Skip to content

Infrastructure management

Regular maintenance of the infrastructure helps to minimise the risk of power failures, damage to the environment and safety incidents.

Infrastructure management

Security of supply

As the manager of the Dutch high-voltage grid and a large part of the German high-voltage grid, one of our main tasks is to make sure the infrastructure – the substations, power lines and cables – is always in good working order. 

Regular maintenance of the infrastructure helps to minimise the risk of power failures, damage to the environment and safety incidents. We do this in the best possible way and at an acceptable cost. After all, our customers expect a reliable energy supply at a reasonable price. We therefore pay considerable attention to new maintenance methods and techniques so that we are continually improving.

Preventive

Our high-voltage transmission grid spans around 23,000 kilometers and high voltage substations. We take preventive measures to ensure it always functions well: we carry out regular inspections and maintenance work. If there is a fault, we repair it. Such faults, however, rarely lead to power outages in our network.

Substations

The substations are equipped with transformers. These increase or decrease the voltage so we can connect 380 kV power lines to 220 kV lines and to the regional grid operators (50 kV and below). Transformers have a long lifespan and can work for decades. We therefore inspect them regularly, along with the other equipment located in and around the transformer. 

Power lines and masts

Power lines and pylons are relatively low maintenance. They last for decades, with pylons requiring little more than an occasional new coat of paint. We inspect the connections every 8 to 10 years and randomly carry out top-to-toe mast inspections. Parts of the mast that do sometimes need replacing are the insulator strings, which separate the live power lines from the pylons, and the spacers, which keep the lines far enough away from each other.  

Every year, we carry out aerial inspections by helicopter of the conductors, the suspension and the buildings near the power lines. We also maintain the trees and plants around the substations, pylons and high-voltage lines so they don’t obstruct the energy supply. 

Maintenance strategy

The upkeep of the high voltage network is one of TenneT’s most important tasks. It reduces the risk of disruptions and ensures the security of the electricity supply.

Inspections and preventive maintenance

The upkeep of the high voltage network is one of TenneT’s most important tasks. It reduces the risk of disruptions and ensures the security of the electricity supply. Our experience over the years has shown what we should do to keep our network in a good condition and how we can keep the maintenance costs affordable, without taking irresponsible risks.

This includes: 

  • Carrying out fewer but targeted inspections
  • Doing less preventive maintenance work in general, but more where necessary
  • Replacing equipment if that is the most efficient option

Fewer, but more focused inspections and replacements

Inspections help us to spot potential problems before failures occur. However, the equipment parts that could potentially be at risk are not always visible. That’s why we target our inspections, which also means we don’t have to conduct as many.

Much of the high-voltage network was built in the 1960s and is approaching the end of its expected technical life. We therefore keep a close eye on the older equipment and replace it as necessary.

In the event of a large disruption, we investigate whether it is better to replace the faulty equipment or repair it. Sometimes repairs can be more expensive or the new equipment is superior. We also look out for trends in faults so that we can take action to prevent larger problems.

Scheduled maintenance

We only carry out maintenance work when the availability of the transmission grid permits this. We therefore have a coordinated plan for carrying out preventive maintenance work.

Redundancy and ring structure

The high-voltage transmission grid is designed so that parts of the network can be switched off for scheduled maintenance without impacting the electricity supply for our users. Certain grid components are serviced in this way every week .

Our transmission system has redundancy built in. This means the critical components are duplicated: there are two circuits for each high-voltage connection and extra transformers in the high-voltage substations. This redundancy allows us to continue transmitting electricity while we are doing maintenance work. 

In addition, the grid is structured in a ring shape. If there is a disruption somewhere, we can reroute the electricity along an alternative path. 

Planning maintenance

We only carry out maintenance work when the availability of the transmission grid permits this. We therefore have a coordinated plan for carrying out preventive maintenance work, so we are sure the system can also cope with any unscheduled disruptions during the planned service outages. We determine beforehand whether it is safe to proceed with the scheduled maintenance. 

Work safety

The safety of our employees during maintenance work is paramount. That is why it takes several people to shut down parts of the high-voltage grid and everyone involved has to follow strict procedures and wear protective clothing.

Contacts

Susan Smit from TenneT CCC

General Contact

General Contact of TenneT Netherlands

Monday to Friday from 8:30 a.m. to 5:00 p.m.