What is the use of fast recovery diode?
Last Answer : Fast recovery diode are used in high frequency rectification. Fast recovery diode also used for freewheeling. Fast recovery diode also used for DC to DC converter.
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98 views
1 answer
asked
Dec 9, 2017
by
anonymous
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State importance of colour scheme for pattern. Illustrate a common colour scheme.
Last Answer : Importance of Color coding used for pattern - Identify the core prints, loose pieces etc. - Identify quickly the main body of the pattern and different parts of the pattern to form the main body of ... for loose pieces Black strips on yellow base:- Stop offs Clear or No colour:- Parting surface
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47 views
1 answer
asked
Jan 2, 2021
by
anonymous
State the requirements of illumination scheme of shipyard.
Last Answer : Requirements of illumination scheme of shipyard: 1) The shipyard lighting always depends upon the surrounding conditions. e.g. wind pressure, rain fall, location of shipyard from the sea-share etc. ... solar grass lamps, LED-Solar energy lawn lamps, various focus lamps, metal halide lamps etc.
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178 views
1 answer
asked
May 3, 2020
by
anonymous
Explain the lighting scheme to be designed for each of the following: i) Special ward in hospitals ii) Dentist’s Cabin
Last Answer : i) Special ward in hospital: For the patients in the wards, lighting should create a cozy and pleasant atmosphere. Lighting in the wards should be planned in such a way that it meets the specific ... we use such as cements and bonding agents that we use to restore your teeth back to health.
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190 views
1 answer
asked
May 3, 2020
by
anonymous
State design considerations for illumination scheme of commercial complex.
Last Answer : Design considerations for illumination scheme of commercial complex: * Tasks to be performed in the space * Desired light levels based on the tasks performed in the space * Room size ... conditions * Cleanliness of the area during operation * Maintenance schedule * Availability of daylight
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93 views
1 answer
asked
May 3, 2020
by
anonymous
Advantages of Grid distribution scheme
Last Answer : Advantages of Grid distribution scheme 1. Supply to distribution transformer center is given through two different generating stations or major generating stations 2. It has highest reliability to ... highest reliability to maintain supply even when there was maintenance on any one feeder.
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78 views
1 answer
asked
Aug 25, 2019
by
anonymous
different types of distribution scheme.
Last Answer : According to scheme of connection: - a) Radial (Tree) distribution system b) Ring mains (Loop) distribution system c) Grid (interconnected) distribution system OR Types of ... distribution system b) Ring mains (Loop) distribution system c) Grid (interconnected) distribution system
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91 views
1 answer
asked
Aug 25, 2019
by
anonymous
In slip-energy recovery scheme of converter-fed 3-phase induction motor, super synchronous speeds are possible by (A) injecting voltage into the stator (B) injecting voltage into the rotor (C) extracting voltage from the stator (D) extracting voltage from the rotor.
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70 views
0 answers
asked
Jun 4, 2018
by
anonymous
Is the Trickster in you? Do you think the Trickster is bad?
Last Answer : answer:I used to do it all the time when playing with my kids. Until they began to beat me for real. It is nice that your group does that. He must never find out.
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1 answer
asked
Feb 28
by
anonymous
What makes time fly?
Last Answer : Reading Neil Stephenson novels, if you’re into that kind of thing.
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1 answer
asked
Feb 27
by
anonymous
In static Kramer drive, motor turns ratio is 0.6, the firing angle is 120o. The motor slip is (a) 0.633 (b) 0.533 (c) 0.833 (d) 0.733
Last Answer : In static Kramer drive, motor turns ratio is 0.6, the firing angle is 120o. The motor slip is 0.833
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226 views
1 answer
asked
May 13, 2018
by
anonymous
A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3
Last Answer : Answer: A
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6 views
1 answer
The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip ... D. If the motor is loaded to the point where 40% slip has resulted, it will stall.
Last Answer : Answer: D
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1 answer
A three-phase, squirrel cage, induction motor will run hot due to _____________. A. open stator coils B. high power factor C. dirty or corroded slip rings D. reversed commutating poles
Last Answer : Answer: A
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8 views
1 answer
The reversal of an AC, three-phase, induction motor is accomplished by ______________. A. changing all three motor leads B. reversing the position of the slip rings C. interchanging any two of the three motor leads D. interchanging any two brushes
Last Answer : Answer: C
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9 views
1 answer
A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to the rotor structure is (A) 1500 r.p.m. (B) 1425 r.p.m. (C) 25 r.p.m. (D) 75 r.p.m.
Last Answer : (D) 75 r.p.m.
