Performance of irrigation pumps:

1. Watt horse power (WHP):

• It is the horse power required for pumping.

WHP = QH/ 76

Where, Q = discharge, l/s.

             H = Total head , m

OR,

WHP = QH/273

Where, Q = m³/hr

            H = m

2. Shaft Horse power (SHP):

• It is the power required at the pump shaft.

SHP = WHP/ η_p

Where, η_p = pump efficiency

Note: SHP> WHP (Always).

3. Pump efficiency (η_p):

Pump efficiency (η_p) = Output power/ input power  = WHP/SHP.

4. Brake Horse Power (BHP):

• It is the actual horse power required to be supplied by the engine or electric motor for driving the pump.

BHP = WHP / (η_p x η_d )

5. Horse power (H_p):

H_p = BHP/ η_m [ η_p  = motor efficiency]

• It can also be written as, H_p = SHP/ (η_d . η_m) = WHP/ (η_d. η_m. η_p)

5. Kw input to the electric motor :

Kw input to the electric motor = Hp input to electric motor x 0.746

                                                  = (BHP/ η_m) x 0.746

                                                  = WHP/ (η_d. η_m. η_p) x 0.746