A 230-V d.c. series motor has an armature circuit resistance of 0.2&ohm; and field resistance of 0.1&ohm;. At rated votage, the motor draws a line current of 40 amps and runs at speed of 1000 r.p.m. What is the speed of the motor for a line current of 20 A at 230 V? Assume that the flux at 20 A line current is 60% of the flux at 40 A line current.

A 230-V d.c. series motor has an armature circuit resistance of 0.2&oh

1.	A 230-V d.c. series motor has an armature circuit resistance of 0.2Ω and field resistance of 0.1Ω. At rated votage, the motor draws a line current of 40 amps and runs at speed of 1000 r.p.m. What is the speed of the motor for a line current of 20 A at 230 V? Assume that the flux at 20 A line current is 60% of the flux at 40 A line current.
A.	1213 rpm
B.	1513 rpm
C.	1713 rpm
D.	1913 rpm
Answer» D. 1913 rpm

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 : <table class="wp-block-table"><tbody><tr><td>No Load test : </td><td> 400V </td><td> 6 A </td><td>1002 W </td></tr><tr><td>Blocked Rotor test : </td><td> 90 V </td><td> 15 A </td><td> 762 W </td></tr></tbody></table> 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)

Discussion

No Comment Found

Related MCQs

Reply to Comment