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1) If speed of a synchronous generator decresed from 1800 RPM to 900 RPM the emf of one phase become a) one-fourth b) one-half c)one-fifth d)Twice 2) The voltage regulation of alternator depends on which factor: a) Both of these b) power factor c)load current d) non of these 3) For a synchronous machine three phase armature to have a 0.966 distribution factor the number of slots per pole per phase, and the number of slots per pole should be, respectively: a) 9,3 b)5,15 c) 1,3 d)2,6 4) A synchronous machine has its field winding on the rotor and polyphaser armature winding on the stator. When running under steady state conditions, its air gap field is a) Stationary with respect to stator b) Rotating at svnchronous speed Ns with resnect

1) If speed of a synchronous generator decresed from 1800 RPM to 900 RPM the emf of one phase become a) one-fourth b) one-half c)one-fifth d)Twice 2) The voltage regulation of alternator depends on which factor: a) Both of these b) power factor c)load current d) non of these 3) For a synchronous machine three phase armature to have a 0.966 distribution factor the number of slots per pole per phase, and the number of slots per pole should be, respectively: a) 9,3 b)5,15 c) 1,3 d)2,6 4) A synchronous machine has its field winding on the rotor and polyphaser armature winding on the stator. When running under steady state conditions, its air gap field is a) Stationary with respect to stator b) Rotating at svnchronous speed Ns with resnect

Introductory Circuit Analysis (13th Edition)
Introductory Circuit Analysis (13th Edition)
13th Edition
ISBN:9780133923605
Author:Robert L. Boylestad
Publisher:Robert L. Boylestad
Chapter1: Introduction
Section: Chapter Questions
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Choose the correct answer 1) If speed of a synchronous generator decresed from 1800 RPM to 900 RPM the emf of one phase become a) one-fourth b) one-half c)one-fifth d)Twice 2) The voltage regulation of alternator depends on which factor: a) Both of these b) power factor c)load current d) non of these 3) For a synchronous machine three phase armature to have a 0.966 distribution factor the number of slots per pole per phase, and the number of slots per pole should be, respectively: a) 9,3 b)5,15 c) 1,3 d)2,6 4) A synchronous machine has its field winding on the rotor and polyphaser armature winding on the stator. When running under steady state conditions, its air gap field is b) Rotating at synchronous speed Ns with respect C) Rotating at double the Ns with respect to rotor a) Stationary with respect to stator to stator d) Stationary with respect to rotor e) Rotating at ns in the direction of rotor rotation f) answer b,d,e g)answer c,d,e 5) An electric machine is considered as synchronous machine only if a) Stator flux, rotor speed, stator current frequency have invariant relationship during machine operation c) All of the above b) The rotor speed is equal to stator produced flux speed d) Stator current frequency is equal to rotating flux frequency 6) The losses in a synchronous machine a) Mechanical loss b) All of theses c) stray loss d) Iron loss e) Copper loss 7) A three-phase, 250 hp, 2300 V, 60 Hz, Y-connected non salient rotor synchronous motor has asynchronous reartance of 11 ohms per phase. When it draws 165.8 kW, the power angle is 15electrical degrees. Neglect ahmic losses, power factor is a) 0.8 lagging b) None of these c) 0.77 lagging d) 0.77 leading 8) For eliminating the 7th harmonic of the emf wave of an alternator the fractional pitch must be a) 7/6 b) 7/8 c)none of these d) 2/3 9) For which value of power factor the effect of armature reaction is minimum: a) leading 10) A 3 phase, 2-pole alternator has 24 stator slots carrying a 3 phase distributed winding. Each coll of the winding in short charded by one slot-pitch The winding factor (Kw) is b) 0.5 P.F lagging or leading c) lagging d)Unity a) 0.8565 b)0.9147 c)0.8565 c) None of these
Transcribed Image Text:Choose the correct answer 1) If speed of a synchronous generator decresed from 1800 RPM to 900 RPM the emf of one phase become a) one-fourth b) one-half c)one-fifth d)Twice 2) The voltage regulation of alternator depends on which factor: a) Both of these b) power factor c)load current d) non of these 3) For a synchronous machine three phase armature to have a 0.966 distribution factor the number of slots per pole per phase, and the number of slots per pole should be, respectively: a) 9,3 b)5,15 c) 1,3 d)2,6 4) A synchronous machine has its field winding on the rotor and polyphaser armature winding on the stator. When running under steady state conditions, its air gap field is b) Rotating at synchronous speed Ns with respect C) Rotating at double the Ns with respect to rotor a) Stationary with respect to stator to stator d) Stationary with respect to rotor e) Rotating at ns in the direction of rotor rotation f) answer b,d,e g)answer c,d,e 5) An electric machine is considered as synchronous machine only if a) Stator flux, rotor speed, stator current frequency have invariant relationship during machine operation c) All of the above b) The rotor speed is equal to stator produced flux speed d) Stator current frequency is equal to rotating flux frequency 6) The losses in a synchronous machine a) Mechanical loss b) All of theses c) stray loss d) Iron loss e) Copper loss 7) A three-phase, 250 hp, 2300 V, 60 Hz, Y-connected non salient rotor synchronous motor has asynchronous reartance of 11 ohms per phase. When it draws 165.8 kW, the power angle is 15electrical degrees. Neglect ahmic losses, power factor is a) 0.8 lagging b) None of these c) 0.77 lagging d) 0.77 leading 8) For eliminating the 7th harmonic of the emf wave of an alternator the fractional pitch must be a) 7/6 b) 7/8 c)none of these d) 2/3 9) For which value of power factor the effect of armature reaction is minimum: a) leading 10) A 3 phase, 2-pole alternator has 24 stator slots carrying a 3 phase distributed winding. Each coll of the winding in short charded by one slot-pitch The winding factor (Kw) is b) 0.5 P.F lagging or leading c) lagging d)Unity a) 0.8565 b)0.9147 c)0.8565 c) None of these
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