directional current protection (67) + open delta transformer

[Prieto]

Doubt:
We need to implement a directional current protection (67) using Multilin relays UR-F60. The potential transformers are connected in open delta. Until now, the protection has worked well as alarm, but in several forums that we have reviewed, it is said that it will not work because there is no reference to phase voltages; however, it has operated well when there have been faults upstream of the utility.

Question: Can this protection be done with transformers connected in open delta or not?

 

[davidbeach]

It can provide phase directional but not ground directional protection.

 

[vijaypandiyan]

it would have tripped on non directional. maybe the 67 protection was kept OFF

Thanks,
Vijay

 

[Prieto]

Thank you all for your answer. I add more details for a better analysis. The company is powered by two transformers 110/13.8kV delta/star with neutral grounded by resistance. Directional protection (67) is on the 13.8kV side. What would be the most recommended operating angle: 30 or 45 degrees?