A large Southeastern utility company needed to replace the water coolers at an aging electric generating plant. Built in 1948, the
plant’s six identical Westinghouse Generator Step-Up power transformers were fully operational, with all active parts still in very good
condition. The twin water coolers attached to each unit, however, did not hold up as well. Over time, parts on the coolers had oxidized
and began leaking.
The onsite power generation station and the 90-MVA Moloney electric transformer, built in 1958, were installed halfway up the
mountain slopes. With continuous load growth, the transformer was operating well above the nameplate recommendations.
The single 5-hp oil pump and the three 1-hp fans on each of the four traditional oil coolers were not providing adequate
cooling. The onsite operations manager of the generation station told us, “The coolers were not cooling at all. They were
plugged or the fluid was passing through too quickly to cool.” Mountain States Transformers (MST), who maintained the
transformer, said “The coolers were fouled and the oil temperature was hitting the warning trips often.”
The coal fired generation plant has a 128MVA transformer rated to operate with a top oil temperature of 65°C. The cool-ers on the transformer had corroded and were leaking oil. The drip pan was continuously filling up and the oil level in the transformer would quickly drop to make the transformer non-operational. Due to the age and extent of the corrosion, the coolers were beyond the scope of repair and had to be replaced.
Nucor - Birmingham purchased a new 3 Phase Current Limiting Reactor for their Arc Furnace application. The existing
cooling unit supplied with this new reactor was a 250kW OFWF system that the OEM supplier (ABB) typically furnishes
with this model reactor. Trantech was asked to study this application for alternative cooling methods based on:
1. The ability to reduce extended downtime situations for maintaining the cooling system.
2. Lack of continuous or treated water supplies to the reactor.
3. Ability to maintain cooling capacities in situations of higher than rated usage of the reactor.