Aux 1 Unit 14 Switchboard Flashcards

In what type of applications are cartridge type fuses commonly used?

B) In a wide range of applications, including household appliances, industrial machinery, and automotive systems, due to their reliability and safety

Which of the following parameters must be checked to ensure compatibility before connecting a shore supply to a vessel’s distribution system?

B) The voltage of the shore supply

Why is an overcurrent relay needed on a main distribution switchboard for a.c. generators?

C) To protect the generator from damage by disconnecting it in case of excessive current flow, which could cause overheating or damage to windings

What is a likely outcome if the shore supply’s available power (capacity) is insufficient for the vessel's needs?

B) The shore supply could become overloaded, leading to tripping of circuit breakers, power outages, or damage to the shore-side infrastructure.

Why does a fuse used in a motor circuit generally have a higher current rating than one used in a lighting circuit?

A) Motors typically draw higher currents, especially during startup, and the fuse must be capable of handling these surges without blowing.

Before connecting the shore power, what should be verified about the frequency of the shore supply?

A) It matches the vessel’s required frequency (e.g., 50Hz or 60Hz)

Which safety device must be operational and checked before connecting to shore power?

B) The shore power circuit breaker and fuses

What is the primary advantage of using a cartridge type fuse over a traditional fuse with a glass envelope?

A) The cartridge type fuse can handle higher voltage and current ratings due to its robust construction and better arc containment.

What happens to a cartridge type fuse after it has operated (blown)?

B) It must be replaced, as it is a single-use protective device

What precaution must be taken before disconnecting the emergency generator after main power has been restored?

B) Ensure that all essential services have been successfully transferred to the main power supply

Why is an under-voltage relay necessary on a generator's main distribution switchboard?

B) To protect the generator and connected equipment from operating under low voltage conditions, which can cause inefficient operation and potential damage

Which device on a main distribution switchboard is used to protect a.c. generators from overload by tripping the generator offline if the current exceeds a preset value?

A) Overcurrent relay

Why is it important to monitor the voltage and frequency of the main generators when restoring power to the emergency switchboard?

B) To ensure that the restored power supply is stable and within acceptable limits, preventing potential damage to sensitive equipment

What could happen to transformers on the vessel if they are operated on a 50Hz supply instead of the intended 60Hz supply?

B) The transformers may overheat due to higher current draw and increased core losses, leading to potential damage.

Which device is used on the switchboard to automatically disconnect the generator if the frequency deviates significantly from the nominal value?

A) Under/over-frequency relay

Why is it important to gradually transfer the load from the emergency generator back to the main generators when restoring power?

B) To ensure that the main generators can handle the load without tripping or causing voltage fluctuations

What is a cartridge type fuse primarily composed of?

B) A cylindrical ceramic or glass tube containing a metal wire or strip that melts when excessive current flows through it

What is the purpose of the loss of excitation relay in generator protection?

C) To protect the generator by disconnecting it if the excitation is lost, preventing uncontrolled operation and potential damage

What device on the emergency switchboard automatically transfers the load from the main switchboard to the emergency generator in the event of a power failure?

B) Automatic Transfer Switch (ATS)

What impact might running a 60Hz vessel on a 50Hz supply have on the vessel’s lighting system?

B) The lights may flicker or operate at reduced brightness due to the lower frequency, leading to potential stress on the lighting components.

Why is it essential to check the voltage of the shore supply before connecting it to the vessel?

A) To ensure it matches the vessel’s distribution system voltage, preventing overvoltage or undervoltage conditions that could damage onboard equipment.

Why is a cartridge type fuse typically enclosed in a ceramic or glass tube?

B) To provide insulation and containment of the arc and molten metal when the fuse operates, enhancing safety

Why is an under/over-frequency relay critical in protecting a generator?

B) To ensure the generator operates within the correct frequency range, preventing damage to the generator and connected equipment due to incorrect frequency

What could happen if the frequency of the shore supply does not match the vessel’s distribution system?

B) The vessel's electrical equipment may malfunction or operate inefficiently, leading to potential damage.

Why is it important to verify the shore supply's available power (capacity) before connecting it to the vessel?

