Which of the following statements describes what will occur if the motor shown in the illustration is required to carry 150% of full load? EL-0056 A. The primary counter emf will be increased. B. The stator current will increase. C. The slip will decrease. D. The slip value, stator current curve, and torque curve will all coincide.

1 Answer

Answer :

Answer: B

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Description : 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

Description : An increase in the amount of current flow through the armature of a shunt motor is the final result of a/an _____________. A. increase in the load on the motor B. decrease in the load on the motor C. increase in counter EMF D. decrease in armature torque

Last Answer : Answer: A

Description : As shown in the illustration, the purpose of the item labeled 'Z', in assembly No. 2, is to _____________. EL-0001 A. keep the rotor in balance B. align the rotor to the stator C. dynamically balance the rotor D. cool the motor

Last Answer : Answer: D

Description : The purpose of the item labeled 'Z' in assembly No. 2, shown in the illustration is to _____________. EL-0001 A. keep the rotor in balance B. align the rotor to the stator C. dynamically balance the rotor D. cool the motor

Last Answer : Answer: D

Description : Regarding an induction motor, the power developed by the rotor automatically adjusts itself to the _____________. A. power required to drive the load B. speed required to drive the load C. current flow in the motor stator D. torque developed by the rotating field

Last Answer : Answer: A

Description : Which of the following statements is correct concerning the motor performance curves and data table shown in the illustration? EL-0006 A. The motor RPM at full load is 1737 RPM. B. The motor draws 12.62 kw ... If the motor was developing 10 HP its power factor would be 0.92. D. All of the above.

Last Answer : Answer: D

Description : Which of the following statements is true concerning the operating characteristics of a squirrel-cage motor? A. Rotor slip is dependent upon the motor load. B. An increase in motor load results in ... results in less generated current. D. A decrease in rotor speed produces a weaker magnetic field.

Last Answer : Answer: A

Description : 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

Description : In the illustration, the diode between terminals 16 and 17 is to _________. EL-0046 A. insure that the voltage across the governor coil (EG-3P) never exceeds .6 VDC B. compensate for the ... heating up C. protect the electronic governor from counter EMF D. act as a filter to prevent hunting

Last Answer : Answer: C

Description : Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz. What will be the frequency of the rotor induced emf? (A) 10 Hz. (B) 50 Hz. (C) 1 Hz. (D) 2500 Hz.

Last Answer : Ans: C Given : s = 0.02 ; f = 50 Hz Therefore, frequency of rotor induced emf = s f = 0.02 x 50 = 1.0 Hz

Description : As shown in the illustration, which of the following conditions will occur as a result of a momentary loss of power? EL-0017 A. The motor will automatically restart when power is restored. B. 'H-4' will open, ... the motor. D. 'A-1' or 'A-2' will open, necessitating a manual restarting of the motor.

Last Answer : Answer: B

Description : The purpose of 'R6' in the winch circuit shown in the illustration is to _______________. EL-0102 A. maintain dry conditions within the winch brake box B. keep the series field current at ... to assist the winch in stopping D. limit the armature current during lowering operation with heavy loads

Last Answer : Answer: C

Description : Which of the following actions must be carried out prior to closing the alternator circuit breaker according to the graph shown in the illustration? EL-0002 A. Increase the alternator voltage. B. Decrease the line voltage. C. Increase the line voltage. D. Decrease the line frequency.

Last Answer : Answer: A

Description : Erratic operation of the devices represented in the diagrams shown in the illustration could be traced to ____________. EL-0092 A. improper contact at 'R' slip rings or 'S' connections B. a low three- ... . improper contact at 'S' slip rings or 'R' connections D. a high three-phase voltage supply

Last Answer : Answer: A

Description : In actual applications, electrical connections to 'R1-R2' of figure 'A' and to 'R1-R2- R3' of figure 'B' shown in the illustration are made by ______________. EL-0092 A. soldered contacts B. spliced and taped connections C. slip rings and brushes D. solderless crimp-on connectors

Last Answer : Answer: C

Description : Which of the following statements is true concerning the motor controller diagram shown in the illustration? EL-0023 A. Terminal 'T2' is hot only on high speed. B. Both indicating lights will be lit on ... high speed operation only. D. 'L2' is always connected to 'T2' whenever the motor is running.

