5 replies to this topic

[ron23]

Good day!

 

I am currently evaluating if the driver (electric motor) of a pump was sized correctly in terms of electric motor power output. I already computed the power requirement of pump at rated capacity. In line with this, what factors do I need to multiply with the power requirement to calculate the required electric motor power output?

 

In one literature that I have read, power requirement is multiplied by service factor and safety factor (set by American Petroleum Institute for refinery applications) to compute for the required electric motor power output. I would just like to know if this is true?

 

Thank you.

[Prasanjit]

Yes , if you go as per API 610 to calculate the power of the motor / driver, you would get the nearest exact power motor/driver.

[ankur2061]

ron23,

 

After you have calculated the  BkW (Brake kilowatt) of the motor using the formula:

 

BkW = Q*ΔP / (36*Eo)

 

where:

 

BkW = Brake Kilowatt in KW

Q = Volumetric flow rate in m³/h

ΔP = Differential Pressure, bar

E_o = pump hydraulic efficiency

 

The BkW obtained thus needs to be multiplied by a load factor to arrive at the motor power. Load factors are typically 1.1 for centrifugal pumps and 1.05 for positive displacement pumps. Next round-off (round-up) the motor power to the next available standard motor size.

 

Regards,

Ankur.

Edited by ankur2061, 27 February 2014 - 12:08 AM.

[breizh]

ron 23,

 

On top of what is written above , consider this resource ( last pages with reference to ABB motor) with power factor indicated # 0.9

Hope this helps

 

Breizh

[gegio1960]

 sizing of electric motors for pumps.xlsx   27.73KB   93 downloads

[gegio1960]

added the calculation of an estimate of the pump efficiency

 

 

 sizing of electric motors for pumps_r1.xlsx   28.26KB   86 downloads