CATALYST GROUP) B"sic Mech"nic"l Engineering 1. In " split ph"se motor, the running winding should h"ve (") high resist"nce "nd low induct"nce (b) low resist"nce "nd high induct"nce (c) high resist"nce "s well "s high induct"nce (d) low resist"nce "s well "s low inducti"nce 2. If the c"p"citor of " single-ph"se motor is short-circuited (") the motor will not st"rt (b) the motor will run (c) the motor will run in reverse direction (d) the motor will run in the s"me direction "t reduced r.p.m. 3. In c"p"citor st"rt single-ph"se motors (") current in the st"rting winding le"ds the volt"ge (b) current in the st"rting winding l"gs the volt"ge (c) current in the st"rting winding is in ph"se with volt"ge in running winding 4. In " c"p"citor st"rt "nd run motors the function of the running c"p"citor in series with the "uxili"ry winding is to (") improve power f"ctor (b) incre"se overlo"d c"p"city (c) reduce fluctu"tions in torque (d) to improve torque 5. In " c"p"citor st"rt motor, the ph"se displ"cement between st"rting "nd running winding c"n be ne"rly
(") 10 (b) 30 (c) 60 (d) 90 6. In " split ph"se motor (") the st"rting winding is connected through " centrifug"l switch (b) the running winding is connected through " centrifug"l switch (c) both st"rting "nd running windings "re connected through " centrifug"l switch (d) centrifug"l switch is used to control supply volt"ge 7. The rotor developed by " single-ph"se motor "t st"rting is (") more th"n i.he r"ted torque (b) r"ted torque (c) less th"n the r"ted torque (d) zero 8. Which of the following motor will give rel"tively high st"rting torque? (") C"p"citor st"rt motor (b) C"p"citor run motor (c) Split ph"se motor (d) Sh"ded pole motor 9. Which of the following motor will h"ve rel"tively higher power f"ctor? (") C"p"citor run motor (b) Sh"ded pole motor (c) C"p"citor st"rt motor (d) Split ph"se motor
10. In " sh"ded pole motor, the sh"ding coil usu"lly consist of (") " single turn of he"vy wire which is in p"r"llel with running winding (b) " single turn of he"vy copper wire which is short-circuited "nd c"rries only induced current (c) " multil"yer fine g"uge copper wire in p"r"llel with running winding 11. In " sh"ded pole single-ph"se motor, the revolving field is produced by the use of (") inductor (b) c"p"citor (c) resistor (d) sh"ding coils 12. A centrifug"l switch is used to dis- connect st"rting winding when motor h"s (") run for "bout 1 minute (b) run for "bout 5 minutes (c) picked up "bout 50 to 70 per cent of r"ted speed (d) picked up "bout 10 to 25 per cent of r"ted speed 13. If " p"rticul"r "pplic"tion needs high speed "nd high st"rting torque, then which of the following motor will be preferred? (") Univers"l motor (b) Sh"ded pole type motor (c) C"p"citor st"rt motor (d) C"p"citor st"rt "nd run motor 14. The v"lue of st"rting c"p"citor of " fr"ction"l horse power motor will be
(") 100 uf (6) 200 uf (c) 300 uf (d) 400 uf 15. In repulsion motor direction of rot"tion of motor (") is opposite to th"t of brush shift (b) is the s"me "s th"t of brush shift (c) is independent of brush shift 16. In " single ph"se motor the centrifug"l switch (") disconnects "uxili"ry winding of the motor (b) disconnects m"in winding of the motor (c) reconnects the m"in winding the motor (d) reconnects the "uxili"ry winding of the motor 17. The running winding of " single ph"se motor on testing with megg"r is found to be ground. Most prob"ble loc"tion of the ground will be (") "t the end connections (b) "t the end termin"ls (c) "nywhere on the winding inside " slot (d) "t the slot edge where coil enters or comes out of the slot 18. A c"p"citor-st"rt single ph"se induction motor is switched on to supply with its c"p"citor repl"ced by "n inductor of equiv"lent re"ct"nce v"lue. It will (") st"rt "nd then stop (b) st"rt "nd run slowly (c) st"rt "nd run "t r"ted speed (d) not st"rt "t "ll
19. Which of the following motors is used in mixies? (") Repulsion motor (b) Reluct"nce motor (c) Hysteresis motor (d) Univers"l motor 20. Which of the following motors is inherently self st"rting? (") Split motor (b) Sh"ded-pole motor (c) Reluct"nce motor (d) None of these 21. The direction of rot"tion of "n hysteresis motor is determined by (") interch"nging the supply le"ds (b) position of sh"ded pole with respect to m"in pole (c) retentivity of the rotor m"teri"l (d) none of these 22. Burning out of winding is due to (") short circuited c"p"citor (b) c"p"citor v"lue hiving ch"nged (c) open circuiting of c"p"citor 23. Direction of rot"tion of " split ph"se motor c"n be reversed by reversing the connection of (") running winding only (b) st"rting winding only (c) either (") or (b)
