Abstract: A preventive maintenance tapping technique includes noting a tap position of a load tap changer and noting a duration that the tap position has been held. The duration that the tap position has been held is compared to a threshold value, and the tap position is changed if the tap position has been held for longer than the threshold value. Similarly, a duty cycle monitoring technique for monitoring life of load tap changer contacts includes detecting an arcing event. Arcing surfaces involved in the arcing event are identified and the effects of the arcing event on the arcing surfaces are calculated. Estimates of the erosion on the arcing surfaces are updated, and the estimates are compared to a threshold value. A signal for maintenance is generated when the estimate exceeds the threshold value.
Type:
Grant
Filed:
May 31, 2005
Date of Patent:
January 27, 2009
Assignee:
Cooper Technologies Company
Inventors:
Fred J. Rapant, Richard J. Kaluzny, Donald A. Down, Augusto D. Hernandez, Jr., legal representative, Augusto D. Hernandez