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Low frequency heating field dry-out of a 750 MVA 500 kV auto transformer

Abstract

This article reviewed the use of 750 MVA 500 kV autotransformers and low frequency heating using low frequency measurement. The main purpose of performing site dry-outs of power transformers is to reduce the moisture content in the cellulose. Moisture is a by-product of the aging process of the cellulose or occurs externally from the transformer through gaskets and leaks. Moisture deteriorates the electrical and mechanical properties of the transformer and can limit the allowed overload due to risk of water bubble formation. Following a recent investigation of the failed system autotransformer, Hydro One invested in a program of site drying its fleet of 500/230 kV autotransformers. This group of autotransformers is the backbone of the transmission network in Ontario. One of these units, a 750 MVA 500/230/28 kV three phase autotransformer, underwent a failure only hours after a sister unit at that station had been removed from service due to a high moisture alarm from an on-line monitor. The resulting investigation showed that moisture was a main contributing factor to the failure. It was concluded that although the number of confirmed measurements was limited, the low frequency heating method was superior to previously used methods. 1 tab., 2 figs.
Authors:
Figueroa, E; Kalicki, T; [1]  TeNyenhus, E [2] 
  1. Hydro One Networks Inc., Toronto, ON (Canada)
  2. ABB Inc., Brampton, ON (Canada). Transformer Remanufacturing and Engineering Services
Publication Date:
Jan 15, 2009
Product Type:
Journal Article
Resource Relation:
Journal Name: Electricity Today; Journal Volume: 21; Journal Issue: 1
Subject:
24 POWER TRANSMISSION AND DISTRIBUTION; TRANSFORMERS; POWER TRANSMISSION; MECHANICAL PROPERTIES; ELECTRICAL PROPERTIES; FAILURES; MOISTURE; FREQUENCY MEASUREMENT; CELLULOSE
OSTI ID:
21161819
Country of Origin:
Canada
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0843-7343; ELTDER; TRN: CA0904369
Submitting Site:
CANM
Size:
page(s) 8-10
Announcement Date:
May 28, 2009

Citation Formats

Figueroa, E, Kalicki, T, and TeNyenhus, E. Low frequency heating field dry-out of a 750 MVA 500 kV auto transformer. Canada: N. p., 2009. Web.
Figueroa, E, Kalicki, T, & TeNyenhus, E. Low frequency heating field dry-out of a 750 MVA 500 kV auto transformer. Canada.
Figueroa, E, Kalicki, T, and TeNyenhus, E. 2009. "Low frequency heating field dry-out of a 750 MVA 500 kV auto transformer." Canada.
@misc{etde_21161819,
title = {Low frequency heating field dry-out of a 750 MVA 500 kV auto transformer}
author = {Figueroa, E, Kalicki, T, and TeNyenhus, E}
abstractNote = {This article reviewed the use of 750 MVA 500 kV autotransformers and low frequency heating using low frequency measurement. The main purpose of performing site dry-outs of power transformers is to reduce the moisture content in the cellulose. Moisture is a by-product of the aging process of the cellulose or occurs externally from the transformer through gaskets and leaks. Moisture deteriorates the electrical and mechanical properties of the transformer and can limit the allowed overload due to risk of water bubble formation. Following a recent investigation of the failed system autotransformer, Hydro One invested in a program of site drying its fleet of 500/230 kV autotransformers. This group of autotransformers is the backbone of the transmission network in Ontario. One of these units, a 750 MVA 500/230/28 kV three phase autotransformer, underwent a failure only hours after a sister unit at that station had been removed from service due to a high moisture alarm from an on-line monitor. The resulting investigation showed that moisture was a main contributing factor to the failure. It was concluded that although the number of confirmed measurements was limited, the low frequency heating method was superior to previously used methods. 1 tab., 2 figs.}
journal = []
issue = {1}
volume = {21}
place = {Canada}
year = {2009}
month = {Jan}
}