Click on your IC Pump Station model below to download the simple installation instructions for your model.
Model 2A VFD (Variable Frequency Drive) Serial Instructions
Technical:
1. Calculating Pump Horsepower. Pump Horsepower needed to pump a given rate of flow (gallons per minute) at a given pressure (PSI) is determined by the formula: (GPM X PSI)/3960. This figure must be divided by the pump efficiency (expressed as a decimal). Pump efficiency information is obtained from the pump curve information published by the pump manufacturer.
Below is a typical pump curve for pumps from 5-40 HP. The vertical (y) axis is feet of head (one foot of head = 0.433 PSI) and the horizontal (x) axis is PSI. The higher the flow rate the lower the PSI and vice versa for a given horsepower. The pump efficiency depends on the rate of flow (note the efficency curve at the right of the graph. Typically pumps are selected based on the flow rate needed for the best efficiency. Higher efficiency means you pay less for power to pump a given rate of flow at a given pressure.
2. Calculating Pump Power usage.
Single Phase power: Power (in watts) = Volts X Amps X Power Factor*.
Three Phase power: Power (in watts) = Volt X Amps X Power Factor* X 1.73
Example: The motor in the chart below "pulls" 33 amps at 460 volts three phase. We'll use the figure of 0.85 for power factor usage of this motor at full load as noted from the graph below. The formula would be 460X 33 X 1.73 X 0.85 = 22,322 watts or about 22 kW, as can be seen on the graph below.
Estimating power costs
If you pay 10 cents per kilo watt hour (kWh) for electricity the cost to run this motor for 1 hour would be 22 X 0.10 = $2.20 per hour this motor is run at full load. With partial loads resulting either from reducing the rate of flow ("throttling" the pump by partially closing down a valve) or by reduction in speed will result in reduced power consumption. Reducing the motor speed when full capacity is not needed is much preferred because any pressure rise behind the valve (when the flow is reduced when the pump motor is running full speed) represents wasted energy.
*Power factor is phase shift that results in increased power using the alternating current waveform. One essentialy gets extra motor torque "for free" (better efficiency) using the AC waveform action. Power factor changes with motor RPM and lower motor loads (HP) net "better" power factor figures.
