a numerical to be solved plz!

[SliferTheSkyDragon]

Two adjustable speed drives (separately excited dc motors) have maximum speeds of
1000 and minimum of 500 rpm. Speed adjustment is obtained by field flux
control. Motor A drives a load requiring constant developed power over the

speed range and motor B drives a load requiring constant torque. All losses,

armature circuit resistance drop and armature reaction may be neglected.
If the developed power is

(a) equal at 1000 rpm and armature curreńts are each 200A, what will be thè
amature currents at 5OO rpm? ,

(b) equal 'at 500 rpm' and armature currents are each 800 A, what will be the
armature currents at 1000 rpm?

 

[ud23]

http://zone.ni.com/devzone/cda/ph/p/id/46

i don't get your exact question but you can look above link it might help you

 

[SliferTheSkyDragon]

i have edited the post! sorry!

 

[ahsan_i_h]

For field flux control method,
Both motor's armature voltage is constant,so for constant power motor A, its current will be always constant. Because V*I=constant. Now to think about costant torque motor B, its armature current is inversly propotional to field flux.Why?because, armature current*field flux=torque=constant. Now,

a) At 500 RPM field flux is doubled. Motor A current is constant so it is 200A. Motor B current is 100A(field gets doubled so armature current is half to make torque constant)
b) At 1000 RPM field flux is half. Motor A current is constant so it is 800A. Motor B current is 1600A(field gets half so armature current is doubled to make torque constant)