Document: NUREG-0800
Document ID: 81256f55-72dd-4777-9472-f373c71c4554
Document Type: srp
Title: AC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550065.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
nclude a review of interconnections of redundant buses, buses and loads, and buses and power supplies; physical arrangement of redundant switchgear and power supplies; criteria and bases governing the installation of electrical cables for redundant power systems; and proposed sharing of the ac power system between units at the same site. 3. Onsite and Offsite Power System Independence In evaluating the independence of the onsite power system with respect to the offsite power system, the scope of review extends to the station distribution load centers that are powered from the unit auxiliary transformers and the startup transformers (considered for the purposes of this SRP section as the offsite or preferred power sources). It includes the supply breakers connecting the "low" side of these transformers to the distribution buses. This evaluation includes a review of the electrical protective relaying circuits and power supplies to ensure that, in the event of a loss of offsite power, the independence of the onsite power system is established through prompt opening of isolation-feeder breakers. 4. Standby Power Supplies Design information and analyses demonstrating the suitability of the diesel generators as standby power supplies are reviewed to ensure that the diesel generators have sufficient capacity, capability, and reliability to perform their intended function. This will include an 8.3.1-3 Revision 3 - March 2007 examination of the characteristics of each load and the length of time each load is needed, the combined load demand connected to each diesel generator during the "worst" operating condition, automatic and manual loading and unloading of each diesel generator, voltage and frequency recovery characteristics of the diesel generators, continuous and short-term ratings for the diesel generators, acceptance criteria with regard to the number of successful diesel generator tests and allowable failures to demonstrate acceptability, and starting and load