Last Answer : Answer: D

Description : When the motor shown in the illustration is running and the stop button is pushed, which of the following statements will hold true? EL-0010 A. Coil 'M' will now be energized. B. Coil 'CR' will now be energized. C. Contact 'M' will close as contact 'CR' opens. D. Contacts 'M' and 'CR' will open.

Last Answer : Answer: D

Description : What type of circuit is on card 'A0AA2' at coordinate '29Q' shown in the illustration? EL-0099 A. Operational amplifier B. Digital logic inverter C. Square wave pulse generator D. Binary counter

Last Answer : Answer: A

Description : Component 'D' in section 'I' shown in the illustration represents a ____________. EL-0093 A. selector switch B. vibrating reed indicator C. junction box D. ring counter

Last Answer : Answer: A

Description : The circuit shown in the illustration functions as a ____________. EL-0087 A. pulse trigger circuit for an operational amplifier B. three stage, high gain class 'A' amplifier C. binary ripple counter or shift register D. free running multivibrator

Last Answer : Answer: C

Description : The rotor of a synchronous motor operates in synchronism with the rotating field because ______________. A. of the amortisseur windings B. the rotor is magnetically locked into step with the ... field strength varies directly with rotor slip D. the stator flux rotates in the opposite direction

Last Answer : Answer: B

Description : A synchronous motor maintains synchronism with the rotating field because _____________. A. field strength varies directly with rotor slip B. DC current applied to the rotor coils causes the rotor ... the flux created by the excitation current D. the stator flux rotates in the opposite direction

Last Answer : Answer: B

Description : In Induction motor Slip frequency of rotor current, when rotor speed is Nr. Then rotor producing slip field rotates with respect to stator is a) Slip frequency b) Nr c) Ns d) None

Last Answer : Ans: Ns

Description : The current from the stator of an alternator is taken out to the external load circuit through (A) slip rings. (B) commutator segments. (C) solid connections. (D) carbon brushes.

Last Answer : (C) solid connections.

Description : When an operating motor is connected to the controller shown in the illustration, the a path of current flow through the circuit is ____________. EL-0010 A. 'L1', stop button, start button, coil 'CR', 'L2' B. 'L1' ... L2' D. 'L1', stop button, start button, 'CR' contact, 'M' contact, 'CR' coil, 'L2'

Last Answer : Answer: B

Description : The purpose of the 'heater resistors' for the winch circuit shown in the illustration is to _______________. EL-0102 A. limit the current in the heater circuit B. dispel moisture in the ' ... panel C. keep the winch brake housing below the dew point D. maintain winch motor operating temperature

Last Answer : Answer: B

Description : Which device will stop the motor shown in the illustration in case of a short-circuit (high current) motor overload? EL-0080 A. 'F' B. 'G' C. 'H' D. 'I'

Last Answer : Answer: A

Description : If the total source voltage of the three-wire distribution system shown in the illustration is 240 volts, what is the voltage across load L5? [ NOTE: Kirchhoff's voltage and current laws apply ] EL-0075 A. 110.4 volts B. 112.2 volts C. 113.0 volts D. 114.8 volts

Last Answer : Answer: D

Description : If the total source voltage of the three-wire distribution system shown in the illustration is 240 volts, what is the voltage across load L1? [NOTE: Kirchhoff's voltage and current laws apply.] EL-0075 A. 110.4 volts B. 112.2 volts C. 113.3 volts D. 114.8 volts

Last Answer : Answer: D

Description : If the total source voltage of the three-wire distribution system shown in the illustration is 240 volts, what is the voltage across load L2? [NOTE: Kirchhoff's voltage and current laws apply.] EL-0075 A. 110.4 volts B. 112.2 volts C. 113.0 volts D. 114.8 volts

Last Answer : Answer: C

Description : If the total source voltage of the three-wire distribution system shown in the illustration is 240 volts, what is the voltage across load L3? [NOTE: Kirchhoff's voltage and current laws apply.] EL-0075 A. 110.4 volts B. 112.2 volts C. 113.0 volts D. 114.8 volts

Last Answer : Answer: B

Description : What is the direction of current through the load resistor in the circuit shown in the illustration? EL-0085 A. Always from point 'Z' to the grounded end. B. Always from the grounded end to ... on the instantaneous polarity at point 'W'. D. It cannot be determined without a directional ammeter.

