Description : A transformer – (1) converts DC to AC (2) is used to decrease or increase AC voltage (3) converts AC voltage to D.C. voltage (4) converts electrical energy into mechanical energy
Last Answer : (2) is used to decrease or increase AC voltage Explanation: Transformers have made longdistance transmission of electric power a practical reality, as AC voltage can be "stepped up" and ... the loads), voltage levels are reduced by transformers for safer operation and less expensive equipment.
Description : A transformer (1) converts DC to AC (2) is used to decrease or increase AC voltage (3) converts AC voltage to D.C. voltage (4) converts electrical energy into mechanical energy
Last Answer : is used to decrease or increase AC voltage
Description : The purpose of DC generator brushes is to _____________. A. neutralize armature reaction B. conduct electric current to an outside circuit C. convert DC current to AC current D. provide excitation to a DC generator
Last Answer : Answer: B
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
Description : Which of the following converts electric energy into mechanical energy: a. Transformer b. DC generator c. Motor d. AC generator
Last Answer : d. AC generato
Description : Transformer is a device to convert – (1) D.C. to A.C. (2) Low voltage D.C. into high voltage D.C. (3) Low voltage A.C. into high voltage A.C. (4) Mechanical energy into Electrical energy
Last Answer : (3) Low voltage A.C. into high voltage A.C. Explanation: A transformer is an electrical device that transfers energy from one circuit to another by magnetic coupling with no moving parts. It converts high volt-age AC into low voltage AC and vice-versa.
Description : Transformer is a device to convert (1) D.C. to A.C. (2) Low voltage D.C. into high voltage D.C. (3) Low voltage A.C. into high voltage A.C. (4) Mechanical energy into Electrical energy
Last Answer : Low voltage A.C. into high voltage A.C.
Description : AC and DC generators are similar in that they _____________. A. both generate alternating voltages B. both rectify the voltage before delivery C. are constructed at the same physical size for the same kilowatt rating D. both supply three-phase power
Last Answer : Answer: A
Description : On AC vessels, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components? A. A stepdown transformer is ... voltage must be rectified and made ripple free. D. Rectifiers cannot operate with voltage regulators.
Last Answer : Answer: C
Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.
Description : In a DC series circuit, all the conductors have the same ____________. A. power expended in them B. voltage drop across them C. resistance to current flow D. current passing through them
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
Description : Transformers are used onboard ships with AC generators to _____________. A. change frequency B. increase power output to modulating frequency controllers C. decrease power output to modulating frequency ... D. permit higher voltage for electric motor operation and low voltage for lighting circuits
Description : When shipboard electrical distribution circuits are connected in parallel, additional parallel circuits will cause the total circuit resistance to _____________. A. increase, causing a drop in the line current B ... an increase in the line voltage D. decrease, causing an increase in the line current
Description : Moisture accumulating in electric motors and generator windings having a cold insulation resistance greater than 50,000 ohms may be baked out with internal heat. This heat can be developed by ____________. ... an electric welder and feeding it into the armature while running the motor at full speed
Description : A wattmeter is used to determine ____________. A. the power being consumed by electrical equipment B. partial circuit resistance C. current flowing in a circuit D. voltage existing between two points in a circuit
Description : Which of the following is not true: A) An oscillator is a circuit that converts DC to AC B) An oscillator is an amplifier that supplies its own input signal C) All oscillators generate sine waves D) In phase feedback is called positive Feedback
Last Answer : C) All oscillators generate sine waves
Description : The electrical supply applied to the anodes shown in the illustration is _____________. EL-0090 A. low voltage, high current DC B. low voltage, high current AC C. high voltage, low current DC D. high voltage, low current AC
Description : Which of the following statements is true concerning a stepdown transformer in an operating AC power circuit? A. Voltage and current will both be increased. B. Voltage and current will both be decreased C. Voltage decreases as current increases. D. Voltage increases as current decreases.
Description : Speaker is a device that __________. A. convert current variations into sound waves B. none of these C. convert electrical energy to mechanical energy D. convert sound waves into current and voltage
Last Answer : A. convert current variations into sound waves
Description : A switchboard for an AC electrical system requires the use of which of the following devices? A. Frequency meter. B. Ohmmeter. C. Induction voltage regulator. D. Current transformer governor.
