Q3. A four-pole de machine has an armature radius of 12.5 cm and an effectivelength of 24 cm. the poles cover 80% of the armature periphery. The armaturewinding is double-layered and has 33 coils. Each having 6 turns. The averageflux density under each pole 0.78 T. for a lap-wound armature winding,determine:a) The machine constant.b) The induced armature voltage when the armature rotates at 860r/m.c) The electromagnetic torque developed when the current in the coil is 60 A.d) The power developed by the armature.Q4. Answer the following:1- Does the voltage regulation of transformer became zero ?When and Why?Draw the phasor diagram of this case.2- What are causes of failure to excite self-excited de generator.a- Zero reading on voltmeter after rotating armature.b- Voltmeter reading decrease rather than increase as generator is started.c- Voltmeter shows zero reading.d- This wipes out the residual flux and fails to excite.Q5). Put (T) for true sentences and (F) for fouls one of all the followingsentences and (correct the fouls sentences):1) The open circuit terminal voltage of DC self-excited generators can becontrolled by controlling armature current.2) In relation to a transformer, the ratio 20 : 1 indicates that for every (20)twenty turns on primary, there is (1) one turn on secondary.3) If a self-excited d.c. generator after being installed, fails to build up on itsfirst trial run, the first thing to do is to reverse field connections.4)No-load test on a transformer is carried out to determine copper loss.5) If residual magnetism of a shunt generator is destroyed accidentally, it maybe restored by connecting its shunt field to a d.c. source.

As per our guidelines we are supposed to answer only one question. Kindly repost other questions as…

Q3. A four-pole de machine has an armature radius of 12.5 cm and an effective length of 24 cm. the poles cover 80% of the armature periphery. The armature winding is double-layered and has 33 coils. Each having 6 turns. The average flux density under each pole 0.78 T. for a lap-wound armature winding, determine: a) The machine constant. b) The induced armature voltage when the armature rotates at 860r/m. c) The electromagnetic torque developed when the current in the coil is 60 A d) The power developed by the armature.

Q3. A four-pole de machine has an armature radius of 12.5 cm and an effective length of 24 cm. the poles cover 80% of the armature periphery. The armature winding is double-layered and has 33 coils. Each having 6 turns. The average flux density under each pole 0.78 T. for a lap-wound armature winding, determine: a) The machine constant. b) The induced armature voltage when the armature rotates at 860r/m. c) The electromagnetic torque developed when the current in the coil is 60 A d) The power developed by the armature.

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

An electromagnet has a movable iron part and dimensions of magnetic circuit with uniform cross section as shown in figure. The core is made of ferromagnetic material with relative permeability of 3000: a) b) c) Calculate the magnetic reluctance of the circuit and the inductance of the main winding. Determine the air-gap flux, the flux density and the field intensity of the core and gap. Because of a fault in the power supply, the exciting current is increased to 8 A causing the mobile element of the iron core to move to a zero gap position as a result of the excessive electromagnetic force action. If this movement occurs in 0.01 s, find the transient voltage induced in the test coil having two turns. 0.5 mm air-gap 2 cm 2 A 3 cm 2 cm 60 turns 18 cm test coil 24 cm 0.5 mm air-gap
An 8 pole, lap-wound armature has 1200 conductors and a flux pole is 0.06wb. Determine the emf generated when the dc machine running at 600 rev/min.(CLO2)
Q3) The armature of a 4-pole DC machine has 240 coils wound in lap formation. Each coil generates a voltage of 4 V and carries a current of 5 A. a) Calculate the total generated voltage in the armature,Eg. b) Find the current in each parallel path and total armature current. c) If the armature is rewound in wave formation, find the generated voltage, Eg, current per path and total armature current. Assume number of coils are fixed at 240.
SOLVE AND SHOW YOUR COMPLETE SOLUTION. ANSWERS SHOULD BE IN TWO DECIMAL PLACES. The armature of a two-pole dc machine has 30 slots, each slot has 4 conductors each. during its operation, only 75% of the conductors are directly under the pole. each pole measures 2 inches by 3 inches and produces ten million maxwells of flux. the armature core is 12 inches in length and 3.5 inches in diameter. the total resistance of the winding is 2 ohms. e) Determine the total torque exerted by the armature core in ft - lb if the winding is simplex lap winding.
SOLVE AND SHOW YOUR COMPLETE SOLUTION. ANSWERS SHOULD BE IN TWO DECIMAL PLACES. The armature of a two-pole dc machine has 30 slots, each slot has 4 conductors each. during its operation, only 75% of the conductors are directly under the pole. each pole measures 2 inches by 3 inches and produces ten million maxwells of flux. the armature core is 12 inches in length and 3.5 inches in diameter. the total resistance of the winding is 2 ohms. b) determine the total generated voltage if the armature is running at 1000 rpm and its winding is simplex lap connected.
Electrical Machines Numerical Problems 1. A four-pole, lap wound DC machine is having 500 conductors on its armature and running at 1000 rpm. The flux per pole is 30 m Wb Calculate the voltage induced in the armature winding. What will be induced emf if the armature is rewound for wave winding? (Ans. 250 V, 500 V) 2. A 4-pole machine has an armature with 90 slots and 8 conductors per slot, the flux per pole is 0.05 Wb and runs at 1200 rpm. Determine induced emf if winding is (i) lap connected (ii) wave connected. (Ans. 720 V, 1440 V
Stray losses represent: O A. Resistive losses in the windings of the machine O B. Losses due to friction of the moving parts O C. Losses due to magnetization and demagnetization of the core O D. Windage losses O E. None of the other choices are correct
Q2. A 4-pole, wave-wound armature has 72 slots with two coil-sides per slot, each coil has four turns. If the flux per pole is 20 mWb and the armature rotates at 720 rpm, what is the induced emf across the armature? (Ans. 276.48 V) 0.05
The total conductor of the direct current generator shown in the figure is 1440. The length of the armature is 30cm, the magnetic flux of a pole is 0.8 Tesla and the armature rotates at a speed of 4 m / s. Find the value of the voltage generated by the armature according to the position in the figure.
A six-pole dc machine has an armature connected as a lap winding. The armature has 32 slots with six conductors per slot. The armature is rotated at 600 rpm, and the flux per pole is 30 mWb. Calculate the induced voltage. 1
A dc machine has 4-pole, wave wound armature with 46 slots and 16 conductors per slot. If induced voltage in the armature is 480 V at 1,200 rpm, determine the flux per pole
3.3. The current in a conductor on the armature of a DC motor is 300A. The flux under the poles is 850 micro-Weber. The area per pole is 700 mm². The length of the conductor on the armature is 640mm. Calculate the force exerted on the conductor.