- Author
-
Lin, W. H.
- Title
- Analysis of Fire Detection and Suppression Systems for Outdoor Oil-Filled Transformers.
- Coporate
- Worcester Polytechnic Inst., MA
- Report
-
Thesis
May 1991
220 p.
- Keywords
-
transformers
|
fire detection
|
fire suppression
|
pool fires
|
mathematical models
|
heat transfer
|
detector response
|
water sprays
|
spray nozzles
|
application rate
- Abstract
- An overview of the basic design, construction, electric and fire protection requirements for outdoor oil-filled transformers is presented in the first part of this thesis. Transformer internal arcing causes and consequences leading to various fire scenarios are also discussed. Pool fire heat release rates and flame heights are also analyzed as a function of pool size and wind speed. Small scale experiments involving 0.26 meter diameter pool fires, with 0.1 m diameter simulated transformer and with 1.5 cm diameter gravel stones around the transformer have been conducted. The gravel stones around the mock transformer reduce the flame height by 19% and the heat release rate by 32% compared to the data with no gravel present. Fires were extinguished when the liquid level decreased to the gravel level. A mathematical model for estimating thermal detector response time has been developed for outdoor transformers. It is found that most detectors located within the flame will respond within a few seconds in a large transformer (60 MVA) fire, depending upon the detector thermal capacity, mdcd/Ad, where md is the detector mass, Cd is its specific heat, and Ad is its surface area. Detectors located in the fire plume should respond in 1.0-5.6 minutes depending on the fire size if mdCd/Ad= 20 KJ/m²K.