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57 views
1 answer
To reverse the direction of rotation of a three-phase AC induction motor, do one of the following: w) reverse any two of the three-phase connections x) change the frequency of the applied AC power y) operate the motor below the stall torque at very high slip z) none of the above
Last Answer : ANSWER: W -- REVERSE ANY TWO OF THE THREE-PHASE CONNECTIONS
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30 views
1 answer
asked
Mar 6, 2021
by
anonymous
A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is: (1) Slip frequency (2) Supply frequency (3) Frequency corresponding to rotor speed (4) Zero
Last Answer : A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is: Slip frequency
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2.2k views
1 answer
asked
May 22, 2018
by
anonymous
A three phase slip ring induction motor with chopper controlled resistance has its torque proportional to (a) Rotor current (b) Stator resistance (c) Square of rotor current (d) Square root of rotor current
Last Answer : A three phase slip ring induction motor with chopper controlled resistance has its torque proportional to Square of rotor current
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410 views
1 answer
asked
May 13, 2018
by
anonymous
The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is
Last Answer : The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is 4 percent
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365 views
1 answer
asked
Apr 29, 2018
by
anonymous
The power input to the rotor of a 400V, 50 Hz 6 pole three phase induction motor is 20kW. The slip is 3%. The frequency of rotor currents is: (A) 1 Hz (B) 1.5 Hz (C) 2 Hz (D) 1 2 Hz
Last Answer : C
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647 views
1 answer
asked
Apr 14, 2018
by
anonymous
At slip equal to infinity, the torque of a three phase induction motor is :- a) zero b) very small c) high d) very high
Last Answer : At slip equal to infinity, the torque of a three phase induction motor is :- zero
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2.9k views
1 answer
asked
Apr 11, 2018
by
anonymous
Mark the correct option relating to SO Slip a) SO slip prepared in form Pa 3 by HO to each of its SO in every day enclosed in the account bag b) Amount with details, of cash (including stamps) sent ... HO. d) Particulars of documents and ser No and value of Postal order, sent to SO e) All the above
Last Answer : e) All the above
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2 views
1 answer
A 3 phase 50 Hz induction motor has full load speed of 970 rpm. Calculate no of poles and slip frequency.
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13 views
0 answers
asked
Apr 15
by
anonymous
A 400kW, 3-phase, 440V, 50Hz induction motor has a speed of 950 r.p.m. on fullload. The machine has 6 poles. The slip of the machine will be _______________. (A) 0.06 (B) 0.10 (C) 0.04 (D) 0.05
Last Answer : Ans: D N = Ns (1-S) 950 = 120 x 50 (1-S)/6 S = 0.05
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99 views
1 answer
The rotor power output of a 3-phase induction motor is 15 KW and corresponding slip is 4%. The rotor copper loss will be (A) 600 W. (B) 625 W (C) 650 W (D) 700 W
Last Answer : Ans: B Rotor copper losses = rotor input- rotor output and output = (1-s) input ∴ Input = output/(1-s) = 15000 /1-0.04 = 15625 ∴ loss = 15625 -1500 = 625 watt
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306 views
1 answer
A 3-phase, 400 votts, 50 Hz, 100 KW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm
Last Answer : Ans: B N = NS (1-S) and NS =120 f / p =120 x 50 /4 = 1500 rpm ∴N= 1500 (1-0.02) =1470 rpm
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75 views
1 answer
The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm
Last Answer : (D) 1710 rpm
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166 views
1 answer
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The rotor frequency for a 3 phase 1000 RPM 6 pole induction motor with a slip of 0.04 is________Hz (A) 8 (B) 4 (C) 6 (D) 2
Last Answer : Ans: D Given: N=1000 rpm ; P= 6; s= 0.04; and f = NP/ 120 = 10006/120 = 50 Hz Rotor frequency fr=sf = 0.0450 = 2.0 Hz
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104 views
1 answer
The rotor frequency for a 3-phase 6-pole, 1000 r.p.m. induction motor with a slip of 0.04 is (a) 2 Hz (b) 4 Hz (c) 6 Hz (d) 8 Hz
Last Answer : 2hz is rotor frequency
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1.2k views
1 answer
asked
May 25, 2018
by
anonymous
A 3-phase induction motor is running at slip ‘s’. If its two supply leads are interchanged, then the operating slip at that instant will be:
Last Answer : A 3-phase induction motor is running at slip ‘s’. If its two supply leads are interchanged, then the operating slip at that instant will be: (2-s)
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526 views
1 answer
asked
May 22, 2018
by
anonymous
If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is:
Last Answer : If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is: zero
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874 views
1 answer
asked
May 22, 2018
by
anonymous
What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these
