a) Efficiency Calculation:
General Rule of Thumb: At 6 cents per KWh it cost $1.2 per day per horsepower to run standard efficiency motor.
It cost $1.16 per day per horsepower to run premium efficiency motor.
You save $21.90 per year per horsepower with premium efficiency motors
Based on 88% efficiency vs. 92% efficiency 24 hrs per day

Click here to download motor efficiency comparison calculator

b) Load Sharing of 2 Motors:
Load sharing between 2 motors can be evaluated using the Load Sharing calculator. Download it here.There are many factors which influence load sharing. One of the most important factors is belt slip. This "calculator" ignores slip, differences in sheave diameters etc. For this reason, it is important to make sure that the belt setup is precise. Synchronous type belts, which don't slip are often better suited to load sharing situations than "V" type belts.

c) Common Formulas:
Electrical formulas and Rules of Thumb, click here.