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Can anybody tell me whether there is any real advantage to a brushless motor rather than the older brush types? Manufacturing cost? reliability? efficiency? Thanks Shaun

for information: Centrifugal fans: backward curved blade:power rises to max at the middle of flow range then falls at highest flow rates, this is known as a non-overloading power characteristic. Paddle bladed: power rises continuously with flow forward curved blades: power rises continuously...

robram wouldn't it be easier to fit a damper in the line to give easily controllable pressure drop? You could put a pressure tapping either side of the valve / damper to attach a manometer or similar.

without getting into complicated formulas, I am not surprised at the effect you are getting: As the first vessel is compressed a flow is induced into the second vessel due to pressure difference - no problems there. The pipe which joins the two vessels will have a resistance to flow -...

momoneymo check out this link for some useful info. The site belongs to a power screw manufacturer who may be able to give you more details: http://www.roton.com/application.1.jsp#5 Regards Shaun.

to Rbulsara Yes I agree, my statement wasn't correct, I should have said efficiency is reduced not power output. Thanks Shaun

Page 1706 of the 26TH edition gives an overview of applications.

Refer to: http://www.lima-int.co.uk/whatispfc.htm The web page above refers to the 'wasted' emf production power as KVAR or Reactive Power:- "The KVARs required for an induction motor are the same whether the motor is loaded or not. Therefore when the motor is not loaded the power factor is...

Thanks Guys I think I have it now: For purely resistive loads the power factor is 1. This means that VI in = KW out. For motors there is some inductive load (which is work done to maintain magnetic field) The inductive load pulls the voltage and current out of phase so for any instantaneous...

Can anybody give a brief practical explanation of motor power factors / phase diagrams etc. This is my understanding so far: for a purely inductive load the current peaks 90 degrees after the voltage peak on the sin wave and this would give a power factor of 1. The problem is that motors aren't...

hoop stress (in Pa) = PD/2T P=Pressure (Pa)= 75*10^6 Pa D = nominal diameter of hoop / cylinder in metres T = thickness of cylinder wall in metres This works for thin walled cylinders, diameter to wall thickness ratio 20:1(ish)(for thick walled cylinder you want a formula called Lame's...

electricpete with respect to your question about fans: They generally behave in a similar way to pumps because the work at low pressures (usually) and so the air behaves as an incompressible fluid. The info I have is as follows: Centrifugal fans: backward curved blade:power rises to max at the...

I would do the following for check of efficiency: 1)with pumps running measure flow and outlet pressure where pump outlets combine. This will probably be the difficult bit if you dont have instrumentation! 2)Using SI units multipy pressure by flow i.e m3/s * Pa = Watts (work being done) NB...