The following test data are taken on a 20-hp, 250- V, 600-r/min dc shunt motor: Rf = 150 Ω, τf = 0.5 s, Ra = 0.15 Ω, and τa = 0.05 s. When the motor is driven at rated speed as a generator with no load, a field current of 2 A produces an armature emf of 250 V. Determine the following:
(a) Lf, the self-inductance of the field circuit.
(b) La, the self-inductance of the armature circuit.
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(c) The coefficient K relating the speed voltage to the field current.
(d) The friction coefficient BL of the load at rated load and rated speed, assuming that the torque required by the load TL is proportional to the speed.