Does IEC = IAC in protective relay curves ? 1

[bdn2004]

Basler provided printouts of their relay settings for new relays that replaced old ones in some old switchgear.
They specified E2 - IAC Extremely Inverse. EasyPower does not have that pick. It has: E2 - Extremely Inverse and C1 - IEC Extremely Inverse.
Note they specified IAC ... which isn't IEC.

Side by side, for the exact same settings the curves are way different.

 

[davidbeach]

IAC is a family of electromechanical relays while IEC is a family of standards used in much of the world that didn't use IAC relays.

When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.

-- Douglas Hofstadter, Jan 1982

 

[dpc]

The "E2" designation should define the curve shape. You can ask EasyPower to verify. IAC relays were produced for decades by General Electric. For compatibility purposes, some US relay manufacturers offered IAC equivalent curves in their digital relays. To add more confusion there are standard equations defined by IEEE for relay curves that are not the same as the IEC curves. In practice the main goal is to find a curve that works for your specific situation.

 

[bdn2004]

Good info. These are new Basler digital relays that are replacing older digital relays, GE MDP type, that are discontinued.
The new relays kept the same settings and the same curves you would think. Basler was to replace in kind.

Basler provided the Client settings in a printout form of what's programmed into the new relays that have yet to be installed.
They just asked us to update the info into the EasyPower model.

I'll see which one matches the existing the best - that should be the one Basler used. Seems it should match it perfectly.
Confusing in their printout the IAC initials in the curve type, not IEC. Thanks for explaining.

 

[cranky108]

I recall the old Basler manuals having a formula for the curves. Why not just use that?
Besides there were several curves in the IAC family, so which one is this?
Yes, I would go beck the easy power to correct there curves. At least that is what I do with Aspen.