If an AC motor is started and produces 25 horsepower,the K meter eating will increase by: NAS: 18. 65 K 5. Which of the following formulas listed is correct for determining the power? NAS: 6. A magnetic blow out coil in a DC motor controller contractor functions to: NAS: Prevent contact melting 7.
The device most commonly utilizing the principle of electromagnetic induction is: NAS: Transformer 8. A current at which a magnetic-type overload relay tends to trip may be decrease by raising the plunger further into the magnetic circuit Of the relay.This action will: NAS: Increases magnetic pull on the plunger and requires more current to trip the relay 9. A dataset mechanism in a magnetic-type,time delay overload relay functions to: NAS: Prevent the relay from operating when normally large starting currents are encountered 10.
The opposition to the establishment of magnetic lines of force in a is called the circuit's: magnetic circuit NAS: Reluctance 1 1 . The basic control action of a magnetic amplifier depends upon: NAS: Changes in inductance 12.The purpose Of a magnetic type relay is to: NAS: Remotely open and close contacts 13. During it's operation,chattering of the contacts in a circuit breaker,or the humming of the magnetic relay may be caused by: NAS: Overheating of the contractor coil 14.
When troubleshooting a magnetic controller,it is found that the contacts are welded together. The most probable cause is: NAS: Low voltage on the operating coil 15. To correct residual magnetism in a self-excited DC generator,you must: NAS: Insulate the brushes from the commutate and flash the field 16.Before using a millimeter all purpose electric measuring instrument,using internal batteries to supply power for resistance measurements,you should FIRST: NAS: Select the proper resistance range 17.
The twisting action of the force developed by a motor and applied to a haft is: NAS: Torque 18. The field strength of a ship's service DC generator is adjusted by varying the: NAS: Resistance in the field 19. The speed of a squirrel-cage,multi-speed,induction motor,as used aboard ship,is varied by changing the: NAS: Number of connected poles in the stator 20.You are calibrating a millimeter used for electric circuits using its internal batteries to supply power for resistance measurements. However,you are unable to adjust using the adjustment knob. Therefore,you should: batteries in the instrument the pointer to "ZERO" NAS: Replace the 21 .
The polarity of the pole pieces of a self excited DC generator has been lost. Properly flashing the field will result in: NAS: Restoration of proper residual magnetism 22. The most practical method uses for resurfacing a ship's service generator commutate is to: NAS: Use a grinding rig 23.An open shunt field in a direct current machine may be located by connecting the field circuit to an external power source,equal to the rated field voltage or less,and tested with a voltmeter from: NAS: One line terminal to each coil lead succession 24. When using magnetometer to determine which shunt field coil is rounded in a DC machine,you must: NAS: Disconnect each shunt field coil before testing 25. Unnecessary and frequent applications of varnish through the generator windings to repair defective insulation will result in: NAS: Heavy coatings of varnish interfering with heat dissipation 26.
Which of the following statements concerning the general maintenance of a brush less generator is correct? NAS: Accessible generator parts should be wiped with a clean dry rag on periodic basis 27. Moisture accumulating in electric motors and generators windings having a cold insulation resistance greater than 50,000 ohms may be eked outwit internal heat. This heat can be developed by: NAS: Feeding current into the windings at low voltage 28. Which of the following materials is recommended for finishing the slip after grinding or turning? Rings NAS: Crocus cloth 29.Which Of the listed conditions might contribute to the mica Segments Of to wear slower than the commutate bars? A commutate NAS: Using improper carbon brushes 30.
The most common method of locating a loose commutate bar is by: NAS: Sounding each bar with a light weight hammer 31 . With regards to an AC generator connected to the main electrical bus,as the electric dad and power factor change,a corresponding change is reflected in a change of the generator armature reaction-These changes in armature reaction are compensated for: NAS: Voltage regulator 32.Which of the following statements represents an application of a silicon- controlled rectifier? NAS: To provide DC power for a main propulsion motor 33. On some diesel electric ship's,the DC propulsion motor will only attain half speed when the generator fields are fully excited.
Speeds above this are obtained by: NAS: Raising the generator engine speed 34. Raising the generator field excitation to a DC propulsion motor in diesel- electric plant will: NAS: Increase main motor speed 35.The type of protection afforded auxiliaries,vital to the operation of propelling equipment,where automatic restart after a voltage failure would not create a hazard is termed: NAS: High amperage release 36. Which of the following types of motors is often designed for use in factor? Correcting power NAS: Synchronous 37. In testing a three phase delta winding for an open circuit using a magnetometer,you m Just: NAS: Open the delta connections to avoid shunting the phase being tested 38.A temperature instrumentation system for an engine room insole consists of a resistance temperature detector (RED)RA measuring bridge circuit and a meter or alarm circuit.
Which of the following statements is true concerning the measuring bridge circuit? NAS: The resistance bridge is said to be balanced when its output voltage is zero. 39. On AC vessel,which of the following statements represents the most difficult problem components? Involved in obtaining a DC potential suitable for use by NAS: The voltage must be rectified and made ripple free 40.A three-phase alternator is operating at 450 volts,250 amps at 0. 6 power factor. If he power factor increases to 0.
