Description : Define pitch factor or coil span factor.
Last Answer : The pitch factor is defined as the ratio of vector sum of emf induced in a coil to arithmetic sum of emf induced in the coil OR It is the ratio of resultant emf induced when coil is short pitch to the resultant emf induced when the coil is full pitched.
Description : When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of (a) short pitch (b) full pitch (c) either of the above (d) none of the above
Last Answer : (b) full pitch
Description : A 36 slot, 4 -pole, dc machine has a simplex lap winding with two conductors per slot. The back pitch and front pitch adopted could be respectively
Last Answer : A 36 slot, 4 -pole, dc machine has a simplex lap winding with two conductors per slot. The back pitch and front pitch adopted could be respectively 19,17
Description : Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is (A) 48 (B) 24 (C) 192 (D) 96
Last Answer : Number of commutator bars for a 4-pole, 2-layer, DC lap winding with 24 slots and one conductor per layer is 24
Description : In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50
Last Answer : In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50
Description : In D.C. machines the number of slots per pole usually lies (a) between 2 to 4 (b) between 6 to 8 (c) between 9 to 16 (d) between 20 to 30
Last Answer : (c) between 9 to 16
Description : One factor that determines the frequency of an alternator is the ____________. A. number of turns of wire in the armature coil B. number of magnetic poles C. strength of the magnets used D. output voltage
Last Answer : Answer: B
Description : Three factors responsible for the change in voltage as load is applied to an AC generator are: 1) the drop in resistance in the armature circuit, 2) the change in flux, and 3) the ____________. A. armature winding speed B. inductance load drop C. coil pitch factor D. armature reactance voltage drop
Last Answer : Answer: D
Description : If the rise is 8 feet and the span is 30 feet what is the pitch in simples form?
Last Answer : roof pitch 14.9 degrees, or roof pitch 26.6%
Description : An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: A) 1000 rpm B) 920 rpm C) 950 rpm D) 970 rpm
Last Answer : An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: 970 rpm
Description : A 8 pole alternator rotates at 750 r.p.m. Its frequency is
Last Answer : A 8 pole alternator rotates at 750 r.p.m. Its frequency is 50 Hz
Description : Advantages of Short Pitch Coils for an Alternator
Last Answer : Advantages of Short Pitch Coils for an Alternator: (1) It gives better sinusoidal waveform by reducing the harmonic components. (2) It saves copper as length required for the connections is ... are illuminated, hysteresis & eddy current losses will be reduced and this increases the efficiency.
Description : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is (A) 2/3 (B) 5/6 (C) 7/8 (D) 6/7
Last Answer : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is 6/7
Description : An alternator is delivering rated current at rated voltage and 0.8 power-factor lagging. For delivering rated current at rated voltage and 0.8 poWer—factor leading, the required excitation will be: (A) less (B) more (C) more or less (D) the same
Last Answer : An alternator is delivering rated current at rated voltage and 0.8 power -factor lagging. For delivering rated current at rated voltage and 0.8 power -factor leading, the required excitation will be: more
Description : What are the prime movers used for a) Salient pole alternator, b) Non- salient pole alternator.
Last Answer : The prime movers used for salient pole alternators are water wheels likeKaplan turbine, Francis turbine, Pelton wheel etc., and diesel or petrol engines. The prime movers used for non-salient pole alternators are steam turbines and gas turbines.
Description : The number of electrical degrees ‘passed through’ in one revolution of a 6-pole synchronous alternator is: A) 360 degree B) 720 degree C) 1080 degree D) 2160 degree
Last Answer : 1080
Description : A 60 Hz, 2 pole alternator should run at • a. 3000 r.p.m. c. 1500 r.p.m. • b. 3600 r.p.m. d. 1800 r.p.m.
Last Answer : A 60 Hz, 2 pole alternator should run at 3600 r.p.m.
Description : Slip test is performed to determine : (A) Slip in an induction motor (B) Xd and Xq in a salient pole alternator (C) Synchronous impedance in an alternator (D) Positive and negative sequence impedances of an alternator
Last Answer : Slip test is performed to determine : Xd and Xq in a salient pole alternator
Description : The frequency of an alternator at a given RPM is determined by the _____________. A. number of turns of wire in the armature coil B. number of magnetic poles C. strength of the magnets used D. output voltage
Description : The purpose of a main switchboard circuit breaker's reverse-power trip is to _____________. A. prevent main circuit overload B. protect the circuit breaker blowout coil C. prevent alternator motorization D. prevent low voltage tripout
Last Answer : Answer: C
Description : The frequency output of an operating alternator is controlled by the _____________. A. relative speed of the rotor poles B. number of turns of wire in the armature coil C. strength of the magnets used D. output voltage
Last Answer : Answer: A
Description : Define Pole Pitch?
Last Answer : The distance between the centers of two adjacent poles is called pole pitch. One pole pitch is equals to 180 electrical degrees. It is also defined as the number of slots per pole.
Description : Define pole pitch.
Last Answer : It is centre to centre distance between two adjacent poles. Two poles are responsible for 360 degree electrical of induced emf so one pole is responsible for 180 degree electrical of induced emf. Hence 180 degree electrical is called 1 pole pitch.
Description : A pole pitch in electrical machine is: (1) Equal to 180° electrical (2) Equal to 180° mechanical (3) Less than 180° electrical (4) Greater Than 180° electrical
Last Answer : A pole pitch in electrical machine is: Equal to 180° electrical
Last Answer : In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be 8.
