Medium voltage line goes through familiar rural village and continues for tens of kilometers in forest without any protection towards the last small village. Sensitive – especially fault sensitive. Fortunately there is a solution.
The rescuer has been found, Ensto Smartcloser, a clever recloser that is able to separate fault locations automatically from the network. This secures electricity distribution to villages in the beginning of the distribution line.
Ensto's recloser has already long experience around the world and now it is ready to take on Finland's exceptionally challenging conditions. Further development has been conducted together with network companies and technology suppliers such as Arcteq from Vaasa, Finland. This guarantees excellent performance in all circumstances.
The deliveries have started and Smarclosers are already in action. Regarding the most challenging conditions, two locations are exceptional – North-West Lapland with its weather variations and Northern Karelia with its vast forests.
Frost harm under control at Enontekiö
”During the summer it is hot and during the winter temperature might drop to -50C degrees at lowest. There is snow from October to May", describes planning engineer Johannes Rauhala from Enontekiön Sähkö.
”Nunnanen branch line, where the recloser was installed, is exceptionally sensitive to frost during the winter period. In the summer it is prone to thunder faults. With the recloser installation we want to eliminate the faults and constant reconnections that affect the customers in Peltovuoma and Vuontisjärvi villages."
According to Rauhala the protection is now more selective as the network can be cut to sections. Fault location can be isolated more precisely and faster than previously. This decreases the disruptions experienced by customers.
The functional benefits are clear, but the easy installation of Smartcloser compared recloser installation to normal outdoor transformer substation is a clear advantage. As it is installed directly to overhead line network, there is no need for substation building or underground cable installations.
”Smartcloser is easier and faster to install than recloser in substation. This was also proven in real life as installation was carried out without any big problems and the project was effortless as whole”, Rauhala continues.
Fastest way to provide uninterrupted electricity distribution
In Joensuu Smartcloser guards long overhead line typical for Finnish countryside where most of the electricity users are in the beginning of the power line. Usually each main substation feeder is one secured zone. But Smartcloser placed in Hammaslahti village has two protection zones: 20 kilometers from village's power station to recloser and 50 kilometers from recloser onwards through forests to the customers furthest away.
Trees falling on the line are the biggest cause for long disruptions, where short disruptions are mainly caused by thunder and birds. In the future, customers in the first protection zone will not be affected by faults that occur in middle of the forest behind the automatic recloser.
”Ensto Smarcloser is cheaper than recloser installed into a substation. It is the fastest way to improve the quality of electricity and provide uninterrupted electricity distribution for customers in the beginning of the power line”, tells Service and Development Manager Jukka Leppänen from PKS Sähkönsiirto Oy.
”Compared to remotely controlled load break switch Smartcloser detects faults behind it automatically, separates the faulty part of the network and functions as independent protection device. The number of faults will not decrease, but the size of the area impacted will, as faults "behind" the recloser will not affect the customers in the beginning of the power line. Smartcloser can also be used as switching device like a load break switch”.
Leppänen expects Smartcloser not only to improve the quality of electricity, but also the company image and decrease the disturbance caused by blackouts. According to Energy Department's surveillance model decline in disruptions in electricity distribution leads to smaller sanctions which enables companies to use more money to real network improvement work. Customers will also benefit as transfer prices will develop more moderately.
Operates also in compensated networks
”The electricity network in our area has been divided to three zones of which the first zone is the village area. We will install underground cables to this zonbe by the end of 2019. After this a half of our permanent customers belong to weatherproof network", tells Service Manager Matti Pesonen from PKS Sähkönsiirto.
”We are now installing reclosers to the border area of zone one and two, such as Hammaslahti. As the underground cabling progresses, we will install more reclosers between zones two and three.”
”This is a flexible and cost effective way to advance substantial project and bring more customers under the weatherproof distribution network. The aim is that in 2028 more than half of the entire electricity network has been cabled and 100% of our customers are benefiting from the weatherproof network. Reclosers play an important role in this.”
Pesonen reveals that the typical challenge for recloser is operating in compensated network. This is where supplier's customer-oriented approach is much appreciated.
”Ensto developed Smartcloser so that it can detect even small earth fault currents ja functions selectively with power station protection. We feel that our needs have been listened to and we have a solution that fits our needs. Soon after the installation we were able to see that the device functions in practice. Falling tree caused an earth fault, but Smartcloser immediately secured electricity distribution to the village center.”