Croatia: Končar, Engineering Co. for Plant Installation & Commissioning Inc. has completed the replacement of the busbar system at the 400/110/30 kV Tumbri substation, near Zagreb.
The refurbishment included the replacement of the 400 kV double busbar system comprising main and auxiliary busbars.
The 400 kV switching station consists of the Melina, Krško 1, Krško 2 and Žerjavinec line bays, main busbar connection bay, auxiliary busbar connection bay, measurement bay and three transformer bays. Because of the importance of the 400/110/30 kV Tumbri substation, and in order to achieve a higher level of security and availability, it was necessary to refurbish the busbar systems of the 400 kV substation. As part of the refurbishment, the so-called Gerber girder supporting the busbar tubes was replaced with beams between the support insulators, and the number of the support insulators was doubled. This system, called “one beam – one range”, provides complete control over the behaviour of the busbar tubes and enables a greater load-bearing capacity of the support structure.
In order to preserve the stability of the power system the shutdown time for individual 400 kV bays had to be aligned with the annual schedule of the Zagreb Dispatch Center and the National Dispatch Center, and all the planned deadlines had to be met.