Description : If uncompressed length of spring is 40mm and number of coils 10mm, then pitch of coil is? a) 4 b) 40/9 c) 40/11 d) None of the mentioned
Last Answer : b) 40/9
Description : Pitch of coil is defined as axial distance in compressed state of the coil. a) Yes b) It is measured in uncompressed state c) It is same in uncompressed or compressed state d) None of the listed
Last Answer : b) It is measured in uncompressed state
Description : Pick up the correct statement from the following: (A) A wire wound in spiral form, is called a helical spring (B) The pitch of a close coil spring, is very small (C) The angle made by the coil with horizontal, is called the angle of helix (D) All the above
Last Answer : (D) All the above
Description : The distance between the starts of two consecutive coils measured in terms of coil sides is called (a) front pitch (b) winding pitch (c) commutator pitch (d) back pitch
Last Answer : (b) winding pitch
Description : The designation M 36 × 2 means (A) Metric fine threads of 36 mm outside diameter and 2 mm pitch (B) Metric coarse threads of 36 mm outside diameter and 2 mm pitch (C) Metric threads of 36 mm pitch diameter and 2 mm pitch (D) Metric threads of 36 mm core diameter and 2 mm pitch
Last Answer : (A) Metric fine threads of 36 mm outside diameter and 2 mm pitch
Description : A alternator is delivering power to a balanced load at unit power factor. The phase angle between the line voltage and the line current is? (A) 90° (B) 60° (C) 30° (D) 0°
Last Answer : A alternator is delivering power to a balanced load at unit power factor. The phase angle between the line voltage and the line current is 30°
Description : Define Coil Span?
Last Answer : The distance between the two coil sides of a coil is called as coil span. It may be expressed in electrical degrees or in number of slots.
Description : A three-phase alternator is operating at 450 volts, 250 amps at 0.6 power factor. If the power factor increases to 0.8, the kw load potential will increase by _____________. A. 38.525 kw B. 116.91 kw C. 155.88 kw D. 194.85 kw
Description : A three-phase alternator operates at 450 volts with a power factor of 0.8. If the ammeter indicates 250 amperes, what should be the KW meter reading? A. 90.00 KW B. 127.27 KW C. 155.70 KW D. 194.85 KW
Description : A three-phase alternator is developing 300 amps, with a 0.8 power factor, at 450 volts. The true indicated power on the kilowatt meter, located on the main switchboard, will be ____________. A. 133 kw B. 155 kw C. 187 kw D. 212 kw
Description : A three-phase alternator is operating at 450 volts with the switchboard ammeter indicating 300 amps. The kw meter currently indicates 163.6 KW, with a power factor of 0.7. If the power factor increases to 0.8, the KW meter would then read ____________. A. 181.4 KW B. 186.8 KW C. 194.2 KW D. 201.4 KW
Description : A three-phase alternator is operating at 450 volts with the switchboard ammeter indicating 300 amps. The kw meter currently indicates 163.6 KW, with a power factor of 0.7. If the power factor increases to 0.8, the KW meter reading would increase by ___ A. 17.8 KW B. 23.2 KW C. 30.6 KW D. 37.8 KW
Description : At dead short circuit at terminals of Alternator then the current I is a) ZPF Lag b) ZPF lead c) Unity power factor d) 0.8 Power factor lag
Last Answer : Ans: ZPF Lag
Description : An alternator is delivering rated current at rated voltage and 0.8 power-factor lagging case. If it is required to deliver rated current at rated voltage and 0.8 power-factor leading, the required excitation will be (A) less. (B) more. (C) more or less. (D) the same.
Last Answer : Ans: B Over excitation gives leading power factor and under excitation gives lagging p.f .
Description : The pole pieces of the magnet used in a pivoted coil galvanometer are
Last Answer : The pole pieces of the magnet used in a pivoted coil galvanometer are A. plane surfaces of a ... magnet D. cylindrical sufaces of a horse-shoe magnet
Description : An open shunt field in a direct current machine may be located by connecting the field circuit to an external power source, equal to the rated field voltage or less, and tested with a voltmeter from ... C. any suitable ground to any available line lead D. any field pole to each field coil lead
Description : If a DC motor runs faster than designed, with all other conditions being normal, the possible cause could be a/an ______________. A. shorted shunt field coil B. open armature coil C. reversed commutating pole D. overload
Description : A megohmmeter can be used to test for _____________. A. an open field coil B. a shorted field pole C. undercut mica D. reversed polarity
Description : Reversing the current flow through a coil will ___________. A. reduce the amount of flux produced B. have no effect on the eddy currents produced C. reduce the power consumed D. reverse its two-pole field
Description : A three-phase, induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the machine from being damaged? A. Overspeed trip B. Thermal overload relay C. Three-pole safety switch D. Magnetic blowout coil
Description : The pole faces of U-shaped magnet in a moving coil galvanometer are made concave to a) decrease the strength of magnetic field b) create a non-uniform magnetic field c) make the magnetic field radial d) All of these
Last Answer : c) make the magnetic field radial
Description : The introduction of interpoles in between the main pole improves the performance of d.c. machines, because (A) The interpole produces additional flux to augment the developed torque. (B) The flux waveform is ... armature is removed. (D) A counter e.m.f. is induced in the coil undergoing commutation.
Last Answer : Ans: D Counter e.m.f is produced, it neutralizes the reactive emf.
Last Answer : In a shaded pole motor, the shading coil usually consist of a single turn of heavy copper wire which is short-circuited and carries only induced current.
Last Answer : The purpose of skewing of rotor slots in induction motor is to reduce the locking tendency of rotor.
Description : In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine ... in an oven at a maximum of 95°C for not over 8 hours D. all of the above