What is Corona Loss in OHTL and Why It Matters

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What is Corona Loss in OHTL and Why It Matters

Corona Loss- the rate at which power is leaked out by corona discharge from high voltage OHTL (Over Head Transmission Lines). The issue of Corona Discharge is one that has plagued Power and Transmission companies since the start. Extra high voltage lines are often victims of Corona Discharge, significantly reducing their efficiency resulting in lost revenue and higher maintenance costs.

Note: Corona Discharge here and in this article is only related to the phenomenon of electric discharge through ionization of localized air. Not to be confused with COVID-19.
Corona Discharge is a systemic symptom of a higher issue. While on the surface it just seems like loss of power through ionization of air, the implications are more massive. In this article we explore how out of 5,262 towers we inspected 40% of them suffered from Corona Loss. Essentially, that's 40% of towers bleeding out revenue, and on top of that, the longer Corona discharges are allowed to be expelled the more damage it causes to equipment around it.

Other than just loss of power, which directly impacts revenue, corona discharge brings with it a host of other issues like:

1. Electric Power Transmission, where it causes,
  • Power Loss
  • Audible noise
  • Electromagnetic interference
  • Purple Glow
  • Ozone production
  • Insulation Damage
  • Distressing animals
2. Electrical components such as transformers, capacitors, electric motors and generators,
  • Damaged insulation leading to equipment failure
  • Elastomer items such as O-rings can suffer Ozone cracking
  • Vaporization of metal can cause plastic film capacitors to lose capacitance

Companies can combat corona discharge by increasing conductor size, increasing distance between conductors and using Corona Rings. But the main challenge is effectively identifying problem areas across hundreds of kilometres of power lines and towers. Additionally, they are invisible to the naked eye and can only be detected using specialized UV sensors.

Previously, only helicopters or ground teams using specialized equipment were the only option to conduct inspections. But they are highly inefficient and time-consuming- like we’ve already explored in our previous article on how we were able to increase inspection efficiency by 80% while inspecting OHTLs.

You could average a total of 3 towers inspected per day using the traditional methods, but that be sped up ten-fold to a staggering 30 towers inspected per day but introducing drones. To detect Corona Discharge, it’s a simple matter of swapping out the payload to one that has UV detecting capabilities.

Drone Inspections of OHTL towers are incredibly efficient and effective, giving you a more cost-effective alternative to ground teams or helicopters. Drones can also carry out multi-spectral inspections, giving you the option to capture data in RGB, UV or even Thermal to gain deeper insight into your power infrastructure and increase reliability.

40% of Towers Detected with Corona Discharge

In the southern regions of the Kingdom of Saudi Arabia, FEDS were contracted to inspect 5,262 towers by the Power & Utilities giant SEC (Saudi Electric Company). The towers roughly sprawled over a massive distance of 3,790 km, usually through difficult terrain and mountainous regions needed to be inspected. The traditional helicopter and ground team methods would be expensive and inefficient, so drones were selected as the tools to carry out inspection.

Using drones precise and high-resolution imagery were obtained of each tower, FEDS also used multi-sensor cameras to capture thermal and UV data. Using drones, the inspections proceeded at a rapid phase- at a rate of 30 towers per day. Compared to the three per day, this was a considerable increase in efficiency.

FEDS, being the only organization in the middle east to have specialized UV sensors compatible with drones, could scan the Power Infrastructure for any Corona Discharge issues swiftly. The results were a staggering 40% of the total towers suffered from Corona Loss. If left unchecked, the Corona discharge would cost the company millions in lost resources. Reports were then generated and relayed near real-time, enabling the company to plan and execute a quick and efficient maintenance drive.

If the inspections were to be carried out by helicopter or ground teams, the visibility afforded would be limited, leading to inaccurate inspection reports with several Corona Discharge issues going undetected and unreported. Additionally, inspecting all these towers would have roughly taken 1756 days to complete without drones. Throughout that time, the 2000 towers detected with Corona Loss would have continued to leak power, resulting in a lot of revenue lost.

FEDS using their UV sensors could quickly and effectively detect instances of Corona Discharge with a high level of accuracy. The data provided by the FEDS team enabled the SEC to mount an effective maintenance operation that significantly reduced Corona Loss and increase their overall inspection efficiency by 80%.

About the author

Niiveth Mani


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