Process bus replaces hard wired connections with communication lines. "Smart" CT's, PT's and switchgear continuously transmits data over the process bus and any upstream devices that wish to use the data for protection, measurements, metering, or monitoring do so by monitoring the communications. There are two type of 61850-9 (Process bus, communications):
1. 9-1, serial unidirectional multidrop point to point link.
2. 9-2, IEEE 802.3 based process bus, i.e. Ethernet.
To date (3-10-2011) we have no offering in meters or Sepam Relays that support process bus.