Load Calculation


I proposed to install 4HP air cond., 6HP air cooled room and 10 nos

1x36W flo. light in my workshop. My calculation is to get the connected load (CL) and Total connected load (TCL) as below; am I do the right way? Pls advice. (a)4HP air cond; CL1=4HP X 746W=2984W=3kW (b)6HP air cooled; CL2=6HPX746W=4476W=4.5kW (c)10nos 1x36W; CL3=10X1X36W=360W=0.4kW (d) TCL=CL1+CL2+CL3=7.9kW. I need to work out with proper load calculation to avoid unexpected happen in electricity supply due to over load.


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Although I have a PE, I never did much of this kind of calculation to make a living. I have to get back to fundamentals.

Your conversion from horsepower to watts is correct but does not consider the efficiency of your motors and other equipment. Moreover, you did not consider power factor. You really should think in terms of the required volt-amperes rather that true power required. Efficiency and power factor requires increase in the current required to run your equipment. For equipment like fluorescent tubes, rectifiers, and the like, power factor can also be reduced because of harmonics introduced by nonlinearities. In your example, the lighting load is relatively low so that it probably is not much af a problem.


Reply to
Salmon Egg

For flourescent light we use the nameplate ampere rating on the ballasts. For motor load calculations we use the nameplate full load amperes.

A general rule for motors is to use 1 kw per 1 hp, if only hp is known.

Reply to
Gerald Newton

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