Tools
Motor Size
Find the standard NEMA motor size needed for a given total lift and flow rate. Results update as you type.
Inputs
Results
Water HP(HP)
3.60
Assumed OPE(fraction)
0.50
Shaft HP Needed(HP)
7.20
Motor Size(HP)
7.5
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How the motor is sized
The motor size is the smallest standard NEMA size that meets the shaft-power requirement at its efficiency. Shaft HP = water HP ÷ OPE, where water HP = total lift × GPM ÷ 3960 and the overall plant efficiency (OPE) assumed for each motor size is:
| Motor size (HP) | Assumed OPE |
|---|---|
| 5 – 7.5 | 0.50 |
| 10 – 20 | 0.55 |
| 25 – 60 | 0.60 |
| 75 – 100 | 0.65 |
| 125 – 150 | 0.69 |
| 200 – 300 | 0.70 |
| Above 300 | 0.70 |