The power increase on the other two lines caused
them to trip as well, blacking out the area that had just been
restored. A second restoration commenced quickly, bringing the
138-kV network back up by 12:55 a.m. on 15 August and the
46-kV network, with all customer load, by 1:35 a.m. A fault
location was identified from relay data, but a cause for the fault
was not found at the indicated location. The line was given a
derated capability when it was reclosed at 11:00 p.m. Because
of the limitations of the system caused by the derating, 40 MW
of load, served by four 46-kV lines, was manually shed between
7 a.m. and 9:30 a.m. on 15 August; the lines were restored when
a Whiting generator came back online.