Set 9 - MET online questions for marine engineer MEO class4 exam

1. A semiconductor that decreases in resistance with an increase in temperature is known as a __________.
resistor
thermistor
diode
thermopile

2. In a diesel electric plant, raising the generator's field excitation will cause the DC propulsion motor to __________.
increase in speed
decrease in speed
affect generator speed only
affect main motor speed if done in conjunction with higher generator engine speeds

3. Which of the following statements best describes the material known as varnished cambric?
Felted asbestos sealed with varnish.
Cotton cloth coated with insulating varnish.
Rubber insulation coated with a layer of tin.
Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.

4. A synchronous motor maintains synchronism with the rotating field because _____________.
field strength varies directly with rotors Slip
DC current applied to the rotor coils causes the rotor magnets to lock in with the rotating flux of the stator
the stator poles are dragged around due to the flux created by the excitation current
the stator flux rotates in the opposite direction

5. A low voltage protection circuit is used in electric motor starting equipment
Trip circuit contractor when the motor overspeed due to low voltage
Trip circuit contractor when the motor develops short circuit due to low voltage
Allows the motor to restart automatically on restoration of voltage without manual resetting
prevent motor from restarting automatically

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