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Description : The device in figure 'B' shown in the illustration can be used to control an AC load yet maintain its high gain by ______________. EL-0091 A. connecting the load to the output side of the ... connecting the load to the input side of the bridge D. reversing the current flow through the bias winding

Last Answer : Answer: C

Description : What type of current would flow through the load in figure 'B' shown in the illustration? EL-0091 A. AC only B. DC only C. AC or DC depending on control winding polarity D. AC or DC depending on instantaneous polarity of the source

Last Answer : Answer: B

Description : The purpose of the bias winding in figure 'B' shown in the illustration is for ____________. EL-0091 A. changing the direction of current in the control winding B. setting the operating point of the ... use of either AC or DC in the load circuit D. changing the direction of current through the load

Last Answer : Answer: B

Description : Using illustrated chart, when will the power factor be least efficient? EL-0006 A. When the motor is operating at full load. B. When the percentage of slip is greatest. C. When there is no load on the motor. D. the power factor is the same from no-load to locked rotor.

Last Answer : Answer: C

Description : The purpose of resistor bank 'R1-R5' in the winch circuit shown in the illustration is to ______________. EL-0102 A. limit armature current in lower and 'series field' current in hoist to ... required speeds D. regulate the strength of the brake solenoid 'B1-B2' in both directions of operation

Last Answer : Answer: C

Description : A synchronous motor is operating on no-load at unity power factor. If the field current is increased, power factor will become (A) Leading & current will decrease (B) Lagging & current will increase. (C) Lagging & current will decrease. (D) Leading & current will increase.

Last Answer : Ans: A Initially synchronous motor is operating at no load and unity power factor. When field current increases, the excitation will increase. Therefore, p.f will be leading and current will be I CosĪ¦ < I

Description : The purpose of a 'slew rate controller' in a circuit such as shown in the illustration is to ______________. EL-0096 A. limit the rate of change of a signal B. introduce a 'live zero' ... linear input into a non-linear output D. reduce air pressure to a value required by a combination circuit

Last Answer : Answer: A

Description : A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are a) 0.02, 600 W b) 0.04, 580 W c) 0.04, 1160 W d) 0.04, 1200 W

Last Answer : Ans: 0.04, 1160 W

Description : In the illustration, the signal from the device connected to terminals 18 and 19 is __________. EL-0046 A. prime mover speed feedback B. loss of control alarm when comparing with the input signal ... slip between the prime mover and the alternator D. to shut down the prime mover if overspeeding

Last Answer : Answer: A

Description : In order to decrease the resistance of the 50K pot located at '21Q/R' shown in the illustration, the wiper of the actual component must be moved ____________. EL-0099 A. to the left B. to the right C. clockwise D. counterclockwise

Last Answer : Answer: D

Description : In a 15 HP induction-type motor with a cage rotor, the current required at standstill to produce starting torque is approximately ____________. A. half the full load current B. equal to the full load current C. five times the full load current D. ten to twenty times the full load current

Last Answer : Answer: C

Description : As shown in the illustration, which listed action will occur first when push button 'Q' is depressed? EL-0017 A. Contacts 'H-1', 'H-2' and 'H-3' close. B. Contact 'H-4' closes. C. Operating coil 'C' energizes. D. Switch 'R' opens.

Last Answer : Answer: C

Description : Which of the listed conditions occur when '4th point lower' is selected on the winch shown in the illustration? EL-0102 A. Master switch contacts '3', '4', '6', '8', '9', & '10' close. B. Contactors '2, 3, & 4M' and ' ... , '7', '8', and '9' close. D. Contactors '1 & 3M' and '1, 2, & 3A' pick up.

Last Answer : Answer: B

Description : Which of the listed conditions occur when selection is made for 'third point hoist' on the winch shown in the illustration? EL-0102 A. Master switch contacts '5', '6', '7', '8', and '9' close. B. Contactors '2M', ' ... ' and '2A' drop out. D. Master switch contacts '3','4', '6', '8', and '9' close.

Last Answer : Answer: D