Report defends HECO
The company's quake response was deemed in the public interest
Gradually restoring power on Oahu following the Oct. 15 earthquake was reasonable and in the public interest, according to a Hawaiian Electric Co. report submitted to the state Public Utilities Commission yesterday.
Idaho-based consultant Power Engineers Inc. prepared the report for HECO as part of a PUC investigation into the power outages on Oahu, Maui and the Big Island. The reports of HECO's sister Hawaiian Electric Industries subsidiaries Maui Electric Co. and Hawaii Electric Light Co. are due to the PUC by March 30.
THE OCT. 15 OUTAGE
7:08:23: First earthquake tremor reaches Oahu.
7:08:30: Shaking causes alarms at Kahe 3-4 and Kahe 5-6 control rooms.
7:08:58: Control operator shuts down Kahe 3 (Kahe 4 was already out of service for overhaul). Kahe 5-6 increases output to make up the difference.
7:09:08: Control operator turns off Honolulu 8.
7:11:00: Kahe 5 power output begins to drop, shuts down at 7:12:43.
7:11:50: System begins cutting off customers.
7:13:45: Kahe 6 output begins to drop. Operator initiates shutdown.
7:14:03: Remaining generating units shut down.
7:27:20: Islandwide blackout.
Source: Hawaiian Electric Company
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It took HECO more than 18 hours to restore electricity to all but 2,200 of its 291,000 customers following the magnitude-6.7 earthquake -- and a second magnitude-6.0 that struck a few minutes later -- off the Big Island.
The remaining customers had their power restored after they awoke the next morning, found that they still had no power and called the utility.
The HECO report echoes statements company officials have made to the PUC and public that a gradual restoration was necessary to prevent extensive damage to the system, and that it was the earthquake, not the shutting down of two units by operators, that caused the outage.
The earthquake triggered mercury-based switches on Kahe 5 and Kahe 6, HECO's two largest generating units, the report said. The switches cut off hydraulic fluid to the systems that control steam flow to the turbines and prevented the pumps from restarting to maintain the required hydraulic pressure.
Operators at Kahe 5 and Kahe 6 were too busy with a multitude of other alarms to be able to check the hydraulic fluid levels, determine the low-fluid alarm was false and manually turn off the switches within the three- to six-minute time window to prevent the two units from shutting down, the report said.
The shutdown of Kahe 5 and Kahe 6 started a series of events that led to the eventual shutdown of the entire grid, according to the report.
The report said the earthquake likely shook the mercury in the switches, causing them to falsely read low hydraulic fluid levels. HECO has replaced the mercury-based switches with ones that do not use liquid, said Jose Dizon, HECO spokesman.
The operators of Kahe 3 and Honolulu 8 did shut down the two generating units prior to Kahe 5 and Kahe 6 going down, according to the report, but the system continued to operate because there was enough capacity to make up the difference.
The operators shut down their units because they thought the shaking they were experiencing was due to turbine malfunction, the report said.
The public can read the entire 90-page report at HECO's downtown offices at 900 Richards St., at the Hawaii State Library at 478 S. King St. and at the PUC offices at 465 S. King St. A copy of the report's executive summary is available online at www.heco.com.
HECO also submitted a review of its communications to the media and the public during the outage, which it said was hampered by congested telephone networks, poor cellular telephone reception, and loss of cellular and most land-line telephone service to its Ward Avenue facility.
