POINT BEACH NRC NOTIFICATION OF UNUSUAL EVENT: LOSS OF OFFSITE POWER TO ESSENTIAL BUSES FOR GREATER THAN 15 MINUTES

At 1132 CST on 2/6/13, Point Beach Unit 1 experienced a loss of all offsite power due to the loss of 1X-03 High Voltage Station Aux Transformer. The high side circuit switcher opened. However, the 1X-03 transformer did not lock out resulting in G-01 and G-03 Emergency Diesels energizing the 1A-05 and 1A-06 4160 VAC busses (safety related)."

The cause of the loss of offsite power is being investigated. In order to exit the event, the plant requires either 345 kV power to be restored or cross-tie plant power between the units. If cross-tied, Technical Specifications require the gas turbine to be placed on the cross-tie within 24 hours. The plant remained at 100% power and there was no effect on Unit 2.
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