High-standard electricity

The quality of electricity is made up of the reliability of distribution and the quality of voltage.   The fundamental factors behind the top-class energy security in Helsinki are the loop structure of the electricity network and the high level of cabling of the network.

More than 90% of the electricity network is cabled, which essentially reduces the number of supply interruptions caused by weather factors. Owing to the loop structure of the electricity network, electricity supply to every substation and every distribution substation can take place through at least two routes.

The three-level electricity network of Helsinki

  • In Helsinki, electricity is transmitted from power plants to consumers through a three-level network system. Different voltages levels have been used in order to minimise transmission losses and to ensure as cost-efficient power network operation as possible. 

  • The regional 110 kV high-voltage network is a transmission network which connects the power plants to the substations in the city and the city’s electricity network to the national grid.  

  • With the medium-voltage network, electricity is transmitted from substations to distribution substations, which feed the electricity further to the low-voltage network. The voltage level of the medium-voltage network is 10 kV in the city centre and 20 kV in the suburbs.

  • With the low-voltage network, electricity is transmitted to properties through electricity cabinets. The majority of the properties in Helsinki receive their electricity from the low-voltage (0.4 kV) network.

Sähkön jakelu

1. In a power plant, energy is converted into electric energy and kinetic energy.

2. Raising the voltage to a transmission-level voltage.

3. Operating connections, automatic separation of faulty parts from the electricity network and network quantity measurements are carried out at the switching substations.

4. 110 kV transmission lines.

5. In substations, the 110-kV transmission voltage is converted into distribution high voltage, which is 10 kV in Helsinki city centre and 20 kV in the suburbs.

6. With medium-voltage lines, electricity is transmitted from substations to distribution substations.

7. In distribution substations, the distribution high voltage is converted into low voltage.

8. Electricity is transmitted from distribution substations to places of consumption through low-voltage lines.