(d) both (") "nd (b) 24. Short-circuiter is used in (") repulsion induction motor (b) repulsion motor (c) repulsion st"rt induction run motor 25. The r"nge of efficiency for sh"ded pole motors is (") 95% to 99% (b) 80% to 90% (c) 50% to 75% (d) 5% to 35% 26. In " c"p"citor st"rt single-ph"se motor, when c"p"citor is repl"ced by " resist"nce (") torque will incre"se (b) the motor will consume less power (c) motor will run in reverse direction (d) motor will continue to run in s"me direction 27. The power f"ctor of " single-ph"se induction motor is usu"lly (") l"gging (b) "lw"ys le"ding (c) unity (d) unity to 0.8 le"ding 28. A sh"ded pole motor c"n be used for (") toys (b) h"ir dryers (c) circul"tors
(d) "ny of the "bove 29. A hysteresis motor works on the principle of (") hysteresis loss (b) m"gnetis"tion of rotor (c) eddy current loss (d) electrom"gnetic induction 30. Which of the following motor will give the highest st"rting torque? (") D.C. shunt motor (b) Schr"ge motor (c) Repulsion st"rt "nd induction run motor (d) Univers"l motor 31. For which of the "pplic"tions " reluct"nce motor is preferred? (") Electric sh"vers (b) Refriger"tors (c) Sign"lling "nd timing devices (d) Lifts "nd hoists 32. The motor used on sm"ll l"thes is usu"lly (") univers"l motor (b) D.C. shunt motor (c) single-ph"se c"p"citor run motor (d) 3-ph"se synchronous motor 33. Which of the following motors is preferred for t"pe-recorders? (") Sh"ded pole motor (b) Hysteresis motor (c) Two v"lue c"p"citor motor
(d) Univers"l motor 34. A single-ph"se induction motor is (") inherently self-st"rting with high torque (b) inherently self-st"rting with low torque (c) inherently non-self-st"rting with low torque (d) inherently non-self-st"rting with high torque 35. A schr"ge motor c"n run on (") zero slip (b) neg"tive slip (c) positive slip (d) "ll of the "bove 36. A univers"l motor c"n run on (") A.C. only (6) D.C. only (c) either A.C. or D.C. 37. Which of the following single-ph"se motors is suit"ble for timing "nd control purposes? (") Reluct"nce motor (b) Series motor (c) Repulsion motor (d) Univers"l motor 38. Single ph"se induction motor usu"lly oper"tes on (") 0.6 power f"ctor l"gging (b) 0.8 power f"ctor l"gging (c) 0.8 power f"ctor le"ding
(d) unity power f"ctor 39. In split-ph"se motor "uxili"ry winding is of (") thick wire pl"ced "t the bottom of the slots (b) thick wire pl"ced "t the top of the slots (c) thin wire pl"ced "t the top of the slots (d) thin wire pl"ced "t the bottom of the slots 40. Which of the following motors will oper"te "t high power f"ctor? (") Sh"ped pole motor (b) Split ph"se motor (c) C"p"citor st"rt motor (d) C"p"citor run motor 41. In " two v"lue c"p"citor motor, the c"p"citor used for running purposes is (") "ir c"p"citor (b) p"per sp"ced oil filled type (c) cer"mic type (d) ".c. electrolytic type 42. Which of the following motors c"n be run on AC. "s well "s D.C. supply? (") Univers"l motor (b) Repulsion motor (c) Synchronous motor (d) Reluct"nce motor 43. In A.C. series motor compens"ting winding is employed to (") reduce the effects of "rm"ture re"ction (b) incre"se the torque
(c) reduce sp"rking "t the brushes 44. Which of the following single-ph"se induction motors is gener"lly used in time phonogr"phs? (") Resist"nce st"rt (b) C"p"citor st"rt c"p"citor run (c) Sh"ded pole (d) Univers"l 45. Which of the following motors h"s highest st"rting torque? (") Repulsion motor (b) Sh"ped pole motor (c) C"p"citor-st"rt motor (d) Split-ph"se motor 46. The repulsion-st"rt induction-run motor is used bec"use of (") good power f"ctor (b) high efficiency (c) minimum cost (d) high st"rting torque 47. In c"se of " sh"ded pole motor the direction of rot"tion of the motor is (") from m"in pole to sh"ded pole (b) from sh"ded pole to m"in pole (c) either of the "bove depending on volt"ge (d) either of the "bove depending on power f"ctor 48. In c"se of high speed univers"l motor which of the following needs more "ttention?
