The TSL-11 protection is designed for single-busbar, switchable substations. It serves up to 8 bays with current circuits, can operate as a ZSZ, as a LRW or executing both of those functions together. The device is produced in a 19”/6U chassis. The modular construction enables adaptation to changing arrangement of a substation in case it is expanded. Universal modules enable easy adaptation of the device to change of the transformation ratio of the current transformers, by software change of setup. Actual state of connections of the substation is presented on a LCD touch screen. TSL-11 has internal event and fault recorders.