Q3 A 120 HP DC shunt motor is connected to a voltage supply of 240 V. The armature draws a nominal current of 400 A. The motor is currently running at 800 rpm and it is required to stop this motor using dynamic breaking method. a) Calculate the breaking resistance required such that at the instant of breaking the armature current does not exceed 125 % of nominal armature current. b) Calculate the time constant, To, if the moment of inertia is 300 Kg.m² with the breaking resistance you found in part (a) above.

Q3 A 120 HP DC shunt motor is connected to a voltage supply of 240 V. The armature draws a nominal current of 400 A. The motor is currently running at 800 rpm and it is required to stop this motor using dynamic breaking method. a) Calculate the breaking resistance required such that at the instant of breaking the armature current does not exceed 125 % of nominal armature current. b) Calculate the time constant, To, if the moment of inertia is 300 Kg.m² with the breaking resistance you found in part (a) above.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

See similar textbooks

Similar questions

Q2/A synchronous motor having 60 % reactance and a negligible resistance is to be operated at rated load (i) u.p.f. (ii)0.6 p.f. lag (iii) 0.6 p.f. lead .What are the values of e.m.f. ? Indicate assumptions made ,if any.
i need the answer quickly
q3a as ap
A 55 hp, 440 V, 400 rpm DC shunt motor draws 107 A when operating at rated conditions. The motor has an armature-circuit resistance of 100 mW and a total field-circuit resistance of 55 W. Draw a schematic of the motor in the space below showing all known quantities (resistances, currents, voltages and load). Show only symbols for unknowns.
A 200 V series DC motor with the magnetization curve as shown in Figure Q1(a) has a field winding of 25 turns per pole. Its armature resistance is 0.05 2, and its field resistance is 0.05 2. The armature current is set to 50 A. (i) Based on the given specification, sketch the equivalent circuit of the DC motor. (ii) Calculate the speed and induced torque of the DC motor. (iii) Calculate the output power and efficiency of the DC motor. Rotational speed = 1200 rpm 200 - - 175 - 150 -- 125 100 75 50 25 1000 2000 3000 4000 5000 6000 7000 Field magnetomotive (A.turns) Figure Q1(a): Magnetization curve Internal generated voltage, EA (V)
600V, DC series motor operates at 600 rpm and rated load. Armature resistance 0.1 ohm and series fieldwinding resistance is 0.05 ohms. At full load, the motor draws 195 A current. A) Find the reverse(back) EMF value at full load. B) Find the power and internal moment produced in the armature under full load.
DC Electric Machine: Working in a constant voltage and frequency network. A synchronous motor with a constant excitation current does not work at idle and as a motor. What happens when the mechanical load on the motor shaft is increased?1) Armature current increases.2) Armature current decreases.3) The load angle decreases.4) The load angle increases.5) Power factor switches to inductive.6) Power factor switches to capacitive.
The armature resistance of a 250 V D.C. shunt motor is 0.5 Ω. The minimum and maximum current during starting are 50.25 A and 67 A respectively. Determine the number of sections of the starter and resistance of each section..
power electronics and drives
answer part d only
At full load, when the DC shunt motor is supplied by 110 V dc source, the armature current is 20 A keeping the speed of the motor at 500 rpm. If the flux of the motor is weakened by 10%, the armature current drops to 15 A. By how much is the torque decreased?
the BLDC motors have the advantage of High Efficiency Compactness Low Maintenance All of the answers When the speed of the DC motor is Increases its Armature current Remain Constant Decreases Increases Any of the answers A variable reluctance stepper motor is constructed of .. . material with salient poles. ferromagnetic paramagnetic non-magnetic diamagnetic