Subject:Rush Island Power Plant - Transformer Fire
Date
of Email report:Fri 09/03/2012
Report Detail:
TRANSFORMER FIRE (below is an excerpt from an announcement)
Ameren experienced a transformer fire at one of its power plants on January 27, 2012 at approximately 5:27 p.m. The fire was at our Rush Island Power Plant which is located approximately 50 miles southeast of St. Louis, MO. The plant has 2 – 640 MW rated units. Each unit has a set of three (3) transformers (GSU, Unit, and Starting Transformer) and are separated from the other unit’s transformer group by an 18-ft. high fire wall, constructed of pre-cast concrete panels inserted in slotted pilasters.
The transformer involved was a “unit” transformer on Generating Unit 2. The transformer was manufactured by Wagner Transformer, was installed in 1977, rated at 45000 KVA. The transformer tank contains 3,650 gallons of mineral oil.
At the time of the incident Unit 1 was at 600 MW and Unit 2 was at approximately 400 MW. At approximately 5:27 p.m., an employee was in the area of the 2A and 2B bus and reported seeing a flash in the upper cable tray (Unit Bus 2B). An outside employee similarly reported seeing fire at the Unit 2 Unit Transformer. Generator breakers opened, probably from differential current (low- side fault) to take Unit 2 off-line.
A fire ensued from the Unit 2 Unit Transformer, when the tank ruptured at the upper welded seam corner. Mineral oil was spewed in a diagonal upper direction; Smoke from the fire created an arc between phases of the Unit 1 Generator Transformer; subsequently, Unit 1 tripped offline. Station Power remained supplied through starting transformers on the respective units.
Water for fire protection is from two 1500 gpm, 165 psi, electric motor drive fire pumps, taking suction from a 250,000 gallon treated water tank. A 1250 gpm, 150 psi diesel drive fire pump, automatic starting, is also available. Four deluge fire systems tripped automatically, one system on each of the “generating” transformers, and one system on each “unit” transformer. The deluge systems quickly controlled the fire. Ameren has starting installing water curtains above each transformer on our deluge system upgrade program, to provide exposure protection for the turbine building. The water curtains minimized damage to the plant building. Damage to the plant occurred most where there was no water curtain coverage. After the fire it was determined that the four deluge systems activating simultaneously used approximately 243,000 gallons of water in 40 minutes.
The Plant’s Emergency Response Team is trained to the “interior structural level.” The ER Team consisting of 4 supervisors and 5 plant operating engineers responded and put out fires on the roof of the turbine building and around the transformers. Three volunteer fire departments responded to the site approximately 20 minutes into the event, but the fire was essentially out.
What makes this event interesting is our security cameras caught this event from three viewpoints. The first angle is from a camera at the main entrance that looks across the switchyard directly at the transformer bay. You can see the initial fire ball and quick knockdown by the deluge system. The second camera was pointed toward our caisson, but you can see the flash of the release, security then turns that camera toward the plant and you can see the fire extension to the roof of the turbine building. The third camera is looking toward the entrance of the plant, you see the flash of the fireball and again security turns the camera toward the roof of the turbine building.
