Submersible Pump Full Load Current

measure output pressure and rate of flow(H&Q) and check the kW from manufacturer's pump curves.

As one cannot see the direction of rotation of a submersible pump,run it in both directions and take valve shut off and fully open currents.The current corresponding to higher pressure is running current if pump and motor and coupling are ok.Check with nameplate rating or if nameplate missing contact manufacturer. If measured current is higher than nameplate close/throttle slightly.

First turn off the all-caps.

Same as any other 3-phase motor

Let us say it is a centrifugal pump [usually].There is three types:

Radial Flow Pump, Mixed Flow Pump, Axial Flow Pump

You have to calculate the brake HP [BHP]:

BHP=GPM*Head*Sp.Gr/3960/efficiency where:

GPM=gallons per minute [the liquid flow]

Sp.Gr=specific gravity of the liquid

Head [ft.] including conduit friction and static head [up to the tank-for instance].

See-for instance:

www.pacificliquid.com/pumpintro.pdf

www.gouldspumps.com/cpf_0009.html

According to BHP and pump rated rpm [and your supply voltage] you will choose your motor and the rated current you will see in the catalogue.

use the details on the motor nameplate. There is no other way you can calculate what protection to use, size your cable etc.

You can do the mechanical sums working out flow etc but a simple ammeter has to be easier.

At startup you would expect the current to be about 6 times FLC for a second or so.

Kw = E I √3 cosφ / 1000 η. In the absence of information, estimate cosφ = η = 0.90; rearrange terms, and calculate I.

Oh, any number of ways:

• Measure it with a tong-tester.
• Look it up in the pump manufacturer's published performance information.
• Look it up in the manufacturer's user manual supplied with it.
• Take the flowrate through the pump, multiply by the pressure rise through the pump, divide by the motor-pump overall efficiency, and divide by the applied voltage.
• Pick up the telephone and speak to the pump manufacturer's technical helpline direct with the pump and motor serial numbers to hand.
• Discuss the need for the pump with the pump manufacturer's technical sales representative.
• Any combination of the above.