Siemens Energy has launched a recloser that operates with vacuum interrupters and integrated controller aimed at the market in countries with extensive medium-voltage overhead systems. Installed in an overhead line route or at the transformer substation, this circuit-beaker has the function of selectively disconnecting the system in case of a fault. If the fault is temporary, the system is automatically connected back to load shortly afterward. Siemens has been delivering its first series-produced reclosers since March 2008.
The Siemens recloser can be used as an efficient way to manage system faults in single-phase and three-phase medium voltage systems. It is generally installed on an overhead line tower, but it can also be used in a transformer substation. These circuit-breakers have been developed for operating currents up to 800 A and rated voltages of 15.5 kV to 38 kV, with short-circuit currents of between 12.5 kA and 16 kA.
In addition to the circuit-breaker, the recloser also comprises integrated sensors and the controller, which is a protection and control device. The controller measures overcurrents, times and voltages and controls the circuit-breaker switching processes on the basis of this data.
The special function that has given the recloser its name is the repeated automatic reclosing after temporary faults in the overhead line system. The controller also has additional remote supervision and measurement functions as well as its comprehensive protection functions. This includes in particular the functions for measuring system reliability indices. The Siemens circuit-breaker is also equipped with load management functions to increase supply reliability and to minimize failures. The controller is accommodated in a separate control cabinet which also contains the uninterruptible power supply, the drive electronics and a number of communications interfaces.