Maintenance strategy

Maintaining the high‑voltage grid is one of TenneT’s most important duties. Proper maintenance minimises the risk of disruptions that would have unacceptable consequences for the security of supply, the safety of our staff, the surrounding area and the environment as a whole.

Changing views

The various parties involved with TenneT demand that we do our job properly and become more aware of the costs. Over the years our views on maintenance have changed. We now know better what we should and should not do to keep our grid in good condition. We are also more aware of how we can keep our maintenance affordable without taking irresponsible risks. 

In line with our latest views, TenneT now: 

• performs fewer inspections;
• in general, conducts less preventive maintenance (but more where necessary); and
• replaces equipment if this is the most efficient solution.   

Fewer inspections

Preventive maintenance is intended to prevent disruptions from happening. One way TenneT tries to achieve this is by carrying out inspections. During these inspections, a member of the TenneT staff will investigate whether anything is wrong. From experience, we now know that many risks are not visible, and that the visible components are not always the critical parts of our network. Therefore, the number of inspections carried out by TenneT has dropped. 

Changing maintenance methods

It is no exaggeration to say that our high‑voltage grid is highly reliable. This is thanks to the ring‑shaped structure and the dual nature of our high‑voltage grid. If part our of grid fails, another part will take over the transmission of electricity. As a result, disruptions not always need to be prevented. 

Because of the high reliability of our network, we are adopting a more critical approach to standard periodic servicing. For example, it is no longer necessary to test a substation once every four years, ‘just to be sure’. In our experience, more specific maintenance activities (focusing on components that may lead to a critical disruption) make a better contribution to a properly functioning grid. At some sites we now perform less maintenance activities, therefore, while at others we perform more.

Replacement

A large part of the high‑voltage grid dates from the 1960s and is nearing the end of its expected useful life, i.e. the moment when repairs will no longer be possible and the equipment must be replaced. We intend to act upon this once necessary, without investing too early and causing needless expenses for society. Therefore, we are keeping an extra close eye on our older equipment. 

In addition, we look for trends in faults, so that we can anticipate major problems and prevent them. In case of major disruptions, we investigate whether replacement is a better option than repairing the fault. Sometimes repairs are so expensive or new equipment is so much better that replacement makes more sense.