- Amperes when kVA is known
- Converting kVA to kW
- Converting kW to kVA
- Converting kW to HP
- kVA Required to run motors
Calculating Ampere (I), given kVA
Converting kVA to kW
Converting kW to kVA
Converting kW to HP
kVA Required to run motors
What size genset is needed to start a 3 phase electric motor Direct on Line (DOL) start
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.
* 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.
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.
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|
|Domestic Water Pumps||275-1000||0.34-1.25||1.36-5|
|Kettle or jug||1600-3000||2-3.75||2-3.75|
|Welder 140A||5000||6.25||8 min|