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On August 6, 2005, Units 1 and 2 were shut … On August 6, 2005, Units 1 and 2 were shutdown due to operability concerns potentially affecting the site's four Emergency Diesel Generators (EDGs). Unit 1 entered Mode 3 at 0531 hours and Unit 2 entered Mode 3 at 0446 hours. The EDG operability was questioned due to concerns that the setpoint for the installed EDG differential overcurrent protective devices (i.e., 87DP relays) was not appropriate.</br></br>Subsequently, it was determined that the setpoint for the 87DP relays, while not optimal, did not result in the EDGs being inoperable. As such, reporting of this condition is considered voluntary.</br></br>The root cause of this event is replacement of the EDG 87DP differential overcurrent relays, in 1982, without adequate confirmation that the trip setting of the new model was appropriate. This reduced the margin between the 87DP relay trip setpoint and the normal operating current, thereby reducing the EDGs' tolerance to electrical disturbances.</br></br>The existing 87DP relays were replaced with new solid state relays with increased margin to the operating current.increased margin to the operating current. +
On August 6, 2005, Units 1 and 2 were shut … On August 6, 2005, Units 1 and 2 were shutdown due to operability concerns potentially affecting the site's four Emergency Diesel Generators (EDGs). Unit 1 entered Mode 3 at 0531 hours and Unit 2 entered Mode 3 at 0446 hours. The EDG operability was questioned due to concerns that the setpoint for the installed EDG differential overcurrent protective devices (i.e., 87DP relays) was not appropriate.</br></br>Subsequently, it was determined that the setpoint for the 87DP relays, while not optimal, did not result in the EDGs being inoperable. As such, reporting of this condition is considered voluntary.</br></br>The root cause of this event is replacement of the EDG 87DP differential overcurrent relays, in 1982, without adequate confirmation that the trip setting of the new model was appropriate. This reduced the margin between the 87DP relay trip setpoint and the normal operating current, thereby reducing the EDGs' tolerance to electrical disturbances.</br></br>The existing 87DP relays were replaced with new solid state relays with increased margin to the operating current.increased margin to the operating current. +
Has query"Has query" is a predefined property that represents meta information (in form of a <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Subobject">subobject</a>) about individual queries and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
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6 +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
05:20:40, 1 December 2017 +
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