If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of wood C. inject small amounts of CO2 into the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents

If overloading a DC machine becomes necessary in an emergency, you should ____________. A. cool the machine with portable blowers and fans B. hold thermal overload relays open with blocks of wood C. inject small amounts of CO2 into the windings for cooling D. increase the residual magnetism value of windings to reduce eddy currents
by

1 Answer

Answer :

Answer: A
by

Related questions

Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Description : Insufficient brush pressure on a DC motor may cause _______. A. generator overload B. excess residual magnetism C. water vapor absorption D. sparking of the brushes

Last Answer : Answer: D

The illustrated motor fails to start and gives a loud hum when the start button is depressed, your first action should be to __________. EL-0007 A. disassemble the motor to fix the centrifical switch so the start windings will be energized B. push the stop button to deenergize the 'M' coil C. reset the thermal overload D. hold the 'M' contactor closed by hand while wearing electrical safety gloves to get motor started

Description : The illustrated motor fails to start and gives a loud hum when the start button is depressed, your first action should be to __________. EL-0007 A. disassemble the motor to fix the centrifical ... D. hold the 'M' contactor closed by hand while wearing electrical safety gloves to get motor started

Last Answer : Answer: B

The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings

Description : The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the _____________. A. loss of residual magnetism B. absorption of moisture in the insulation C. insulation varnish flaking D. dirt collecting on the windings

Last Answer : Answer: B

One of the generator bearing shells is generally insulated from the end housing in order to prevent _____________. A. rapid brush wear B. residual magnetism leak off C. excessive field winding heat D. circulation of shaft currents

Description : One of the generator bearing shells is generally insulated from the end housing in order to prevent _____________. A. rapid brush wear B. residual magnetism leak off C. excessive field winding heat D. circulation of shaft currents

Last Answer : Answer: D

The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____________. A. designing the contacts to open slowly B. directing the arc into an arc chute C. an inverse timed thermal trip for short circuit currents D. instantaneous magnetic trip for overload currents

Description : The arc resulting from the tripping of a circuit breaker is prevented from damaging the contacts by _____________. A. designing the contacts to open slowly B. directing the arc into an ... an inverse timed thermal trip for short circuit currents D. instantaneous magnetic trip for overload currents

Last Answer : Answer: B

The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual magnetism C. kept warm by using strip or space heaters D. relieved of all capacitive charge by grounding the conductors

Description : The insulation of electric generators during short idle periods should be _____________. A. allowed to cool slowly to ambient temperatures B. flashed with direct current to remove any residual ... using strip or space heaters D. relieved of all capacitive charge by grounding the conductors

Last Answer : Answer: C

When power is restored after a complete power failure, a steering gear pump motor will ____________. A. have to be restarted B. have to be reset C. restart automatically D. trip its overload relays

Description : When power is restored after a complete power failure, a steering gear pump motor will ____________. A. have to be restarted B. have to be reset C. restart automatically D. trip its overload relays

Last Answer : Answer: C

A loss of field excitation to an AC generator while operating in parallel will cause it to ____________. A. absorb more and more load due to decreased armature reaction B. lose its load due to the inherent speed droop built into the governor C. smoke and overload due to field flashover as residual field flux changes polarity D. lose its load, begin to motorize, trip out on reverse power relay, and possibly overspeed

Description : A loss of field excitation to an AC generator while operating in parallel will cause it to ____________. A. absorb more and more load due to decreased armature reaction B. lose its load due to ... polarity D. lose its load, begin to motorize, trip out on reverse power relay, and possibly overspeed

Last Answer : Answer: D

In preparing to take insulation resistance readings on a main generator, the windings should be grounded for about 15 minutes prior to the test to _____________. A. allow accurate zeroing of the meter B. help the windings to cool to ambient temperature C. release any residual capacitive charge from the windings D. help the windings to cool to the same temperature as the ground test connection

Description : In preparing to take insulation resistance readings on a main generator, the windings should be grounded for about 15 minutes prior to the test to _____________. A. allow accurate zeroing of the meter ... the windings D. help the windings to cool to the same temperature as the ground test connection

Last Answer : Answer: C

The armature of a dc machine is laminated to reduce: (A) Eddy current loss (B) Hysteresis loss (C) copper losses (D) friction and windage losses

Description : The armature of a dc machine is laminated to reduce: (A) Eddy current loss (B) Hysteresis loss (C) copper losses (D) friction and windage losses

Last Answer : Ans: A Thinner the laminations, greater is the resistance offered to the induced e.m.f., smaller the current and hence lesser the I2R loss in the core.

