Please help

Thread Starter


Joined Jul 10, 2007
Hi, I am doing some studying but I'm very stuck.

My question is, I have a 30W, 200V, 800rpm dc motor connected to a 230V single phase, 50HZ line using a bridge converter. The full load armature current is 150A and the armature resistance is 0.06 Ohms.

I have worked out the firing angle under rated full load like this:


So Vd/(0.9*VRMS) = 200/(0.9*230) = .96 ArcTan = 15 degrees.

The thing I'm stuck on is hoe to calculate the firing angle required so that the motor developes its rated torque at 400rpm.

Please could anyone help?