How can I calculate the Fan Discharge (m3/min) if I change the frequency from 50 Hz to 40 Hz ?
I have one query about Centrifugal FAN..
Basic : I have an VFD driven Motor linked with Fan with Belt and Pully system and if…
Air Quantity : 1000 (m3/min)
Static Pressure : 120 mm Wg
Frequency : 50 Hz
Question : Now How can I calculate the Discharge (m3/min) if I change the frequency from 50 Hz to 40 Hz ?
As a first approximation Steelpump is correct the output flow of a blower or fan is porportional to the speed of the motor, but it is not entirely linear. See the sample data sheet for a blower with both 50Hz and 60 Hz power.
The change in frequency – 50/60 = 0.833
The change in speed – 2750 / 3050 = 0.901
The change in output at free flow – 68/73 = 0.932
Remember the flow rate will increase by the square in the increase in pressure.
Niel
I’ve not dealt much with AC powered fans, but I did a search and found this link: http://www.rexelarchive.com/drupal-4.4.2/node/view/183
So using the formulas they provided, I believe you can determine the ratio of work output by the fan motor due to the change in frequency.
I’m sure some electrical engineers around here could explain better (it’s been a looonnggg time since I took my E.E. classes).
dear sir,
it is very simple .. quantity of flow is depend upon speed of equipment.
N1/N2 = Q1/Q2
NI is speed at 50 hz and N2 is speed at 40 Hz
Q1 is discharge at 50 hz
so Q2 = N2 x Q1 /N1
but your pressure will also come down drastically as per following formula
N1 X N1 /N2X N2 = P1/P2
HOPE THIS WILL SOLVE YOUR PROBLEM
