Experience with Corona/Blackout Tests on Fully Assembled Stator Windings
Year: 2026
Type: conference-paper
Abstract: In recent years, Manitoba Hydro has begun performing corona/blackout tests on the stator windings of rotating machines to complement existing electrical tests that have been standard practice in the utility for decades. This paper provides an overview of the corona/blackout test, including its benefits and limitations. The paper also discusses results from two corona/blackout tests performed by Manitoba Hydro. Tests on a new winding revealed corona discharge between air gap bars and the winding's intermediate bracing ring, while tests on a 30-yearold winding showed discharges in the slot exit region due to degradation of the bars' stress control coatings. The issues discovered during the corona/blackout test were not found with typical insulation tests performed by the utility (including partial discharge). Based on our experience, this test has proven to be a useful acceptance test for new windings, and a practical diagnostic test for service-aged windings.
Authors: Mike Partyka, Tyler Black
Institution: Manitoba Hydro
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7202364572