A) To ensure the shore supply can handle the vessel's load without overloading, which could lead to power outages or damage to the shore supply infrastructure.

Which component on the emergency switchboard provides critical protection by disconnecting faulty circuits to prevent damage to the system?

A) Protective relays

Why is a reverse power relay important when generators are operated in parallel?

B) To prevent a generator from consuming power instead of supplying it, which could lead to mechanical damage or inefficiency

If an incorrect shore supply connection results in a blackout on the vessel, what might be a necessary corrective action?

A) Immediately disconnect the shore supply and revert to the vessel's emergency generator until the issue is resolved.

What is a potential consequence of connecting a shore supply with a voltage that is too high for the vessel’s distribution system?

B) The vessel's electrical equipment could suffer overvoltage damage, potentially leading to failure or even fire hazards.

What device is used to detect and protect a generator from reverse power flow when operating in parallel with other generators?

A) Reverse power relay

What device is used to protect a generator from low voltage situations that could result in inefficient operation or damage to electrical equipment?

A) Under-voltage relay

Which of the following is a critical item to check before connecting a shore power supply to a vessel?

B) The voltage compatibility between the shore supply and the vessel’s electrical system

What should be checked regarding the shore power cable before connecting it to the vessel?

B) The insulation condition of the cable, ensuring there are no signs of wear, damage, or exposure

Why is it important to check the grounding (earth) connection before connecting to shore power?

B) To confirm the system is safely grounded, preventing potential electric shocks or equipment damage

Which component on the emergency switchboard is responsible for controlling and distributing power to essential services?

B) Emergency switchboard busbars

Which switchboard device is responsible for disconnecting the generator in the event of a loss of field excitation, thereby preventing damage due to uncontrolled generator operation?

A) Loss of excitation relay

What long-term damage could occur if a vessel repeatedly connects to an incompatible shore supply without proper checks?

B) Repeated exposure to incorrect voltage or frequency could lead to cumulative damage to the vessel’s electrical systems, shortening equipment lifespan and increasing maintenance costs.

What is a likely effect on motor-driven equipment if a 60Hz vessel is connected to a 50Hz shore power supply?

B) The motors will run slower, potentially causing overheating and reduced efficiency.

Before connecting to shore power, what final check should be made?

B) Verify that all onboard systems are ready to accept shore power, and any non-essential loads are turned off during the connection process to avoid a power surge

In a line diagram of an emergency switchboard, which component ensures that the emergency generator does not operate in parallel with the main generators?

A) Circuit breaker interlock

What is the first step in restoring main electrical power to the emergency switchboard after a blackout?

B) Ensure the main generators are started and synchronized with the busbars

What role does the emergency battery bank play in the emergency switchboard arrangement?

B) It offers backup power to essential services if the emergency generator fails or during the time before the generator starts

What might occur if the shore supply frequency does not match the vessel’s electrical system?

B) Electrical motors and other frequency-sensitive equipment may overheat, malfunction, or be damaged due to improper operation at the incorrect frequency.

What should be verified about the shore supply capacity before connecting to the vessel?

A) The supply capacity is equal to the vessel's maximum demand to avoid overloading the shore supply

What is the function of the metal end caps on a cartridge type fuse?

B) To facilitate easy installation and ensure a secure electrical connection within the fuse holder

What characteristic is important for a fuse used in a motor circuit that is less critical in a lighting circuit?

B) Delayed or time-delay (slow-blow) characteristic to handle inrush currents without blowing

Why might a standard fast-acting fuse be more suitable for a lighting circuit compared to a motor circuit?

C) Lighting circuits have relatively stable and lower current demands, so a fast-acting fuse provides effective protection without the need for delay.

How does a cartridge type fuse protect an electrical circuit?

B) By interrupting the circuit when the internal metal wire or strip melts due to excessive current, thereby preventing damage to the circuit

What could be a consequence of connecting a shore supply with a lower voltage than the vessel’s system requires?

B) The vessel's equipment may operate inefficiently or fail to start, potentially leading to undervoltage damage or operational issues.

Which of the following is a main component of an emergency switchboard?

B) Emergency generator

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