The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Description : The purpose of amortisseur windings in a synchronous motor is to ______________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Last Answer : Answer: C

Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Description : Amortisseur windings are installed in a synchronous motor to _____________. A. reduce eddy current losses B. produce a higher power factor C. provide a means for starting D. eliminate arcing between the stator and the rotor

Last Answer : Answer: C

Armature cores in a DC generator are made of laminated steel sheets to _____________. A. fit the curvature of the frame B. increase the hysteresis effect C. reduce eddy current losses D. allow for easy assembly

Description : Armature cores in a DC generator are made of laminated steel sheets to _____________. A. fit the curvature of the frame B. increase the hysteresis effect C. reduce eddy current losses D. allow for easy assembly

Last Answer : Answer: C

Transformer cores are laminated to reduce _____________. A. eddy currents B. secondary flux C. leakage flux D. all of the above

Description : Transformer cores are laminated to reduce _____________. A. eddy currents B. secondary flux C. leakage flux D. all of the above

Last Answer : Answer: A

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 : 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

Last Answer : Answer: D

How is air produced in mechanical draught cooling tower? a) Air Tuyeres b) Propeller fans c) Air blowers d) Louvre

Description : How is air produced in mechanical draught cooling tower? a) Air Tuyeres b) Propeller fans c) Air blowers d) Louvre

Last Answer : Propeller fans

How is air produced in mechanical cooling tower 1 air fan 2 propeller fans 3 air blowers 4 propeller blowers

Description : How is air produced in mechanical cooling tower 1 air fan 2 propeller fans 3 air blowers 4 propeller blowers

Last Answer : 2 propeller fans

How is air produced in mechanical draught cooling tower? A] Air Tuyeres. B] Propeller fans C] Air blowers. D] Louvre

Description : How is air produced in mechanical draught cooling tower? A] Air Tuyeres. B] Propeller fans C] Air blowers. D] Louvre

Last Answer : B] Propeller fans

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 : 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

Last Answer : Answer: B

Voltage build up in an isolated induction generator depends on A. Capacitor bank value B. Residual magnetism of the rotor iron C. Residual magnetism of the stator iron a) A, B b) A, B, C c) B d) A, C

Description : Voltage build up in an isolated induction generator depends on A. Capacitor bank value B. Residual magnetism of the rotor iron C. Residual magnetism of the stator iron a) A, B b) A, B, C c) B d) A, C

Last Answer : Ans: A

In the illustration, 'D' is the symbol for a/an __________. EL-0005 A. thermal overload heater B. portable cable C. fuse D. indicating lamp

Description : In the illustration, 'D' is the symbol for a/an __________. EL-0005 A. thermal overload heater B. portable cable C. fuse D. indicating lamp

Last Answer : Answer: C

In the illustration, the purpose of part B is to _________. EL-0033 A. increase resistance in series with the contacts as they close to prevent arcing B. create a magnetic field in the steel plates that interacts with the arc to cool and extinguish the arc C. cause the contacts to open in the event of an overload D. provide ventilation to the contact when the breaker is close to rated capacity

Description : In the illustration, the purpose of part B is to _________. EL-0033 A. increase resistance in series with the contacts as they close to prevent arcing B. create a magnetic field in the steel ... event of an overload D. provide ventilation to the contact when the breaker is close to rated capacity

Last Answer : Answer: B

The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Description : The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Last Answer : Ans: A

Power necessary to operate the horn relay shown in the illustration ____________. EL-0093 A. comes from each station's magneto B. is supplied from a 115 volt source C. is conducted through the relay's contacts D. also lights lamps 'R' and 'T'

Description : Power necessary to operate the horn relay shown in the illustration ____________. EL-0093 A. comes from each station's magneto B. is supplied from a 115 volt source C. is conducted through the relay's contacts D. also lights lamps 'R' and 'T'

Last Answer : Answer: A

Thermal overload relays are used to protect the motor against over current due to (a) short-circuits (b) heavy loads (c) grounds (d) all of the above

Description : Thermal overload relays are used to protect the motor against over current due to (a) short-circuits (b) heavy loads (c) grounds (d) all of the above

Last Answer : (b) heavy loads

Overload relays are of...... type. (a) induction (b) solid state (c) thermal (d) electromagnetic (e) all above

Description : Overload relays are of...... type. (a) induction (b) solid state (c) thermal (d) electromagnetic (e) all above

Last Answer : (e) all above

Thermal overload relays are used to protect the motor against over current due to?

