Calculators › Operations, maintenance and commissioning Pump excess electrical input calculator
Pump excess electrical input
Compare metered input with the accepted clean electrical input at the same required hydraulic duty. Wire-to-water efficiency already includes pump and motor losses.
Units IP (US) SI (metric)
P excess = P meter − 0.746 × Q × H 3960 × η clean P_{\text{excess}} = P_{\text{meter}} - \frac{0.746 \times Q \times H}{3960 \times \eta_{\text{clean}}} P excess = P meter − 3960 × η clean 0.746 × Q × H P excess = P meter − 9.81 × Q × H 1000 × η clean P_{\text{excess}} = P_{\text{meter}} - \frac{9.81 \times Q \times H}{1000 \times \eta_{\text{clean}}} P excess = P meter − 1000 × η clean 9.81 × Q × H
Calculator
Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.
Worked example
Given
P meter P_{\text{meter}} P meter 18 kW Q Q Q 500 gpm H H H 95 ft η clean \eta_{\text{clean}} η clean 0.72 fraction P excess = 18 − 0.746 × 500 × 95 3960 × 0.72 ≈ 5.572 P_{\text{excess}} = 18 - \frac{0.746 \times 500 \times 95}{3960 \times 0.72} \approx 5.572 P excess = 18 − 3960 × 0.72 0.746 × 500 × 95 ≈ 5.572
Given
P meter P_{\text{meter}} P meter 14 kW Q Q Q 30 L/s H H H 24 m η clean \eta_{\text{clean}} η clean 0.72 fraction P excess = 14 − 9.81 × 30 × 24 1000 × 0.72 = 4.19 P_{\text{excess}} = 14 - \frac{9.81 \times 30 \times 24}{1000 \times 0.72} = 4.19 P excess = 14 − 1000 × 0.72 9.81 × 30 × 24 = 4.19
Symbols and units
Symbol Meaning Unit
P excess P_{\text{excess}} P excess excess input above accepted clean duty kW P meter P_{\text{meter}} P meter measured electrical input kW Q Q Q required water flow gpm H H H required water head ft η clean \eta_{\text{clean}} η clean accepted clean wire-to-water efficiency fraction
Symbol Meaning Unit
P excess P_{\text{excess}} P excess excess input above accepted clean duty kW P meter P_{\text{meter}} P meter measured electrical input kW Q Q Q required water flow L/s H H H required water head m η clean \eta_{\text{clean}} η clean accepted clean wire-to-water efficiency fraction
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