FUNCTION -5 (ELECTRICAL)

151. Electrical leads and insulation on a motor should be painted with
     1. heat-resisting acrylic
     2. heat-resisting aluminum
     3. insulating varnish
     4. insulating white lead

ANS.: C

152. Voltage generator by most AC generators is fed from the machine to the bus by means of
     1. brushes on a commutator
     2. brushes on slip rings
     3. slip rings on a commutator
     4. direct connections from the stator

ANS.: D

153. A circuit breaker differs from a fuse in that a circuit breaker
     1. melts and must be replaced
     2. is enclosed in a tube of insulating material with metal ferrules at each end
     3. gives no visual indication of having opened the circuit
     4. trips to break the circuit and may be reset

ANS.: D

154. Incandescent lamps are classified according to
     1. shape of bulb and type of service
     2. size and style of base
     3. operating voltage and wattage
     4. all of the above

ANS.: D

155. As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to
     1. draw a one-line diagram of the circuitry
     2. test all fuses and measure the line voltage
     3. take megger readings
     4. insulate the apparatus from ground

ANS.: B

156. An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard ship as a
     1. magnetic amplifier
     2. ship’s service alternator
     3. three-wire DC generator
     4. saturable core reactor

ANS.: B

157. The state of charge of a lead acid storage battery is best indicated by the
     1. testing of the individual cell voltages
     2. ampere hour capacity of the battery
     3. specific gravity of the electrolyte
     4. total cell voltages

ANS.: C

158. The first requirement for logical troubleshooting of any system is the ability to
     1. collect all available data on a casualty
     2. recognize normal operation
     3. identify the probable cause of a symptom
     4. isolate the faulty component

ANS.: B

159. The load sharing characteristics of two diesel generators operating in parallel are mostly dependent on their governor
     1. load limit settings
     2. idle speed settings
     3. speed limit settings
     4. speed droop settings

ANS.: D

160. The open circuit voltage of a fully charged lead-acid battery cell is
     1. 5 v
     2. 8 v
     3. 0 v
     4. 3 v

ANS.: C

161. In an AC generator, direct current from a separate source is passed through the windings of the rotor
     1. by means of slip rings and brushes
     2. by means of a commutator
     3. by means of rotating bar magnet
     4. to minimize the danger of arc over

ANS.: A

162. A delayed-action fuse is most frequently used in which of the listed circuits?
     1. lighting circuit
     2. motor circuit
     3. electric heater circuit
     4. radar circuit

ANS.: B

163. Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness?
     1. fill the motor housing with CO2 to inert the space
     2. strap silica gel around the commutator
     3. place heat lamps in the motor housing
     4. cover the equipment with a canvas tarpaulin

ANS.: C

164. A fuse of recommended current and voltage ratings that blows often should be replaced only with a fuse of
     1. the same ratings
     2. higher ratings
     3. higher current and lower voltage rating
     4. lower current and higher voltage rating

ANS.: A

165. Which of the listed conditions is an advantage of a PN diode over a vacuum diode?
     1. longer life
     2. no warm up time
     3. less delicate
     4. all of the above

ANS.: D

166. The freezing point of the electrolyte in a fully charged lead-acid battery will be
     1. higher than in a discharged battery
     2. lower than in a discharged battery
     3. the same as in a discharged battery
     4. higher than in a discharged battery, but the specific gravity will be less

ANS.: B

168. The basic measuring unit of inductance is the
     1. coulomb
     2. ohm
     3. farad
     4. henry

ANS.: D

169. Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?
     1. open the machine on both ends so as to allow the air and dust to escape
     2. be certain that the circuit breaker is opened and tagged on the feeder panel
     3. be certain that the air is clean and as dry as possible
     4. all of the above

ANS.: D

170. The purpose of DC generator brushes is to
     1. neutralize armature reaction
     2. conduct electric current to an outside circuit
     3. convert DC current to AC current
     4. provide excitation to a DC generator

ANS.: B

171. Fuses are rated in
     1. voltage
     2. amperage
     3. interrupting capacity
     4. all of the above

ANS.: D

172. Power transformers are rated in
     1. kilowatts
     2. ampere-turns
     3. kilowatt-volts
     4. kilovolt-amperes

ANS.: D

173. Alternative current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in
     1. ohms
     2. mhos
     3. henrys
     4. farads

ANS.: C

174. A lead-acid battery is considered fully charged when the
     1. electrolyte gasses freely
     2. battery charger ammeter indicates a positive reading
     3. terminal voltage reaches a constant value at a given temperature
     4. specific gravity of all cells reaches the correct value and no longer increases over a period of 1 to 4 hrs.

ANS.: D

175. The insulation resistance of electric equipment and machinery should be tested for the lowest normal insulation values
     1. immediately after shutting down the machine
     2. every time the brush rigging is adjusted
     3. immediately after starting up the machine
     4. every 30 days whether the machine is in use or not

ANS.: A

176. High vacuum diodes, gas-filled diodes, and germanium semiconductor diodes may all be used as
     1. potentiometers
     2. rectifiers
     3. power sources
     4. photocells

ANS.: B

177. The apparent power in a purely inductive circuit is also known as
     1. true power
     2. lead power
     3. induced power
     4. reactive power

ANS.: D

178. Which of the following devices will prevent a DC generator from becoming motorized?
     1. overcurrent relay
     2. motorization trip
     3. reverse power relay
     4. reverse current relay

ANS.: D

179. Which of the following devices will prevent a AC generator from becoming motorized?
     1. overcurrent relay
     2. motorization trip
     3. reverse power relay
     4. reverse current relay

ANS.: C

180. A grounded switch or cable will be indicated by a meg ohmmeter reading of
     1. infinity
     2. zero
     3. being unsteady in the high range
     4. being unsteady in the low range

ANS.:  B