Last Answer : Thermal overload relays are used to protect the motor against overcurrent due to heavy loads.

If a transformer is connected to a DC source, the transformer will overload at the ____________. A. contacts B. primary coil C. secondary coil D. core

Description : If a transformer is connected to a DC source, the transformer will overload at the ____________. A. contacts B. primary coil C. secondary coil D. core

Last Answer : Answer: B

When an AC or a DC motor fails to start, the FIRST step in troubleshooting should be to check the ____________. A. motor windings for obvious opens B. motor controller leads for continuity C. fuse or circuit breaker D. motor controller leads for grounds

Description : When an AC or a DC motor fails to start, the FIRST step in troubleshooting should be to check the ____________. A. motor windings for obvious opens B. motor controller leads for continuity C. fuse or circuit breaker D. motor controller leads for grounds

Last Answer : Answer: C

The counter EMF produced in the windings of a DC motor is 'zero' when the ____________. A. armature has just begun to turn B. armature is not turning C. motor is almost up to rated speed D. motor is at rated speed

Description : The counter EMF produced in the windings of a DC motor is 'zero' when the ____________. A. armature has just begun to turn B. armature is not turning C. motor is almost up to rated speed D. motor is at rated speed

Last Answer : Answer: B

43 The purpose of providing an iron core in a transformer is to A.Provide support to windings B. Reduce hysteresis loss C. decrease the reluctance of the magnetic path D. reduce eddy current losses

Description : 43 The purpose of providing an iron core in a transformer is to A.Provide support to windings B. Reduce hysteresis loss C. decrease the reluctance of the magnetic path D. reduce eddy current losses

Last Answer : C. Decrease the reluctance of the magnetic path

Universal motors will operate on AC or DC current, and are generally found in _____________. A. portable tools B. large pump motors C. turbo electric main motors D. forced draft fans

Description : Universal motors will operate on AC or DC current, and are generally found in _____________. A. portable tools B. large pump motors C. turbo electric main motors D. forced draft fans

Last Answer : Answer: A

Which of the methods listed is used to start a AC generator turning? A. Residual magnetism remaining in the field poles. B. Residual magnetism remaining in the field coils. C. Residual magnetism remaining in the armature. D. Rotation by a mechanical prime mover.

Description : Which of the methods listed is used to start a AC generator turning? A. Residual magnetism remaining in the field poles. B. Residual magnetism remaining in the field coils. C. Residual magnetism remaining in the armature. D. Rotation by a mechanical prime mover.

Last Answer : Answer: D

In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded for 10 minutes to remove static charges. B. The transformer connections must be made as before with regard to the indicated polarity. C. The iron core of the transformer must be flashed to pre-magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.

Description : In replacing a defective transformer with a new one, which of the following actions must be carried out to insure proper operation of the equipment it serves? A. The secondary leads must be grounded ... magnetize it. D. The iron core must be grounded for 10 minutes to remove any residual magnetism.

Last Answer : Answer: B

Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator to run at 10% of normal speed for 5 minutes C. running the generator at normal speed with the field rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field

Description : Loss of or weak residual magnetism in an alternator or generator can be corrected for by _________________. A. running the rotor in the opposite direction for 5 minutes B. allowing the generator ... rheostat fully counterclockwise D. using a storage battery or battery charger to 'flash' the field

Last Answer : Answer: D

If a magnetic controller contact fails to pick up when the operating coil is energized, one possible cause may be _______________. A. low spring pressure B. low voltage to the coil C. the residual magnetism of the contact faces D. dirty contact faces

Description : If a magnetic controller contact fails to pick up when the operating coil is energized, one possible cause may be _______________. A. low spring pressure B. low voltage to the coil C. the residual magnetism of the contact faces D. dirty contact faces

Last Answer : Answer: B

The electrical energy necessary to power a sound-powered telephone's small vibrating bell is obtained from _________. A. the emergency batteries for the general alarm B. each station's hand-cranked generator C. the emergency switchboard D. normal 115 volt DC supplies

Description : The electrical energy necessary to power a sound-powered telephone's small vibrating bell is obtained from _________. A. the emergency batteries for the general alarm B. each station's hand-cranked generator C. the emergency switchboard D. normal 115 volt DC supplies

Last Answer : Answer: B

Basically, a magnetic amplifier is a saturable reactor with the addition of _____________. A. AC to the bias winding B. variable capacitance to all windings C. eddy current protectors D. a rectifier in the load circuit

Description : Basically, a magnetic amplifier is a saturable reactor with the addition of _____________. A. AC to the bias winding B. variable capacitance to all windings C. eddy current protectors D. a rectifier in the load circuit

Last Answer : Answer: D

Use the concept of operator overloading to overload unary ‘-‘ operator to negate value of variables.

