The New Age of Ventilated Dry-Type Transformers

In this "Cut the Copper" blog, manufacturers use air as a transformer coolant after their attempts to replace Askarel fluids met with little to no success.

04/27/2012


After enduring all of the pain and tremendous costs associated with replacing, rehabilitating, retro-filling and remediating nasty liquid-filled transformers, the electrical industry finally said, more or less in unison, “That’s enough! I’m not going to go through this anguish one more time! No more liquid transformers in my plants ever again. The EPA will never outlaw AIR as a transformer coolant, so from now on, my indoor transformers will be air-cooled.”

 

Manufacturers like GE and Westinghouse, again, led the charge and developed new dry-type substation transformer designs. The electrical industry adopted these quickly, and dozens of other smaller manufacturers entered the transformer business with new ventilated dry-type transformer designs.

 

Dry-type secondary substation transformers. Courtesy: ABB - T&DIn general, the new dry-types worked well in service, although early adopters immediately complained about how loudly they operated compared to the liquid units they replaced, and how much heat they generated when loaded. The most prevalent early designs used 220 C winding insulation and an allowable winding temperature rise of 150 C over a 40 C ambient. That says that the windings themselves could be operating in completely normal service at temperatures nearly twice the boiling point of water, so it’s no wonder that they felt “warm” (can you spell “i2R winding losses”?)

 

Later, next generation improvements included things like Vacuum-Pressure Impregnation (VPI) process, that greatly improved uniform quality of the insulation systems, and then lower temperature rise construction (115 C and 80 C ratings), that greatly improved efficiency and also extended useful operating life. 

 

In general, life was good, again, with many tens of thousands of dry-type transformer installations now in service.



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Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
Boiler basics; 2017 Product of the Year winners; Manufacturing facilities Q&A; Building integration; Piping and pumping systems
2017 MEP Giants; Mergers and acquisitions report; ASHRAE 62.1; LEED v4 updates and tips; Understanding overcurrent protection
Integrating electrical and HVAC for energy efficiency; Mixed-use buildings; ASHRAE 90.4; Wireless fire alarms assessment and challenges
Power system design for high-performance buildings; mitigating arc flash hazards
Transformers; Electrical system design; Selecting and sizing transformers; Grounded and ungrounded system design, Paralleling generator systems
Commissioning electrical systems; Designing emergency and standby generator systems; VFDs in high-performance buildings
As brand protection manager for Eaton’s Electrical Sector, Tom Grace oversees counterfeit awareness...
Amara Rozgus is chief editor and content manager of Consulting-Specifier Engineer magazine.
IEEE power industry experts bring their combined experience in the electrical power industry...
Michael Heinsdorf, P.E., LEED AP, CDT is an Engineering Specification Writer at ARCOM MasterSpec.
Automation Engineer; Wood Group
System Integrator; Cross Integrated Systems Group
Fire & Life Safety Engineer; Technip USA Inc.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
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