GE SR745 OLTC position correction

[schweiko]

I have to install two GE SR745 Xfmr management relays (main and backup)to protect one transsformer. My transformer is provided with OLTC with one set of resistors indicating the tap position to the protection. The question is if it's possibible to connect this one set of resistors to two SR745.

 

[dpc]

The SR-745 does provide for automatic ratio correction based on tap changer position. I applied a lot of SR-745 relays, but never used this feature. You'll have to check SR-745 manual to determine if your position indication system is compatible with the SR-745. I suspect it is, but don't have any actual experience with this feature.

 

[jwerthman]

I never use this feature on the SR745 relays. It's just more trouble than it's worth for the nominal reduction in slope that you could get in the settings. I don't really trust the resistor network to be reliable enough for use in a differential protection scheme anyway.