Document: NUREG-0800
Document ID: 88ed0d92-9d6e-40b1-b060-6d7334f66eb8
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070710478.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8
CFR Part: 
CFR Title: 

Content:
ltage requirements of the Class 1E loads at all onsite system distribution levels. b. Two separate time delays should be selected for the second level of undervoltage protection based on the following conditions: i. The first time delay should be long enough to establish the existence of a sustained degraded voltage condition (i.e., something longer than a motor-starting transient). Following this delay, an alarm in the control room should alert the operator to the degraded condition. The subsequent occurrence of a safety injection actuation signal (SIAS) should immediately separate the Class 1E distribution system from the offsite power system. In addition, the degraded voltage relay logic should appropriately function during the occurrence of an SIAS followed by a degraded voltage condition. ii. The second time delay should be limited to prevent damage to the permanently connected Class 1E loads. Following this delay, if the operator has failed to restore adequate voltages, the Class 1E distribution system should be automatically separated from the offsite power system. The bases and justification for such an action must be provided in support of the actual delay chosen. BTP 8-6-3 Revision 3 - March 2007 c. The voltage sensors should be designed to satisfy the following applicable requirements derived from IEEE Std. 279 and/or IEEE Std. 603, as endorsed by RG 1.153: i. Class 1E equipment should be used and should be physically located at and electrically connected to the Class 1E switchgear. ii. An independent scheme should be provided for each division of the Class 1E power system. iii. The undervoltage protection should include coincidence logic on a per bus basis to preclude spurious trips of the offsite power source. iv. The voltage sensors should automatically initiate the disconnection of offsite power sources whenever the voltage setpoint and time delay limits (cited in item 1.b.2 above) have been exceeded. v. Capability for test and calibration during