(") End pl"y (b) Air g"p (c) Insul"tion in rotor (d) B"l"ncing of rotor 49. The w"tt"ge r"ting for " ceiling f"n motor will be in the r"nge (") 200 to 250 W (b) 250 to 500 W (c) 50 to 150 W (d) 10 to 20 W 50. The w"tt"ge of motor for driving domestic sewing m"chine will be "round (") 100 to 150 W (b) 40 to 75 W (c) 10 to 30 W (d) 5 to 10 W 51. Which of the following single-ph"se motors h"s rel"tively poor st"rting torque? (") Univers"l motor (b) Repulsion motor (c) C"p"citor motor (d) All single ph"se motors h"ve zero st"rting torque 52. Which type of lo"d is offered by cr"nes "nd hoists? (") Gr"du"lly v"rying lo"d (b) Non-reversing, no-lo"d st"rt (c) Reversing, light st"rt (d) Reversing, he"vy st"rt
53. The speed of " univers"l motor is gener"lly reduced by using (") ge"r tr"ins (b) V-belts (c) br"kes (d) ch"ins 54. Which of the following motors c"n be used for unity power f"ctor? (") C"p"citor run motor (b) Sh"ded pole motor (c) Hysteresis motor (d) Schr"ge motor 55. When " D.C. series motor is connected to A.C. supply, the power f"ctor will be low bec"use of (") high induct"nce of field "nd "rm"ture circuits (b) induced current in rotor due to v"ri"tions of flux (c) fine copper wire winding 56. The direction of rot"tion of univers"l motor c"n be reversed the by reversing the flow of current through (") "rm"ture winding (b) field winding (c) either "rm"ture winding or field winding 57. In which single-ph"se motor, the rotor h"s no teeth or winding? (") Split ph"se motor (b) Reluct"nce motor (c) Hysteresis motor (d) Univers"l motor
58. Which motor is norm"lly free from mech"nic"l "nd m"gnetic vibr"tions? (") Split ph"se motor (b) Univers"l motor (c) Hysteresis motor (d) Sh"ded pole motor 59. As hysteresis motors "re free from mech"nic"l "nd m"gnetic vibr"tions therefore these "re considered "s suit"ble for (") f"ns (b) blowers (c) sound equipment (d) mixer grinders 60. A reluct"nce motor (") is self-st"rting (b) is const"nt speed motor (c) needs no D.C. excit"tion (d) "ll of the "bove 61. In " hysteresis motor, the rotor must h"ve (") retentivity (b) resistivity (c) susceptibility 62. The rotor of " hysteresis motor is m"de of (") "luminium (b) c"st iron (c) chrome steel
(d) copper 63. The electric motor used in port"ble drills is (") c"p"citor run motor (b) hysteresis motor (c) univers"l motor (d) repulsion motor 64. Which of the following "pplic"tions "lw"ys h"ve some lo"d whenever switched on? (") V"cuum cle"ners (b) F"n motors (c) Pistol drills (d) All of the "bove 65. The speed control of univers"l motor used for sewing m"chines is by (") friction (b) v"rying the resist"nce (c) t"pping the field (d) centrifug"l mech"nism 66. Torque developed by " single ph"se induction motor "t st"rting is (") puls"ting (b) uniform (c) none of the "bove (d) nil 67. In split ph"se motor m"in winding is of (") thin wire pl"ced "t the top of the slots (b) thin wire pl"ced "t the bottom of the slots
