Hawaiian Electric Co. officials say the unexpected shutdown of Oahu’s largest generator prompted the utility to launch emergency outages across the island Wednesday. 

The 180-megawatt generator at Campbell Industrial Park shut down around 11:23 a.m., leading to outages in Waialua, Kahuku, Waihee, Kaneohe, the Kapiolani area, downtown Honolulu, Waiakamilo, Moanalua, Halawa, Moanalua, and Waipahu, HECO officials said. The plant is operated by the independent power producer AES, according to HECO. 

Power to most affected customers was restored shortly before 12 p.m., and all the affected areas should have power restored, HECO spokesman Darren Pai said before 1 p.m. 

“The targeted emergency outages were necessary to avoid a more widespread outage or damage to the electric system from an imbalance of too much demand versus too little available generation,” a HECO news release said. Company officials said they would be working with AES to investigate the cause of the plant shutdown. 

City officials first announced the outages late Wednesday morning. “Turn off and disconnect non-essential equipment and appliances,” a city advisory said. “Use battery operated radio to get news and information. Keep refrigerator and freezer closed to conserve cold.”

Hawaiian Telcom also experienced problems with their phone system Wednesday morning. 

Su Shin, Hawaiian Telcom spokeswoman, said the problem was with phone service provided through an Internet connection — known as “voice over Internet protocol,” or VOIP — and began at 10:30 a.m., mainly on Oahu. About 800 business and residential customers were affected, and some of Hawaiian Telcom’s Internet and TV service was also interrupted.

The company began to reroute its phone and data traffic and some service was restored by 11:15 a.m., she said. Any customers still experiencing problems can call 643-6111.

The Honolulu Police Department said they were not affected by the phone service problem.