“CALCULATE MOTOR POWER (KW) FOR A CENTRIFUGAL PUMP”
“FORMULA”
1. (PH) HYDRALLIC POWER FOR CENTRIFUGAL PUMP IN KW
= Q (FLOW M3/HR) X PUMP HEAD (MTRS) X DENSITY OF FLUID (KG/M3) X 9.81/3600000
2. (PS) SHAFT POWER FOR CENTRIFUGAL PUMP IN KW
=HYDRALLIC POWER FOR CENTRIFUGAL PUMP (KW) X EFFICIENCY OF THE PUMP/100
3. (MP) MOTOR POWER OF CENTRIFUGAL PUMP IN KW
= (PS) SHAFT POWER FOR CENTRIFUGAL PUMP X 100/ MOTOR EFFICIENCY
EXAMPLE FOR A CASE OF COLD WATER
(PH) HYDRALLIC POWER FOR CENTRIFUGAL PUMP IN KW
Q= 200 M3/HR
H= 32 MTRS
DENSITY= 1000 KG/M3
= Q (FLOW M3/HR) X PUMP HEAD (MTRS) X DENSITY OF FLUID (KG/M3) X 9.81
3600000
=17.44 KW
(PS) SHAFT POWER OF A CENTRIFUGAL PUMP IN KW
= (PH) HYDRALLIC POWER FOR CENTRIFUGAL PUMP X 100
EFFICIENCY
EFFICIENCY OF THE PUMP = 78%
=17.44 X100
78
= 22.36 KW
(MP)MOTOR POWER OF CENTRIFUGAL PUMP IN KW
= (PS) SHAFT POWER FOR CENTRIFUGAL PUMP X 100
MOTOR EFFICIENCY
EFFICIENCY OF THE MOTOR = 94%
= 22.36 KW X 100
94
= 23.78 KW
FINALLY WE REQUIRED 25 KW MOTOR FOR DIRECT COUPLED PUMP.
IMPORTANT POINTS TO CONSIDER FURTHER
*WE REQUIRES 25 KW MOTOR FOR DIRECT COUPLED PUMP.
*IF WE ATTACH VFD TO THIS MOTOR THEN WE NEED VFD CLASS MOTOR AND WITH 20% MORE POWER SO THAT WE COULD RUN IT UPTO 60 FREQUENCY IF REQUIRED
= 23.78 KW X 1.20 = 28.5 KW
*IF WE ATTACH REDUCTION GEAR TO THIS MOTOR THEN WE NEED 20% MORE POWER = 23.78 KW X 1.20 = 28.5 KW
