The currently marketed voltage limiters of class 2.2 (VLD-O+F) of the BVL-50-…-R02 and BVL-100-…-R02 series represent the second generation of the successful VLDs that today protect passengers and personnel in electrical railway systems worldwide.
Apart from some modifications to the electronics, the most striking change is the new robust connection bracket made of a special aluminium alloy, which, together with efficient heat sinks, contributes significantly to the heat dissipation of the powerful semiconductor switching elements. The result of this new design is the voltage limiter’s ability to handle unusually high medium-term currents, which occur during heavy train operation (for example in the underground).
The maximum current ratings of the BVL-100-…-R02 reach an unrivalled 1600A for a period of up to 30 seconds, which is the normal time required for start-up or regenerative braking of a train set, and which can handle the associated current loads with a large reserve. As a result, these voltage limiters can also be used in demanding applications where other protection elements fail, or where much more complex and expensive solutions would otherwise be required. In addition, the choice of bracket shape (‘L or ‘T’) allows the flexible adaptation of the product to the respective installation conditions, which simplifies and speeds up the installation.
An important role is also played by the fact that these are fully autonomous voltage limiters that do not require an external power source for their operation and they can also be used under difficult conditions and in places that are difficult to access.