DC Motor calculation

[FARAD]

Hi
How i can calculate N(rpm),Ia(armature),If(field) of a dc motor(series and shunt)at full load and no load when supply it with a known voltage(for example 100 Vdc) if i know only its Structural specifications?(Rf, Ra, number of fields windings turn, number of armature winding turns, armature core size, field(stator) core size, core sheets B-H curv, commutator size.. etc)
(an anticipation after design and befor constraction!)

thanks for any guidance!
FARAD

 

[jbartos]

Suggestion: Visit

http://www.tpub.com/doeelecscience/

http://powerelec.ece.utk.edu/pubs/Chiasson_publications_06.pdf

etc. for more info

 

[bssrinivasa]

Mr. Farad,

Actually i am not able to understand the purpose of your question. If you are able to get values of the all the parameters, then it would be helpful.
To be frank with you, really i am not able to understand your question even though i was a designer of DC motor.

 

[FARAD]

Dear bssrinivasa

I mean: for a dc motor with a known load(and without nameplate) can you "predict" its speed and armature current after connection it to a for example 100 Vdc?...if yes..how?

however Thank you and Merry Christmas to You

dear jbartos Thank you for your helpful reply and Merry Christmas to You

 

[bssrinivasa]

Dear Farad,

1.If you know your load in kw, you can calculate armature current by assuming certain value of effeciency.

Effeciency = (Va* Ia) / kW

2. For calcuating its speed, you should know total no. of Conductors in armature. It is quite difficult to find out, without removing armature conductors. you should also know the value of operating flux. This can be estimated by conductiong o.c.c.

3. Alternative method is run your machine with your 100va. Then measure its speed at no load. If you are interested you can note down armature current under no-load condition.

3. Then you can load the machine and note down its armature current and its field current. Loading can be done, only if you know its rating of the machine or if you know what is its actual load on this machine.

4. Otherwise you should load this machine in steps to find out its capacity. Basically it involves lot of repeatative tests to find out its specification and characteristics.


Please note i have assumed your machine is a self excited machine.

 

[jbartos]

Suggestion to the previous posting: Please, would you clarify Effeciency = (Va* Ia) / kW