Last Answer : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these
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127 views
1 answer
asked
Apr 29, 2018
by
anonymous
The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down
Last Answer : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque
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3.1k views
1 answer
asked
Apr 28, 2018
by
anonymous
In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is (A) 0.2 Ω (B) 0.3 Ω (C) 0.4 Ω (D) 0.5 Ω
Last Answer : In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is 0.3 Ω
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169 views
1 answer
asked
Apr 28, 2018
by
anonymous
A 3 phase, 400 volts, 50 Hz, 100 kW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of: (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm
Last Answer : 1470rpm
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784 views
2 answers
asked
Apr 11, 2018
by
anonymous
The rotor power output of a 3 -phase induction motor is 15 kW and the corresponding slip is 4%. The rotor copper losses will be: (A) 600 W (B) 625 W (C) 650 W (D) 700 W
Last Answer : The rotor power output of a 3 -phase induction motor is 15 kW and the corresponding slip is 4%. The rotor copper losses will be: 625 W
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1.1k views
1 answer
asked
Apr 11, 2018
by
anonymous
If the supply frequency of a 3-phase induction motor is ‘f’, then frequency of rotor emf at motor slip ‘s’ will be (a) sf (b) (1 – s)f (c) f/s (d) None of these
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151 views
0 answers
asked
Apr 10, 2018
by
anonymous
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A 3-phase, 50 Hz, 500 V induction motor develops 20 hp at slip of 5%. Mechanical losses are 1 hp, and stator loss is 1 kW. The efficiency will be (a) 95.3% (b) 90.5% (c) 91.3% (d) 85.3%
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212 views
0 answers
asked
Apr 10, 2018
by
anonymous
At a slip of 4%, maximum possible speed of a 3-phase squirrel cage induction motor is (a) 2880 rpm (b) 3000 rpm (c) 1500 rpm (d) 1440 rpm
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975 views
0 answers
asked
Apr 10, 2018
by
anonymous
The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α
Last Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ
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153 views
1 answer
asked
Apr 28, 2018
by
anonymous
The direction of rotation of an inverter fed 3-phase ac motor is reversed by (A) a mechanical reversing switch (B) reversing the input dc link voltage (C) operating the inverter as a rectifier (D) changing the sequence of switching
Last Answer : The direction of rotation of an inverter fed 3-phase ac motor is reversed by changing the sequence of switching
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153 views
1 answer
asked
Apr 28, 2018
by
anonymous
In a three phase controlled bridge rectifier with an increase of overlap angles the output dc voltage
Last Answer : In a three phase controlled bridge rectifier with an increase of overlap angles the output dc voltage decreases
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1.0k views
1 answer
asked
May 23, 2018
by
anonymous
A four-pole 60-hertz induction motor has a synchronous speed of 1800 RPM and a slip of 4 percent at full load. What will be its full load speed? A. 1728.0 RPM B. 1730.7 RPM C. 1800.0 RPM D. 1872.0 RPM
Last Answer : Answer: A
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6 views
1 answer
What is the rotor speed of a four pole, 60 cycle, induction motor operating at full load with 3% slip? A. 270 RPM B. 540 RPM C. 873 RPM D. 1746 RPM
Last Answer : Answer: D
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8 views
1 answer
If an induction motor were to be operated at 90% rated voltage, _____________. A. there would be an increase in starting torque B. starting current would increase slightly C. synchronous speed would decrease slightly D. the slip would increase
Last Answer : Answer: D
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1 view
1 answer
The synchronous speed of an induction motor is the ________. A. speed at which the rotor turns B. speed of the rotating field C. frequency of the rotor current D. slip in per cent of rotor RPM
Last Answer : Answer: B
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7 views
1 answer
A degree of control over the speed of a slip ring induction motor can be obtained by _____________. A. adjusting governor linkage B. changing the number of phases to the motor C. inserting resistance into the stator circuit D. inserting resistance into the rotor circuit
Last Answer : Answer: D
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4 views
1 answer
In an induction motor, rotor currents are circulated in the rotor by _____________. A. slip rings and brushes B. an armature and brushes C. inductive reaction of the rotating stator field D. external variable resistors
Last Answer : Answer: C
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3 views
1 answer
Which of the following physical characteristics does a wound-rotor induction motor possess that a squirrel cage motor does not? A. Slip rings B. End rings C. A centrifugal switch D. End plates
Last Answer : Answer: A
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7 views
1 answer
