Fuse combination switch for medium voltage disconnector Driescher EN62271 - 5
Rated voltage 12, 24, 36 and 38.5 kV
Rated current 630 A and 1250 A
Switch-fuse combinations are used for operational medium voltage-side on and off switching of distribution transformers in secondary substations. They additionally have the task of protecting these transformers against the impact of internal and external faults.
These combinations comprise a functional unit of switch disconnectors and back-up fuses.
By means of the fuses the breaking capacity of the combination is extended beyond that of a simple switch disconnector up to the rated short-circuit breaking current.
The high-voltage high breaking capacity fuse, according to statistics of the VDN (German Association of Electricity Network Operators) is rated as reliable transformer protection. The h.v.h.b.c. fuse in combination with a switch disconnector provides a simple solution which is very economical to procure and run.
This provides a clear-cut advantage over a circuit breaker with the associated current transformers and overcurrent time protection.
Besides this, the h.v.h.b.c. fuse has a current limiting effect when short-circuits occur and reliably interrupts the fault current of the first half cycle.
These properties are advantageous for the dimensional design of the network.
