A six-pulse SCR bridge for a three-phase source draws power from a 500 V, 50 Hz line (the volt- age is specified as the RMS line-to-line potential, as is standard in three-phase practice). The rec- tifier supplies a large dc motor. The motor has series inductance La = 0.4 mH and series resis- tance R = 5 mn. The internal voltage V₂ = kw, where k is a field flux constant equal to 3 V s/rad, and w is the shaft speed in rad/s. The shaft torque is T₂ = kia, where ia is the motor current. It is desired to operate this motor with a 250 A current limit to provide a controlled acceleration at start-up. Determine the SCR phase delay angle as a function of motor speed to enforce a 250 A current.