40,000 km inspection to Estonia’s largest network operator

Elektrilevi's full scale grid analysis


Elektrilevi, being the largest distribution network operator in Estonia by covering staggering 93% of the country’s power line infrastructure, felt derailed and reluctant to their performance on asset management.

Despite being a large-scale publicly owned enteprise, Elektrilevi is well known by its competitive strive towards the future grid & digitisation. They lust to offer to society & consumers a high-quality experience by effectively developing their network systems and organizational procedures.

power line analysis drones uav artificial intelligence


The success story of Hepta has become known due to mix of unique skill-set and experience in the team:

  • 15+ years of experience in on-ground grid inspection
  • 7+ years of experience in helicopter grid inspection
  • 8+ years of experience in drone grid inspection
  • Including data scientists working with satellite data, software engineers deploying machine learning models, aerospace engineers having previously built manned helicopters

Aforementioned combination of unique skill-sets enabled us to approach Elektrilevi’s use case in an agile way.

Carrying the weight of analyzing the entire electricity network of Estonia, cannot be disrupted with novel solutions promtly and in full-scale from the next day.

The heavy responsibility was not to be taken lightly.

Read the full use case below. 

First 2 months of sUAV-testing eventuated with two times faster inspection results

Previous situation

Elektrilevi’s asset management procedures were mostly performed by in-house team of on-ground patrol and motorised vehicles. The usual pristine disadvantages of the conventional inspection created high level of impermanence within the organization:

  • Vast majority of the network area is in rural areas, unreachable to motorised vehicles
  • On-foot patrol is time-consuming, costing up to 7 years for a typical DSO to complete the full cycle.
  • On-foot patrol is highly inaccurate. Instead of state-of-the-art sensors, we rely on subjective view of an human eye
  • On-foot patrol is dangerous. Daily, line-men must embark perilous journeys to hazardous work-environments

Nevertheless, inspection provides us with actionable insights to the capital-intensive strategical assets. Having a complete and accurate overview of the assets’ conditions plays a crucial role in utility’s day-to-day decision-making.

Actionable insights provide direct input to network planning, maintenance, financial and procurement departments for the upcoming years, to keep the flow of electricity safe, constant at low-cost

Peckish to strive towards future grid and automated asset management, Elektrilevi started to look for alternatives. In 2018 they decided to announce a tender for the private sector, lurking for innovative alternatives to conventional power line analysis. The new concept depicted groundbreaking change:

  • Re-organized roles for the entire maintenance team
  • Full-scale end-to-end inspection delivery was now outsourced
  • Elektrilevi’s new position had become an intelligent-contractor

As may be expected, Hepta was ready to take prompt actions.

In the early 2018 Hepta signed two-out-of-two framework agreements, obtaining the trust by largest network operator of Estonia to deliver full-scale inspection & analysis to close-to 93% of the entire country’s network. 



Start with small steps

During the first 6-month kick-off period our team studied cautiously every detail of the Estonian network, by executing the inspection with precisely the same – conventional and inefficient on-ground methods. We learned, and we did not enforce any changes.

Our primary target was to obtain clear overview of customer’s procedures, enabling us to:

  • identify the core values & technical aspects, important to Elektrilevi
  • identify deficiencies within the existing procedures
  • pinpoint potential improvements without involving any risks

Slow but steady progress

At first, we trained our on-ground team with small off-the-shelf drones. Easy to handle, low-entrance in costs. First UAV missions were conducted on the middle voltage overhead lines, which from the airborne inspection perspective have significant risk-lowering advantages comparing to low voltage networks:

  • Lines are longer and straighter, including with less branches
  • Right of Way (danger zone) of the line corridor is wider and cleaner

First 2 months of sUAV-testing eventuated with two times faster inspection results!

Instead of typical 160 km per month, we reached to astonishing 320 km of analyzed grid, per one engineer.

As a “side bonus”, we started to receive frequent positive mentions from the customer, based on to the digital footprint which the high-definition close-up view of the UAV images successfully supplied.



Full execution

Having injected by the boost of confidence from the sudden success we replace sUAV’s with Hepta’s in-house built industrial drones, delivering BVLOS missions to hundreds of kilometers. 
As for the low voltage, we are currently following smilar cautious principles:

  • Implementation of the small UAV’s
  • Partially replacing sUAV’s with long-range drones

Software & analysis

Drones are just one side of the solution.

We deploy machine learning models to accelerate the analysis of image data. Our software works in deep synergy with trained grid-technicians. We leave our  customers with a fast, cost-efficient up-to-date overview of the mechanical defects along the line.

By the way – 100% accuracy guaranteed!

Elektrilevi's Asset Management today

  • 100% of middle voltage grid is inspected by automated UAVs
  • 30-50% low voltage grid is inspected by automated UAV’s. Rest of the grid with on-ground methods.
  • Machine learning is deployed to daily analysis procedures
  • PoC’s to acquire data from other sources have been initiated (land-board, satellite, etc)

Results & benefits

  • The inspection cycle has decreased from 7 years to 2,5 years!
  • Cost level, comparing to alternatives is 2 times lower
  • Accuracy. We find on average 11 more defects per line kilometer
  • Elektrilevi has attained a long-lasting digital footprint of the entire power line, including its critical defects & failures

Interested to read more? See Elektrilevi’s press release here.

"Hepta’s inspection solutions provide us with insights which dramatically help decreasing maintenance costs and reduce failures. By extending the lifespan of the assets we are able to avoid their replacement."
Rasmus Armas, Head of Asset Management, Elektrilevi

Contact us to learn more about digitizing infrastructures and conducting utility inspection with drones and AI

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