Rules of thumb, generators and troubleshooting
RULES OF THUMB
Everyone loves those shortcuts! Rules of thumb are good for a quick estimate or a check to see if a multiplier or decimal place may have been missed. Rules of thumb are strictly shortcuts. They ignore correction factors, round off significant figures, and pay no attention to individual machine performance. Using them for engineering design calculations must be avoided.
Engine Horsepower
Engine net horsepower = 1.5 x kW of generator
Assumes approximately 0.90 generator efficiency.
Motor Starting
Gen-Set maximum across-the-line motor start = 0.5 HP per kW
Ignores differences in generators, motor code letters and types of load.
Total Motor Load
Total motor load a generator can power = 1.14 x kW
Generator kW to power motor load = 0.877 x total motor HP
Assumes approximately 0.85 motor efficiency and 0.8 power factor or better.
Sound Attenuation
Noise level reduces 6 dBA each time distance from the generator set is doubled.
