January 2014

Dolan Technology Center hosts annual corona activity workshop

Daytime corona camera technology was the focus of a workshop held at the DTC. Sponsored by the Daytime Discharge Inspection Interest Group (DDIIG) of the Electric Power Research Institute (EPRI), the annual event allows utility professionals to discuss various aspects of corona activity. Read more at Dolan Technology Center.

Daytime corona camera technology was the focus of a recent workshop held at Dolan Technology Center (DTC). Sponsored by the Daytime Discharge Inspection Interest Group (DDIIG) of the Electric Power Research Institute (EPRI), the annual event allows utility professionals to discuss various aspects of corona activity.

Dave Klinect, DTC senior engineering technologist and vice chairman of the DDIIG, described corona as the result of decreasing insulating properties of air on power lines or at substations as voltage increases. Corona effects can include audible noise and radio interference signals.

Although corona can be viewed at night, Klinect said daytime viewing is preferred. It has to be really dark to effectively see corona and given the remote locations of some transmission towers, doing so at night can be dangerous. "Daytime corona cameras allow us to do more testing and do it with greater safety," he said.

Watch video of corona activity.

The video shows corona on an in-service 138-kV polymer insulator during light rain captured with a daytime corona camera.

Damage to this insulator can be detected with a daytime corona camera. Photo Dave Klinect.

The two-day event included a tour of the DTC, hands-on product demonstration of daytime cameras and roundtable discussions. "In preparation for the workshop, several group members viewed a known corona source and tested six cameras to compare how they responded to this source." Klinect said.

Attendees from across the United States and from other nations came together to share ideas and to help each other learn. A representative from Namibia attended his first workshop this year.

"We are a young (electric) system. EPRI is one of the first groups I joined in order to familiarize myself with the industry and see what ground the other guys have covered," said Ronald Kubas, a transmission engineer with NamPower LTD.

Mike Kokosz is an engineer for CenterPoint Energy. "I operate the corona camera. This (workshop) gives me training and insight in how to use the camera and how to determine when there is an issue and when I need to replace a conductor."

DTC personnel use corona cameras for a wide variety of in-house testing, such as monitoring the corona activity during an aerial lift electrical certification test or monitoring insulator corona activity during high voltage testing of those items. DTC personnel also assist Generation and Transmission by performing corona inspections at transmission facilities or inspecting generator step-up transformers at power plants, looking for indications of defects on porcelain bushings and arresters.

"Your lab is great," said Alabama Power's Greg Coffey, a transmission analyst. "We don't have anything like that. So to come out to have different scenarios for us to see and how the cameras react in real time is very beneficial."

It's always good to get together with other members to see how they are doing things and the things they're running into—and hopefully apply what we learn here to our job," Coffey added.