The traditional oil immersed construction used in the manufacture of shunt reactors typically consists of a winding and an iron core which are together housed in a steel tank that is filled with insulating oil.
Trench’s alternative “dry type” solution comprises of only a winding and support insulators. There is no iron core or steel tank. The insulation to ground is provided simply by the air space around the reactor winding and the support insulators.
In the past Trench dry-type air-core shunt reactors have only been applied at distribution class voltage levels. Typically they have been connected to the tertiary winding of a power transformer.
However due to the recent advances made in materials, and Trench’s novel design techniques, numerous high voltage dry-type air-core shunt reactors have now been designed, manufactured and installed - directly connected to the transmission systems at voltages up to and including 345 kV. In addition applications at 500 kV are presently being considered.
A factor driving the increase in demand for high voltage dry-type air-core reactors is the integration of renewable generation such as wind parks to the grid. The connecting overhead lines or cables require shunt compensation with ratings for reactive compensation in the range of some tens of Mvars. Usually such wind parks are located in environmentally sensitive areas thereby favoring Trench’s dry-type air-core technology.
Because these reactors have a low investment cost, require minimal maintenance, there is no oil spill or fire hazard, installation is fast and protection is simple, they are well suited for remote installations at any point along the power transmission lines. Because Trench dry-type air-core reactors are usually custom designed for each specification, the size, shape and layout of reactor modules can be modified to suit the particular requirements of each particular installation.
All the above makes the Trench dry type design a great alternative for Utility Engineers to consider.