Description : During start-up of the circuit shown in the illustration, it is noted that the ends of component 'C' alternately glow and become dark without the tube illuminating. The most probable cause ... start the lamp D. component 'B' contacts are opening and closing thus prohibiting sufficient current flow
Description : The voltage developed by an AC generator is controlled by varying the ____________. A. speed of the prime mover B. AC excitation to the field C. DC excitation to the field D. DC excitation of the voltage regulator
Description : When troubleshooting electronic equipment, you should use a high impedance multimeter ________________. A. to prevent excess current flow through the meter that would damage it B. for AC measurements only ... being tested D. so as not to load down the circuit and obtain erroneous voltage readings
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
Description : Electric cables are formed of stranded wire to ____________. A. increase the current carrying capability for a given size wire B. increase their flexibility C. decrease the weight for a given size wire D. assure good conductivity at junction points
Description : As shown in the illustration, the circuit has been on the line for several days when component 'E1' burns out. The operator receives an alarm, switches over 'B' to energize the standby ... than required for the circuit therefore limiting the current through the alarm relay which will not pick up
Description : An AC supply of 230 V is applied to half wave rectifier circuit. A transformer turns ratio is 20 : 1. Find i) Output DC voltage (ii) Peak Inverse Voltage (PIV)
Last Answer : Solution:
Description : Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a corresponding change is reflected in the generator armature reaction. These changes in ... . governor speed droop setting B. voltage regulator C. balance coil D. phase-balance relay
Description : To increase the frequency of an operating AC generator, you should ____________. A. increase the field excitation B. decrease the field excitation C. increase the number of magnetic poles D. increase the speed of the prime mover
Description : Decreasing the frequency in a capacitive circuit while maintaining a constant circuit voltage, will result in a/an _____________. A. increase in apparent power B. decrease in circuit current C. decrease in capacitive reactance D. decrease in total impedance
Description : The advantage of AC over DC is that (a) it contains more electrical energy (b) it is free from voltage fluctuations (c) it generation costs much less (d) it can be transmitted over long distances with minimum power loss
Last Answer : Ans:(d)
Description : DC motors converts electrical into ___ energy. A. Mechanical B. Wind C. Electric D. None
Last Answer : A. Mechanical
Description : A solid-state circuit is inoperative; the FIRST action that should be taken is to ____________. A. wiggle all the components to check for loose connections B. check all the resistors C. change all transistors D. check the DC supply voltage
Description : Humming or buzzing of electric contacts is a symptom of ____________. A. low voltage on the operating coil B. power failure to the operating coil C. a control circuit ground D. a control circuit overload
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
Description : Voltage failure of an AC generator may be caused by ____________. A. failure of the exciter generator B. a tripped bus circuit breaker C. high mica segments on the stator bus bar D. excessive prime mover speed
Description : The device used for converting mechanical energy into electrical energy is called a/an (a) cell (b) transformer (c) dynamo (d) electric motor
Last Answer : Ans:(c)
Description : Which of the following devices converts electrical energy into mechanical energy? (a) Dynamo (b) Transformer (c) Electric motor (d) Inductor
Description : Section II of the circuit shown in the illustration is the ____________. EL-0085 A. voltage regulator B. filter C. rectifier D. voltage transformer
Description : When reading electrical motor controller diagrams, it helps to know that ____________. A. current paths in the control circuit are drawn as heavy lines and in the power circuit as lighter lines B. current ... subject to 500 volts or greater are drawn as light lines and below 500 volts as heavy lines
Description : A galvanometer is an instrument used to measure ___________. A. thickness of galvanized metal B. resistance of electrical wiring insulation C. very small amounts of current or voltage D. quantity of galvans in an electric circuit
Description : What would not increase voltage and generate an electrical current?
Last Answer : Need answer
Description : The instantaneous reduction in voltage of an AC generator, resulting from an increase in load, and prior to the automatic voltage regulator correcting the situation, is called voltage ____________. A. droop B. drop C. dip D. regulation
Description : Can transformer convert AC to DC?
Last Answer : No, Transformer cannot convert AC to DC.
Description : One method of testing for a reversed shunt field coil in a DC generator or motor is by connecting the field to a direct current source, at reduced field rated voltage, and test for ... placed near each field C. test lamp across adjacent fields D. copper jumper across the interpole connections
Description : An equalizing connection between two compound-wound DC generators when paralleled, serves to _____________. A. reverse the polarity of the incoming generator as the series field weakens B. automatically ... the series field of the incoming generator D. parallel the series fields of the generators
Description : What is the function of a fuse wire? (a) To prevent an unduly high electric current from passing through a circuit (b) To increase the current supply (c) To decrease the current supply (d) To stabilise the voltage
Last Answer : Ans:(a)
Description : When securing an AC generator, you should FIRST ___________. A. open the generator circuit breaker B. switch the voltage regulator to 'manual' C. decrease the field excitation to minimum D. reduce the load on the unit