Description : Use the concept of operator overloading to overload unary ‘-‘ operator to negate value of variables.

Last Answer : # include <iostream.h> #include<conio.h> class unary { int x, y, z; public: void getdata (int a, int , int c); void display (void); void operator - (); // overload unary minus. }; ... u. display ( ) ; -u; cout<< " u : " ; u. display ( ) ; }

If a synchronous motor begins to vibrate severely and pull out of synchronism, the cause may be ____________. A. an overload B. an open in the field coils C. no exciter voltage D. all of the above

Description : If a synchronous motor begins to vibrate severely and pull out of synchronism, the cause may be ____________. A. an overload B. an open in the field coils C. no exciter voltage D. all of the above

Last Answer : Answer: D

'A-1', as shown in the illustration, is/are ____________. EL-0017 A. normally-closed overload relay contacts B. a double pole knife switch C. normally-open overload relay contacts D. a single pole knife switch

Description : 'A-1', as shown in the illustration, is/are ____________. EL-0017 A. normally-closed overload relay contacts B. a double pole knife switch C. normally-open overload relay contacts D. a single pole knife switch

Last Answer : Answer: A

Eddy currents are induced in the pole shoes of a D.C. machine due to?

Description : Eddy currents are induced in the pole shoes of a D.C. machine due to?

Last Answer : Eddy currents are induced in the pole shoes of a D.C. machine due to relative rotation between field and armature.

Shading coils are installed on AC full-voltage starters to _____________. A. eliminate contact chatter B. dissipate opening contact arcs C. delay current build up in the holding coil D. protect the motor windings from momentary starting current overload

Description : Shading coils are installed on AC full-voltage starters to _____________. A. eliminate contact chatter B. dissipate opening contact arcs C. delay current build up in the holding coil D. protect the motor windings from momentary starting current overload

Last Answer : Answer: A

Brush sparking during commutation may be caused by ________. A. eddy currents in the armature core B. laminations in the generator field pieces C. induced current opposite to coil inductance D. coil inductance discharge occurring at commutation

Description : Brush sparking during commutation may be caused by ________. A. eddy currents in the armature core B. laminations in the generator field pieces C. induced current opposite to coil inductance D. coil inductance discharge occurring at commutation

Last Answer : Answer: D

On tank vessels with an electrically-driven capstan, the motor should be meggered periodically to test _____________. A. insulation resistance B. eddy currents C. capacitance D. armature reactance

Description : On tank vessels with an electrically-driven capstan, the motor should be meggered periodically to test _____________. A. insulation resistance B. eddy currents C. capacitance D. armature reactance

Last Answer : Answer: A

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 : 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

Last Answer : Answer: A

The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains _____________. A. a magnetic operating coil B. normally open line contacts C. thermal-overload protection D. a momentary-contact start button

Description : The main difference between a motor control circuit containing low voltage protection and low voltage release is that the latter contains _____________. A. a magnetic operating coil B. normally open line contacts C. thermal-overload protection D. a momentary-contact start button

Last Answer : Answer: D

Increasing the load to the secondary windings of a transformer will cause a/an ____________. A. decrease in the primary voltage B. increase in the primary voltage C. decrease in the primary current D. increase in the primary current

Description : Increasing the load to the secondary windings of a transformer will cause a/an ____________. A. decrease in the primary voltage B. increase in the primary voltage C. decrease in the primary current D. increase in the primary current

Last Answer : Answer: D

An open in the armature of a DC motor is suspected, but is not found by visual inspection of the commutator. The next step in troubleshooting this problem is to ________________. A. conduct a bar to bar test of the armature B. visually inspect the armature windings C. conduct an insulation resistance test of the armature D. test the commutator for a ground

Description : An open in the armature of a DC motor is suspected, but is not found by visual inspection of the commutator. The next step in troubleshooting this problem is to ________________. A. conduct a ... windings C. conduct an insulation resistance test of the armature D. test the commutator for a ground

Last Answer : Answer: A