Information about power cuts

What causes power cuts?

Power cuts are most commonly caused by weather conditions such as storms, lightning and heavy snow loads accumulating on trees. Excavation work, equipment damage and small animals can also cause interruptions to electricity supply. In some cases, electricity must be switched off as part of planned maintenance, repair or improvement work on the electricity network.

A power cut is not always caused by a fault in the electricity distribution network. It may also result from, for example, a blown fuse in the customer’s property or a fault in an electrical appliance.

What are short power cuts, or momentary interruptions?

Momentary interruptions are brief power cuts caused by the protection systems of the medium-voltage network. They often prevent longer power cuts from occurring. When a fault is detected, the network protection system automatically interrupts the electricity supply and attempts to restore power after a short period. The system makes its first reconnection attempt in less than a second and, if the fault persists, tries again a few minutes later. Several brief interruptions may occur while the fault is being identified.

Momentary interruptions are most commonly caused by large migratory birds during spring and autumn, lightning, branches blown by the wind and, in winter, heavy snow loads. Thanks to the automatic protection system, longer power cuts can often be avoided, as most disturbances are cleared during its operation.

How does Caruna reduce the duration of power cuts?

We aim to ensure the most reliable electricity supply possible, although this is not always achievable.

We reduce faults that cause prolonged power cuts through measures such as network automation. When the automation system detects a fault in the electricity network, it performs what is known as an automatic reconnection. During this process, the electricity supply is interrupted briefly and then restored. The interruption typically lasts from less than a second to a few minutes.

We also reduce the duration and extent of power cuts by using remotely controlled devices installed in the network. Remote control makes it possible to isolate the fault area and restore electricity to as many customers as possible. Customers outside the isolated fault area can have their electricity restored once an electrician has repaired the fault.

The reliability of electricity supply, including the number and duration of power cuts, is defined in industry recommendations. More information is available on the website of Finnish Energy Industries.