SEL Relay CTR/CTRG/CTRN 1

[sky2020]

I was checking the actual Ig value and CTR was the correct value to multiply with the IG to get the actual Ig current. CTRN and CTRG were wrong values. Can I multiply IG * CTR to get the actual Ig?

PHASE CT RATIO 1–5000 CTR := 400
NEUTRAL CT RATIO 1–5000 CTRN := 120
IG SOURCE MEAS, CALC IG_SRC := MEAS
RESIDU CT RATIO 1–5000 CTRG := 120

 

[davidbeach]

What relay? I don't recall any that have both a CTRN and a CTRG.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[cranky108]

The 351 does, but I don't know what relay he is using.

 

[DTR2011]

If you wire the CTs in a residual connection through the 4th CT input (Ig or In), you can see both. Our distribution company does this on a 351A application to have more ground elements available.

 

[davidbeach]

Yes, you can wire it that way, but there's still only a CTR and a CTRN setting. The 'N' elements use the IN currents and the CTRN. The 'G' elements use the calculated residual value based on CTR. There is no CTRG.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[thermionic1]

I agree, the "CTRG" is the CTR for the phase CT's.

To clarify to OP:

Ig is calculated by the relay automatically and is based on the phase CTR. IN may meter something (noise), but if it is not wired to either a dedicated neutral CT or the residual connection of the phase CT's the metered value is useless.
By default, the front panel is set to display In, which could be misleading if In is not used. Ig can be set to display in the front panel.

If connected via computer, I think the Meter command will show both.