8 the K load potential will NAS: 116. 91 K 41 . Which of the following statements is true concerning a polyphony synchronous propulsion motor? NAS: The motor is started as an induction motor 42. Voltage failure of an AC generator may be cause by: NAS: Failure Of the exciter generator 43. A loss of field excitation to an AC generator while operating in parallel will cause it to: NAS: Lose its load,begin to motorize,trip out on reverse power relay and possible Overspend 44.An AC generator operating in parallel loses its excitation without tripping the recruit breaker,this will: NAS: Cause high currents to be induced in the field windings 45.
A meager is being used to test the insulation of an AC generator. The value of a dry,clean winding will: resistance NAS: Continue to rise as test potential is maintained,becoming fairly steady as the dielectric absorption affect of insulation stabilizes 46. A circuit breaker for a SKEW AC generator is rated 470 amperes full load,continuous current-The percent over current allowed is 1 25%.In reference to this information which of the following will trip the breaker? NAS: Sustained current flow of 590 amperes 7. The voltage developed by an AC turbo generator is controlled by varying NAS: DC excitation to the field 48. A constant output of an AC turbo generator is controlled by varying the: 49.
The voltage output of an AC generator is accurately controlled by: Varying the DC exciter voltage 50. The output voltage of a 440 volt,60 Hz's AC generator is controlled by the:' NAS: Exciter output voltage 51 .The instantaneous reduction of an AC generator,resulting from an Increase In load and prior to the automatic voltage regulator correcting the situation is called voltage: NAS: Dip 52. Which of the following statements,concerning and under compounded DC generator,with an inherent voltage regulation of 10% is correct? NAS: The voltage is 10% greater with no load than with full load 53. Automatic voltage regulators provided on switchboard functions to: NAS: Vary the field excitation to the generators 54.
The most practical way to control the voltage output of an AC generator to vary the: is NAS: Strength of the rotating magnetic field 55. The most inefficient method of voltage reduction,from the standpoint of power loss,even when placed in series with the load,is the use of an: NAS: Resistor 56. Automatic voltage regulators installed on DC generators are use to detect voltage changes and adjust the: NAS: Resistance in the field circuit 57. An electric tachometer receives the engine speed signal from an: NAS: Small generator mounted on the engine 58.
A three phase alternator is operating at 450 volts with the switchboards indicating 300 amps. The K meter currently indicates 163. 6 ammeter K,with a power factor of 0. 7.
If the power factor increases to 0. 8,the K reading would increase by: NAS: 23. Cow 59. On a vessel with turbo electric drive, which of the following conditions loud indicate that the propulsion motor had dropped out synchronization with the propulsion generator? NAS: Excessive vibration of the vessel 60.Moisture damage,as a result of condensation occurring inside of the cargo winch master switches,can be reduced by: NAS: Using strip heaters inside the switch box 61 . Which of the following statements represents the main difference between the relay and a contractor? NAS: Contractors can handle heavier loads than relays 62.
Where a thermal acting breaker is required to be used in an area Of unusually high, low or constantly fluctuating temperature,an ambient encompassing element must be used. This element consists of a: NAS: Second bimetallic element 63.Which of the following statements is correct concerning the maintenance of solid- silver contacts in relays and auxiliary control circuits? They should be filed with a fine cut file when projections extend beyond the contact surface 64. A molded case breaker provides protection against short circuit using a: NAS: Electromagnet 65. Which of the following statements is correct concerning an analog device and a digital device? NAS: The variables in digital system are fixed quantities,and the variable in analog yester are continuous quantities 66.The alarm system for an engine order telegraph uses small Selwyn motors attached to the indicators.
The alarm sound when the rotors are: NAS: Not synchronized,current is flowing and the relays are closed 67. A three-phase,induction type motor experience an open in one phase. Who ICC of the listed automatic protective devices will prevent the machine from being damaged? NAS: Thermal overload relay 68. The main difference been. 'en a motor starting circuit containing a low voltage protection and low voltage release is that the former contains: NAS: Thermal overload-protection 9.
You are using a low voltage source for testing armature coils,a coil short circuit will be indicated by: NAS: Low or zero voltage reading,while the other coils readings will have equal or lower value 70. A shading coil used in an AC magnetic controller,its function is to: NAS: Reduce vibration and noise in the contractor 71 . A low-voltage protection device is used in electrical motor starting NAS: Prevent the motor from restarting automatically equipment to: 72. Silicon diodes that are designed for a specific reverse breakdown voltage become useful as electronic power supply voltage regulators called:NAS: Keener diodes 73. The type of control circuit where the machines and its control are removed from from the line when there is a power failure for its protection and will not permit restarting is called: NAS: under voltage protection 74.
Alternating current develop resistance,inductance and capacitance. The capacitance of individual capacitors is expressed in: NAS: Farads 75. Which of the following statements represents the important factor that must be considered when replacing a faulty diode in the rectifier assembly? NAS: Be certain that the replacement diode is the same polarity as the one removed 6.
