Abb is renowned for various types of communication units. Spa zf is a fibre-optic cable and two types of cables used are plastic core cables and glass-fibre core cables. Plastic-core cables are applicable for shorter distances, i.E. Under 30 m, whereas glass-fibre cables can be used for distances up to 1000 m. The transmission distance is the distance between two adjacent bus connection modules, which means that the total length of the cable loop can be longer than the transmission distance given above. Salient features are as follows:
1 disturbance-free communication is achieved
2 light signals transmitted through optic fibers are completely immune to electrical and electromagnetic interference.
3 the conventional electrical pilot wires of a substation switchgear installation are replaced with fibre-optic cables which transfers measured values, control commands, status and event data, etc.