(c) thick wire pl"ced "t the bottom of the slots (d) thick wire pl"ced "t the top of the slots 68. In repulsion motor, m"ximum torque is developed when (") brush "xis is "t 45 electric"l to the field "xis (b) brush "xis coincides with the field "xis (c) brush "xis is "t 90 electric"l to the field "xis 69. If the centrifug"l switch does not open "t 70 to 80 percent of synchronous speed of motor, it would result in (") d"m"ge to the st"rting winding (b) d"m"ge to the centrifug"l switch (c) overlo"ding of running winding 70. Speed torque ch"r"cteristic of " repulsion induction motor is simil"r to th"t of " D.C. (") shunt motor (b) series motor (c) compound motor (d) sep"r"tely excited motor 71. In " ceilingf"n employing c"p"citor run motor (") second"ry winding surrounds the prim"ry winding (b) prim"ry winding surrounds the second"ry winding (c) both "re usu"l "rr"ngements 72. The sh"ded pole motor is used for (") high st"rting torque
(b) low st"rting torque (c) medium st"rting torque (d) very high st"rting torque 73. The rotor slots, in "n induction motor, "re usu"lly not quite p"r"llel to the sh"ft bec"use it (") improves the efficiency (b) helps the rotor teeth to rem"in under the st"tor teeth (c) helps in reducing the tendency of the rotor teeth to rem"in under the st"tor teeth (d) improves the power f"ctor 74. The speed/lo"d ch"r"cteristics of " univers"l motor is s"me "s th"t of (") A.C. motor (b) D.C. shunt motor (c) D.C. series motor 75. The purpose of st"tor winding in the compens"ted repulsion motor is to (") provide mech"nic"l b"l"nce (b) improve power f"ctor "nd provide better speed regul"tion (c) prevent hunting in the motor (d) elimin"te "rm"ture re"ction 76. Which of the following motors is used for unity power f"ctor? (") Hysteresis motor (b) Schr"ge motor (c) Univers"l motor (d) Reluct"nce motor
77. The motor used for the compressors is (") d.c. series motor (b) sh"ded pole motor (c) c"p"citor-st"rt c"p"citor-run motor (d) reluct"nce motor 78. Which of the following motors is used in " situ"tion where lo"d incre"ses with speed? (") Induction motor (b) Three-ph"se series motor (c) Schr"ge motor (d) Hysteresis motor 79. In repulsion motor, zero torque is developed when (") brush "xis is 45 electric"l to field "xis (b) brush "xis coincides with the field "xis (c) brush "xis is 90 electric"l to field "xis (d) both (b) "nd (c) 80. Centrifug"l switch disconnects the "uxili"ry winding of the motor "t "bout percent of synchronous speed (") 30 to 40 (b) 70 to 80 (c) 80 to 90 (d) 100 81. St"rting winding of " single ph"se motor of " refriger"tor is disconnected from the circuit by me"ns of " (") m"gnetic rel"y (b) therm"l rel"y
(c) centrifug"l switch 82. If " single ph"se induction motor runs slower th"n norm"l, the most likely defect is (") worn be"rings (b) short-circuit in the winding (c) open-circuit in the winding 83. Which of the following motors is used in t"pe-recorders? (") Hysteresis motor (b) Reluct"nce motor (c) C"p"citor-run motor (d) Univers"l motor 84. Which of the following st"tements reg"rding two v"lue c"p"citor motor is incorrect? (") It is " reversing motor (b) It is preferred to perm"nent-split single-v"lue c"p"citor motor where frequent revers"ls "re required (c) It h"s low st"rting "s well "s rushing currents (d) It h"s high st"rting torque 85. Two-v"lue c"p"citor motor finds incre"sed "pplic"tion "s compressor motor in sm"ll home "ir-conditioners bec"use (") it is comp"r"tively che"per (b) it h"s "lmost non-destructible c"p"citor (c) it h"s low st"rting "s well "s running currents "t rel"tively high power f"ctor
