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Atlas tips: Staying on top of corona incidents this summer

These past few months, the news has been filled with unfortunate stories of corona discharge incidents in heavily industrialized areas of the U.S. As we enter summer months which is when corona is the most active, especially in hot and highly humid areas, this article explains what corona is, its dangers, how to best detect it, and other tips on how to prevent potentially hazardous situations that could lead to unnecessary power outages affecting surrounding plants and neighborhoods.

What is corona?

Most people understand infrared which shows heat / resistance problems. It is readily found with thermal imaging (IR) and when the resistance gets too large, it trips a circuit protector and shuts down the system. Corona is dfferent – it is a voltage / grounding problem that does not show heat. Corona keeps growing until it finds a path to ground and then explodes. The most common assumption is that corona / partial discharge will go away once it is cleaned, either manually or by rain. The problem is that once corona starts, it begins to erode and corrode insulators which further exacerbates the problem and perpetuates the corona effect.

Many production and power plants use infrared (IR) to help identify problems in their substations, power lines, and high lines (transmission and distribution systems), often assuming that IR will detect all problems. IR will indeed help visualize and quantify resistance problems which will lead to heat build-up that can be detected by IR, but corona / partial discharge is only visible in the ultraviolet spectrum (UV) of light. IR will not show corona problems as illustrated by the two comparative pictures below.

What are the potential dangers of corona?

If corona is not detected early enough, or residual corona build-up on equipment in a substation is not washed away by rain in a timely fashion, it will lead to an equipment failure and a power outage that can seriously affect neighboring facilities such as refineries or pumping stations. For these industrial sites, it not only means expensive lost production and damaged equipment, but potentially major losses and release of toxic fumes into t he local environment which could be subject to an EPA fine and cause an emergency public health situation, with local people having to be hospitalized.

How can corona be efficiently detected?

Today’s highly specialized corona cameras offer a superior way of detecting partial discharge and arcing of electrical assets early. As partial discharge is not visible with thermal imaging technologies, this type of problem goes largely undetected until a failure occurs. Bi-spectral UV imaging allows for daytime inspection of key degradation and damage indicators on electrical utility components, including ceramic and non-ceramic insulators, terminators, or metal caps, as well as locating audio noise. This top-of-the-line technology can be used in all weather conditions. Specialized lensing and zoom capabilities allow inspection of assets from distances near or far. Bi-spectral imaging accurately gives the exact location of the UV event.

Corona cameras can be used at substations and distribution points, on transmission lines, and in medium- and highvoltage switchgear. Users can uncover early stage defects before destruction occurs to assist in developing efficient PdM planning and repairs. Locating and repairing sources of corona will create fewer opportunities for outages and interruptions, and uncover sources of noise and interference to TV and radio transmissions. Industrial-strength corona inspection cameras come with software which makes analyzing, storing, and reporting a straight-forward operation. Reports include bi-spectral over laid high resolution images and video, precision GPS-assisted locating of all sources of corona, and corona strength count.

Atlas corona prevention tips

• Corona situations require immediate attention: Corona is a hazard that is time-sensitive and needs to be dealt with right away. Proximity of response to corona problems is a serious consideration when hiring an emergency response team. Make sure to check the track record of the company you hire in terms of immediate staff and equipment mobilization.
• Operating corona equipment requires expert staff: Today’s corona detection technology is highly specialized, so hiring the right manpower with deep user expertise is essential to ensure not just the specific location of corona, but also the quantification of the problem. Ask your provider for the credentials of their UViographers to ensure you hire the right team.
• Corona prevention starts with regular corona inspections: Some sites inspected over periods of 12+ hours have found over 40 separate reportable corona incidents, hence the importance of scheduling regular inspections. For peace of mind, conduct two corona site inspections a year, one of which preferably during peak summer season.