Question

A 210 V, 1200 rpm, 10 A separately excited motor is controlled by 1-
phase fully controlled converter with an ac source voltage of 230 V,
50 Hz. Assume that sufficient inductance is present in the armature
circuit to make to motor current continuous and ripple free for any
torque greater than 25% of rated torque, and Ra = 1.5 Ω.
i. What should be the value of the firing angle for the rated torque at motoring +ve (1200rpm)
ii. Compute the firing angle for the rated braking torque at (-1200) rpm
iii) Compute the firing angle at braking operation for the rated
torque at +ve (500 rpm)

Note: I'm having trouble to understand the formula va=iara+ea when the quadrant changes. I have noticed that the sign keep changing. Please don't skip the part when calculate involving the formula as stated above. thank you.

Answer 1

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