A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 &ohm; and armature current is 10 A. If the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armat

1.	A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 &ohm; and armature current is 10 A. If the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be
A.	1.79 &ohm;
B.	2.1 &ohm;
C.	3.1 &ohm;
D.	18.9 &ohm;
Answer» B. 2.1 &ohm;

Discussion

No Comment Found

Related MCQs

A single phase 10 kVA, 50 Hz transformer with 1 kV primary winding draws 0.5 A and 55 W, at rated voltage and frequency, on no load. A second transformer has a core with all its linear dimensions 2 times the corresponding dimensions of the first transformer.The core material and lamination thickness are the same in both transformers. The primary windings of both the transformers have the same number of turns. If a rated voltage of 2 kV at 50 Hz is applied to the primary of the second transformer, then the no load current and power, respectively, are
A synchronous motor is running from an infinite bus of voltage V1 in steady-state, at about 50% of its rated load with a power-angle 1 between Vt and Ef (induced voltage). The load is suddenly decreased to 25%. Ef attains its new steady-state power angle 2 with Vt by initially
A single-phase transformer is feeding a lagging load. What will be the effect on t he voltage regulation of the transformer if (i) an inductor is connected in parallel to the load (ii) a capacitor is connected in parallel to the load The regulation will
A three phase, wound rotor induction motor is to be operated with slip energy recovery in the constant torque mode, when it delivers an output power Po at slip s. Theoretically, maximum power available for recovery at the rotor terminals, is
Two coupled dc series motors with constant torque load are changed over from series to parallel connection across a fixed volt age supply. As compared to the original speed the set speed
A dc series motor has linear magnetization and negligible armature resistance, the motor speed is where, T = load torque
A synchronous generator is feeding a zero power factor (lagging) load at rated current.The armature reaction is
A 400 V, 50 Hz, three phase balanced source supplies power to a star connected load whose rating is 12 3 k VA, 0.8 pf (lag). The rating (in kVAR) of the delta connected (capacitive) reactive power bank necessary to bring the pf to unity is
A 3 phase, 10 kW, 400 V, 4 pole, 50 Hz, star connected induction motor draws 20 A on full load. Its no load and blocked rotor test data are given below : No Load test : 400V 6 A 1002 W Blocked Rotor test : 90 V 15 A 762 W Neglecting copper loss in no Load test and core loss in Blocked Rotor test, estimate motor 's full load efficiency.
A 3 phase, 4 pole, 400 V, 50 Hz, star connected induction motor has following circuit parameters r1 = 1.0 &ohm; , r2' = 0.5 &ohm; x1 = x2' = 1.2 &ohm;, xm = 35 &ohm; The starting torque when the motor is started direct- on-line is (use approximate equivalent circuit model)

A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 &ohm; and armature current is 10 A. If the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be

Discussion

No Comment Found

Related MCQs

Reply to Comment