Hi,
I have recently attempted to introduce a Cisco IE-5000 as a timing source in a substation environment, providing PTP, IRIG-B analogue, and IRIG-B digital signals.
When comparing against the previous GNSS clock used in this installation (non-cisco), I have found using an IRIG-B analyzer that the Cisco IRIG-B outputs do not include the IEEE C37.118.1 extensions in the IRIG signal (on both analog and digital outputs).
The power protection equipment in use at the substation appears to ignore the IRIG-B signal, and when comparing against the original clock source, this is the only difference.
Also, the IRIG-B outputs appear to be rather weak, as the voltage on the IRIG bus drops to about 2.7V with a total line impedance of 27 ohms. I can't find anywhere in Cisco's documentation what the maximum line impedance accepted is. With other GNSS IRIG-B time clocks, they specify this, and its usually labelled at the IRIG output (e.g. about 18 ohms seems common in the industry).
Could Cisco please provide some feedback on this? For this particular work, we have had to abandon using a Cisco IE-5000 as an IRIG-B time source and implement a device from another vendor, which is a pain because the remainder of the substation network is all Cisco using PRP, PTP, GOOSE without any issue. If the IRIG side of things could be resolved, then it could be a full Cisco solution.
Regards,
Michael
