.81 3.24
Dishwasher 1000-3000 1.25-3.75 1.25-3.75
Domestic Water Pumps 275-1000 0.34-1.25 1.36-5
Exhaust Fan 40 0.05 0.2
Food Processor 500 0.63 2.52
Floor Polisher 350 0.44 1.76
Frypan 1400 1.75 1.75
Hair Dryer 1500 1.88 1.88
Hotwater Service 2500-3000 3.13-3.75 3-13-3.75
Iron 800-1500 1-1.88 1-1.88
Kettle or jug 1600-3000 2-3.75 2-3.75
Lights 25-200 0.03-0.25 0.03-0.25
Microwave 1500 1.88 1.88
Oven 4000-8000 5-10 5-10
Radio 60 0.08 0.08
Radiator 1000-2500 1.25-3.13 115-3.13
Refrigerator (home) 300 0.38 1.52
Sewing Machine 60 0.08 0.32
Space Heater 2000 2-5 2.5
Television 75-200 0.09-0.25 0.09-0.25
Toaster 250-1250 0.3-1.56 0.3-1.56
Washing Machine 500-3000 0.63-3.75 2.52-15
Welder 140A 5000 6.25 8 min

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