Enhancing fire safety at Hydro plants with dry transformers
- Harza Engineering Company, Chicago, IL (United States)
Hydroelectric plant owners and engineers can use dry-type transformers to reduce fire hazards in auxiliary power systems. The decision to replace a liquid-immersed transformer with a dry-type product has a price: higher unit cost and a need to be more vigilant in detailing transformer specifications. But, whether the change affects only one failed transformer or is part of a plant rehabilitation project, the benefits in safety can be worth it. Voltages on hydroelectric plant auxiliary power systems can range from a 20 kV medium-voltage system to the normal 480-208/120 V low-voltage system. Dry transformers typically are used in such systems to reduce the fire hazard present with liquid-filled transformers. For a hydro plant owner or engineer seeking alternatives to liquid-filled transformers, there are two main kinds of dry-type transformers to consider: vacuum pressure impregnated (VPI) and cast coil epoxy resin. VPI transformers normally are manufactured in sizes up to 6,000 kVA with primary voltage ratings up to 20 kV. Cast coil transformers can be made in sizes from 75 to 10,000 kVA, with primary voltage ratings up to 34,500 V. Although the same transformer theory applies to dry transformers as to liquid-filled units, the cooling medium, air, required different temperature rise ratings, dielectric tests, and construction techniques to ensure reliability. Consequently, the factory and field tests for dry units are established by a separate set of American National Standards Institute (ANSI)/Institute of Electrical and Electronics Engineers (IEEE) standards. Cast coil transformers have several important advantages over VPI units.
- OSTI ID:
- 6011157
- Journal Information:
- Hydro Review; (United States), Vol. 7:4; ISSN 0884-0385
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROELECTRIC POWER PLANTS
SAFETY
TRANSFORMERS
FIRE HAZARDS
FIRE RESISTANCE
COST BENEFIT ANALYSIS
COST ESTIMATION
ECONOMIC ANALYSIS
ECONOMICS
ELECTRICAL EQUIPMENT
EQUIPMENT
HAZARDS
POWER PLANTS
130800* - Hydro Energy- Health & Safety- (1990-)
130700 - Hydro Energy- Power-Conversion Systems