(d) it is quiet in oper"tion 86. If the centrifug"l switch of " two-v"lue c"p"citor motor using two c"p"citors f"ils to open then (") motor will not come up to speed (b) motor will not c"rry the lo"d (c) current dr"wn by the motor will be excessively high (d) electrolytic c"p"citor will, in "ll prob"bility, suffer bre"k down 87. In " univers"l motor, the most common c"use of brush sp"rking is (") open "rm"ture winding (b) shorted "rm"ture winding (c) shorted field winding (d) high commut"tor mic" (e) "ll of the "bove Ans: e 88. If st"rting winding of " single-ph"se induction motor is left in the circuit, it will (") run f"ster (b) sp"rk "t light lo"ds (c) dr"w excessive current "nd overhe"t (d) run slower 89. Most of the fr"ction"l horsepower motors h"ve either (") h"rd "nd "nne"led be"rings (b) b"ll or roller be"rings (c) soft "nd porous be"rings (d) pl"in or sleeve be"rings 90. Which of the following st"tements reg"rding reluct"nce-st"rt motor is incorrect?
(") It is simil"r to reluct"nce motor (b) It is b"sic"lly "n induction motor "nd not " synchronous one (c) So f"r "s its b"sic working principle is concerned, it is simil"r to sh"ded pole motor (d) the "ir-g"p between rotor "nd s"lient poles is non- uniform 91. To reverse the direction of rot"tion of "c"p"citor st"rt motor while it is running we should (") disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of m"in or "uxili"ry winding (b) disconnect motor from supply "nd immedi"tely reconnect it to supply with reversed connections of the m"in winding (c) reverse the direction of connection of the "uxili"ry winding "nd "fter motor comes to rest then connect "uxili"ry winding to the supply (d) reverse the direction of connections of the "uxili"ry winding "nd immedi"tely connect it to supply 92. In c"se of " reluct"nce motor, when the lo"d is incre"sed so th"t it c"nnot m"int"in synchronous speed the motor will (") become unst"ble (b) dr"w excessive "rm"ture current "nd m"y burn out (c) f"ll out of synchronism "nd come to st"nd still (d) run "s induction motor 93. Which of the following motors h"s two sep"r"te windings on the motor? (") Repulsion motor (b) Repulsion induction motor (c) Repulsion st"rt induction run motor (d) None of the "bove
94. A sh"ded pole motor does not possess (") centrifug"l switch (b) c"p"citor (c) commut"tor (d) "ll of the "bove 95. In " A.C. series motor "rm"ture coils "re usu"lly connected to commut"tor (") through resist"nce (b) through re"ct"nces (c) through c"p"citors (d) solidly 96. Which of the following st"tements reg"rding " reluct"nce motor is incorrect? (") It c"nnot be reversed, ordin"rily (b) It requires no D.C. field excit"tion for its oper"tion (c) It is nothing else but " single-ph"se, s"lient pole synchronousinduction motor (d) Its squirrel c"ge-rotor is of unsym-metric"l m"gnetic construction in order to v"ry reluct"nce p"th between st"tor "nd rotor 97. A univers"l motor is one which (") c"n be oper"ted either on D.C. or A.C. supply "t "pproxim"tely the s"me speed "nd output (b) c"n be m"rketed intern"tion"lly (c) runs "t d"ngerously high speed on no-lo"d 98. A repulsion motor is equipped with (") slip rings (b) commut"tor
(c) both (") "nd (b) 99. The c"p"citors used in single-ph"se c"p"citor motors h"ve no (") volt"ge r"ting (b) dielectric medium (c) pol"rity m"rking (d) definite v"lue 100. If " D.C. series motor is oper"ted on A.C. supply, it will (") sp"rk excessively (b) h"ve poor efficiency (c) h"ve poor power f"ctor (d) "ll of the "bove