Week 3: DC and Instrumentation Power Flashcards
What is the function of the DC power distribution system?
To provide reliable and continuous power for controls, instrumentation, inverters, and emergency auxiliaries.
What are the subsystems of the DC power distribution system?
Safety-related 125VDC
Non-safety 125VDC
Non-safety 250VDC
What system supplies the DC power distribution system with electricity?
The four 480V Safeguards load centers step down the 4160V supply from the NB buses and supply the DC power distribution system.
Describe the function of the Safety-related 125VDC system.
The four 125VDC buses (NK01-04) take the 480V supply from the NG01-04 load centers and convert it to 125VDC power via a battery charger to support safety-related loads. Each NK bus has a battery backup to ensure uninterrupted power in the event of a NB bus undervoltage.
Describe the function of the Non-safety 125VDC system.
The four 125VDC buses (PK01-04) take the 480V supply from the NG01-04 load centers and convert it to 125VDC power via a battery charger to support Non-safety loads. Each PK bus has a battery backup to ensure uninterrupted power in the event of a NB bus undervoltage.
Describe the function of the Non-safety 250VDC system.
The single 250VDC bus (PJ01) supplies power to the emergency DC oil pumps, specifically:
Generator emergency lube oil pump
Generator emergency seal oil pump
2 SG TDFW emergency lube oil pumps
What are the subsystems of the AC Instrumentation Power Distribution system?
Safety-related 120VAC
Uninterruptible 120VAC
Non-safety 120VAC
Describe the function of the Safety-related 120VAC system.
The four 120VAC buses (NN01-04) supply power for vital instrumentation and control loads. Power is sourced from the Safety-related 125VDC system via an inverter, ensuring that power is not interrupted on a NB undervoltage scenario. Two backup 480V to 120V transformers can supply these buses with electricity if an inverter should fail.
Describe the function of the Uninterruptible 120VAC system.
To provide normal and alternate sources of power to the plant computer.
Describe the function of the Non-safety 120VAC system.
To supply reliable power to all non-safety plant instruments.
