7. The following table relates to the open-circuit curve of a shunt gen- erator running at 750 rev/min: 10 172 300 360 385 395 Generated voltage (V) Field current (A) 0 1 2 3 4 5 Determine the no-load terminal voltage if the field circuit resistance is 125 Q. If the speed is now halved, what is the resultant terminal voltage? At the reduced speed, what value of field circuit resistance will give a no-load terminal voltage of 175 V? (N.C.T.E.C., O.2)

7. The following table relates to the open-circuit curve of a shunt gen- erator running at 750 rev/min: 10 172 300 360 385 395 Generated voltage (V) Field current (A) 0 1 2 3 4 5 Determine the no-load terminal voltage if the field circuit resistance is 125 Q. If the speed is now halved, what is the resultant terminal voltage? At the reduced speed, what value of field circuit resistance will give a no-load terminal voltage of 175 V? (N.C.T.E.C., O.2)

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...

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A shunt generator on dest is separately encited and driven at 1000 rev /min. The open circuit test chars. are given Field test CA o 0'157 O.477 0 663 O.805 1.0 129 Induced Emf CU) 12a5 300 400 100 450 500 550 ine mlc is then shunt Connected and gun at l000 revlmine with a constant field cicuit esistance of 540R. The agmature docuit resistamee is er. Deduce and plot the load Chargaetesistics of this mle,negleeting effeetof amarterre reaction.what is value of manimum lbud cursrent.
Q7/ A separately excited DC motor has the following parameters: Ra = 0.3 2, Ke = 0.52 V/rpm.Wb, d (flux per pole) = 150 mWb. The motor speed is controlled by a full wave bridge 'rectifier. The firing angle a is set at 30°, and the average speed is 1500 rpm. The applied a.c. voltage to the bridge is 440 V at 60 Hz. Assuming the motor current is continuous; calculate the armature current drawn by the motor and the steady-state torque for the cases of: (a) half-wave converter (b) Fully- controlled bridge
For a 18600W 2400rpm DC motor, the following values are given: Ra = 0.089 2 (value at room temperature (250C)), La = 0.00144 H, KT = 0.85 Nm / A and KV = 0.851 V / (rad / s)), (In calculations Use the hot resistance values at 1000C.) (Take the rated field winding losses as Wf= 210W.) If this DC machine is operating as a motor with rated flux at rated speed, calculate the rated torque (TR), rated current (IR), rated voltage (VR), efficiency (n) at the rated point, taking into account the winding losses. Find the speed (@NL) of this motor in no-load condition. TR Nm IR А VR V Eff = % ONL= rpm
QUESTION 3 а) Describe a static energy component in power electronics fundamental. A single-phase full-wave ac voltage controller working on the ON-OFF control technique b) has a supply voltage of 230 V (RMS) 50 Hz with a purely resistive load that is connected in series as of 35 N and 10 Q. The controller is set to ON-mode for 40 cycles and off for 20 cycles. i) Justify whether the converter is operating at the optimum duty cycle (k) of> 50%. ii) Analyse the capability of the converter in supplying the load at 180 V (RMS).
re ot t 6.10 A DC chopper is used in regenerative braking mode of a dc series motor. The dc supply is 600 V the duty cycle is 70%. The average value of armature current is 100 A. It is continuous and ripple free. What is the value of power feedback to the supply? (a) 3 kW (b) 9 kW (c) 18 kW (d) 35 kW
A single phase full wave AC voltage controller supplies resistive load R = 10 2. The input supply voltage is 120 V, RMS at 60HZ. The controller is ON for 25 cycles and off for 75 cycles. Calculate: 1- RMS output voltage. 2- Input P.F.
A 0,9 kW DC shunt motor is loaded by a constant torque of 12 Nm. The armature resistance of the motor is 5 Ω, and the field constant KØ = 3 Vs/rad. The motor is driven by a half wave thyristor converter. The power source is a 140 V, 50 Hz. The triggering angle of the converter is 450 and the conduction period is 1650 . Calculate the motor speed and the developed power.
7. The following table relates to the open-circuit curve of a shunt gen- crator running at 750 rev/min: Generated voltage (V) Ficld current (A) 10 172 300 360 385 395 0 1 2 3 4 5 Determine the no-load terminal voltage if the field circuit resistance is 125 N. If the speed is now halved, what is the resultant terminal voltage? At the reduced speed, what value of field circuit resistance will give a no-load terminal voltage of 175 V? (N.C.T.E.C., 0.2)
7. The following table relates to the open-circuit curve of a shunt gen- erator running at 750 rev/min: Generated voltage (V) Field current (A) 10 172 300 360 385 395 0 1 2 3 4 Determine the no-load terminal voltage if the field circuit resistance is 125 N. If the speed is now halved, what is the resultant terminal voltage? At the reduced speed, what value of field circuit resistance will give a no-load terminal voltage of 175 V? (N.C.T.E.C., O.2)
A de machine is controlled by the step-down de-de converter shown below. The armature inductance La =0.2 mH and the armature resistance can be neglected. The armature current is 5A. The Buck converter is operating at the switching frequency is 30 kHz and the duty ratio is 0.8. L₁ + Answer the following questions: 1) Calculate the input voltage (Va) if the output voltage (ea = 200 V). 2) Find the ripple in the armature current (a). 3) Calculate the maximum and minimum values of the armature current (la). 4) Sketch the armature current (ia (t)) and the supply current (id (t)).
An armature controlled DC motor has the following parameters: Tf = 0.03 Nm KT = 0.15 Nm/A Imax = 2.4 A KĘ = 0.15 Vs/rad Wmax = 5000 rpm R = 0.8 Ohms 1. Determine the following: (i) The maximum output torque. (ii) The maximum power output. (iii) The maximum armature voltage. (iv) The no load motor speed when e = Emax 2. Plot the following relationships: (i) Torque versus current (ii) Induced voltage versus speed 3. If the above motor is operated at 3000 rpm with a load torque of 0.15 N.m, determine the armature voltage
Two shunt generators A and B operate in parallel and their load characteristic s may be taken as straight lines. The voltage of A falls from 240 V at no - load to 220 V at 200 A, while that of B falls from 245 V at no - load to 220 V at 150 A. Determine the current which each machine supplies to a common load of 300 A and the bus - bar voltage at this load.