Power Management Systems Flashcards
7 cards from real DPO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Power Management Systems flashcards as text
What is the function of an Automatic Voltage Regulator (AVR) on a DP vessel's generator?
Answer: It maintains the generator's output voltage at the correct level by controlling field excitation, regardless of load changes
The AVR continuously adjusts generator field excitation to keep output voltage stable, which is critical for thruster drive performance during DP operations.
Which parameter does the governor system control on a DP vessel's diesel generator?
Answer: Engine speed (RPM), which determines output frequency on the AC busbar
The governor controls engine speed/RPM, which in turn determines the AC frequency output of the generator, keeping it at the required 60 Hz (US) or 50 Hz.
Why is it important to connect additional generators before commencing DP operations in harsh environmental conditions?
Answer: Higher sea states demand greater thruster output, increasing power demand and reducing available spinning reserve if too few generators are running
Harsh conditions increase thruster demand significantly; having extra generators online ensures adequate spinning reserve so a single generator trip does not result in loss of position.
What is the risk of connecting parallel generators with different governor droop settings on a DP vessel?
Answer: Unequal load sharing between generators, potentially overloading one unit while the other runs lightly loaded
Mismatched droop settings cause generators to respond differently to load changes, leading to unequal kW sharing, which can overload one generator and cause it to trip.
What does 'preferential tripping' refer to in a DP vessel's power management system?
Answer: An automatic sequence that disconnects lower-priority consumers in a defined order to prevent generator overload before it causes a blackout
Preferential tripping automatically sheds loads in priority order (lowest priority first) to keep generators within safe limits and prevent a blackout.
What causes reactive power (kVAr) to circulate between generators running in parallel, and why is it a concern on a DP vessel?
Answer: Mismatched AVR settings cause generators to have different excitation levels, driving reactive current to circulate, which can overheat generator windings
Mismatched AVRs cause differing excitation voltages; the resulting reactive current circulation increases generator winding temperature and can lead to overloading.
What is the consequence of a 'reverse power' condition on a DP vessel's generator?
Answer: The generator is being motored by the busbar, meaning the engine is no longer supplying power; it can damage the engine and should trigger protection relay tripping
Reverse power means the generator is consuming rather than supplying power, motoring the diesel engine in a way it is not designed for; reverse power relays trip the generator breaker to protect the engine.