A 25-KW, 125 V separately excited DC machine is operated at constant speed of 3000 rpm with a constant field current suc

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A 25 Kw 125 V Separately Excited Dc Machine Is Operated At Constant Speed Of 3000 Rpm With A Constant Field Current Suc 1 (37.17 KiB) Viewed 47 times

A 25-KW, 125 V separately excited DC machine is operated at constant speed of 3000 rpm with a constant field current such that the open-circuit armature voltage is 125V. The armature resistance is R₂ = 0.15 2 and the armature inductance is L. = 20 mH.. (a) Determine the starting current if no starting resistance is used in the armature circuit (b) Propose a DC motor starter box to restrict the starting current to twice the rated current of the DC motor and plot the armature current during the starting process. (c) The speed of the separately excited dc motor is controlled by a single-phase full converter. The ac supply voltage is 220 V. The motor voltage constant is K₂ = 0.33 V/rpm. Assume that motor current is continuous and ripple-free. For a firing angle a = 45° and rated motor current, determine the: i. Speed of the motor. ii. Motor torque. Power to the motor