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WorksheetsELECTRO 3 Midterm Summative Exam
Total questions: 25
Worksheet time: 13mins
What is the primary function of the Ship's Main Switchboard (MSB)?
To power critical systems during blackouts
To connect the ship to port electricity only
To synchronize multiple generators
To distribute power from generators to all shipboard systems
Which component of the MSB is responsible for matching voltage, frequency, and phase before connecting multiple generators?
A. Synchronizing Panel
B. Feeder Panels
C. Circuit Breakers
D. Protection Devices
Which switchboard type is specifically designed to maintain power to critical systems during a blackout?
Emergency Switchboard
Main Switchboard
Generator Paralleling Panel
Shore Power Switchboard
Protection devices in the MSB serve what primary function?
Provide overload, short-circuit, and earth fault protection
Control generator synchronization
Direct power to various ship systems
Display voltage and current readings
The feeder panels in an MSB are responsible for:
Directing power to specific ship systems
Conducting power through the main busbars
Synchronizing multiple generators
Monitoring generator parameters
Circuit breakers in the MSB are analogous to:
Traffic lights that stop overloads
Customs gates for external power
Weather monitoring instruments
Runways for power distribution
The Shore Power Switchboard's primary function is to:
Connect ship to port electricity safely
Power emergency systems
Monitor generator parameters
Synchronize multiple generators
What is the primary purpose of cascade protection in shipboard electrical systems?
To reduce the number of protection devices needed
To shut down all circuits simultaneously during a fault
To increase power consumption efficiency
To isolate only the faulty circuit while maintaining operation of healthy circuits
Which term is also used to describe cascade protection?
System isolation
Power distribution
Circuit breaking
Preferential tripping
What happens if lower-level protection devices fail in a cascade system?
Auxiliary power systems activate
The fault remains unprotected
Higher-level breakers will trip
The entire system shuts down immediately
What is remanence in magnetic materials?
The ability of a material to conduct electricity
The magnetization remaining after removing an external magnetic field
The strength of a magnetic field at its poles
The rate at which a material becomes demagnetized
Which of the following best describes the relationship between magnetic poles?
All poles attract each other equally
Like poles attract, unlike poles repel
Like poles repel, unlike poles attract
Poles have no effect on each other
How can lost remanence in a generator be restored?
By cooling the generator to very low temperatures
Through exposure to strong radioactive materials
By replacing the rotor core entirely
Using a 12V battery to flash the exciter field
What is coercivity in magnetic materials?
The rate of magnetic field decay
The field strength needed for demagnetization
The speed of electron spin alignment
The temperature at which magnetism is lost
What happens in a generator's excitation loop?
The generator gradually loses all magnetism
The rotor speed continuously increases
The temperature rises until shutdown
Small voltage powers AVR to boost magnetic field
What is the function of circuit breakers in generator protection systems?
To monitor voltage fluctuations only
To permanently disconnect faulty circuits
To automatically open the circuit when a fault is detected
To regulate current flow during normal operation
Which of the following is a characteristic of protective relays?
They cannot be reset once triggered
They monitor electrical parameters and signal breakers
They only detect overcurrent conditions
They physically break the circuit like fuses
In system zone protection, which component changes voltage levels and requires protection from internal faults?
Generator
Busbar
Transmission Line
Transformer
Which protection coordination principle is analogous to airbags deploying instantly during a crash?
Speed
Reliability
Selectivity
Sensitivity
In an AC induction motor, which component creates the rotating magnetic field?
Shaft
Bearings
Stator
Frame
Which type of AC induction motor is most commonly used in industrial applications due to its higher efficiency?
Single-phase motor
Wound rotor motor
Direct-coupled motor
Three-phase motor
What starting method would be most appropriate for a large AC induction motor where controlled acceleration is critical?
Direct-On-Line (DOL) starter
Variable Frequency Drive (VFD)
Manual starter
Basic contactor
Which protection device automatically breaks the circuit when current exceeds safe levels and can be reset?
Fuse
Ground fault protector
Thermal sensor
Circuit breaker
In the context of AC induction motors, what is the primary function of bearings?
Generate magnetic field
Provide electrical insulation
Support smooth rotation
Convert electrical energy
Choosing between a motor and a generator depends on the desired function. Which would you choose and why?
A motor, because it converts electrical energy into mechanical energy.
A generator, because it stores electrical energy for later use.
A motor, because it generates electricity from motion.
A generator, because it converts mechanical energy into heat energy.
