Streaming electrification measurements in a 1/4-scale transformer model

Citation
Ma. Brubaker et al., Streaming electrification measurements in a 1/4-scale transformer model, IEEE POW D, 14(3), 1999, pp. 978-985
Citations number
11
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
IEEE TRANSACTIONS ON POWER DELIVERY
ISSN journal
08858977 → ACNP
Volume
14
Issue
3
Year of publication
1999
Pages
978 - 985
Database
ISI
SICI code
0885-8977(199907)14:3<978:SEMIA1>2.0.ZU;2-Z
Abstract
Streaming electrification occurs in large power transformers when charge se paration takes place at the oil/cellulose interface as the oil is circulate d for cooling and can cause catastrophic failures. This study was performed with practical emphasis to examine the impact of cooling loop orientation and operation in the transformer lower plenum upon the electrification phen omenon. A simplified 1/4-scale shell-form transformer insulation structure was designed and fabricated for testing in an appropriately scaled tank com plete with six individual cooling loops. Discrete electrodes along the oil flow path facilitated mapping of the internal streaming current distributio ns as a function of various operating conditions. The streaming current mag nitudes and spatial distributions were found to vary with pump configuratio n, temperature and moisture. Furthermore, certain pumping arrangements whic h provided interfering transverse flows were shown to reduce local streamin g electrification.