Hello All,

This question is specific to setting the GE D60 line protection relay. I'm working with firmware v5.71 if that makes a difference...

I'm using CAPE to get my fault and apparent impedance values.

I am defining ZL0/ZL1 in my settings file. Both values are obtained from CAPE. My understanding is that this is being used by the relay to calculate K0 based upon my Zapp max from CAPE.

When I set my zone 1 ground reach, which I have defined as 0.75 * ZL1 (positive seq. impedance), I take the primary ZL1 value from CAPE, multiply it by my CT/PT ratio to get my secondary value, then multiply by 0.75 and enter this value (mag and angle) into the setting file.

Now, to my actual question:When I am setting the Z2 ground reach setting, I am using the definition 1.25 * (ZMA SLG), where ZMA SLG is the maximum apparent impedance from CAPE for a single-line to ground fault at the remote end. When I use my ZMA SLG value from CAPE I should also use the CT/PT ratio to find my secondary value. !BUT! do I apply zero-sequence compensation to this value prior to entering it into the settings file? I know I've already defined ZO/Z1 in the settings file, which is used for the relay to do zero-sequence compensation, specifically when it is doing its angle compare functions on measured vs. memorized values. I'm unsure if I should be using a (K0) compensated value of the Zapp max SLG value, which CAPE can give me quite easily, or do I simply enter the Zapp max SLG (secondary) value and let the relay do the compensation on the reach value on its own.

In summary,

When setting Z2 ground reach setting for the D60 should I apply zero-sequence (K0) compensation to my reach values prior to entering into the settings file.

Thanks in advance!marks1080 Great post!ReportRE: GE D60 v5.7x ground distance settingmarks1080 (Electrical) (OP)27 Jun 16 18:00 Bump.

Interested if anyone has dealt with this before. I had expected to get more replys.

Thanks!Mark Great post!ReportRE: GE D60 v5.7x ground distance settingHamburgerHelper (Electrical) 27 Jun 16 19:05 If I understand you correctly,

The relay trips on the equation for Zground. If you choose k to be very large for some reason, the impedance will be very sensitive to zero sequence current So, yes the impedance that you set the relay to trip needs to take k0M and K0 into account but Z2G normally should be close to Z2P with the same reach. If you are trying to figure out what the apparent impedance the relay sees due to infeed, plug VA, IA, and I0 into the equation.

Post EditedGreat post!ReportRE: GE D60 v5.7x ground distance settingsubmonkey (Electrical) 27 Jun 16 22:08 Hi marks1080,

The ground reach settings you enter arein positive sequence secondary ohms. Therelay uses the z0/z1 value to calculatethe z1 impedance between relay and fault,which is then compared to the ground reachsetting.

It isn't actually possible to apply theresidual compensation as you describe,

because the degree of adjustment dependson the ground current. The relay onlyknows the ground current when the faultoccurs.

I'd suggest once you finish your settingwork - simulate faults of different typesin CAPE and inject the calculated currentsand voltages into the relay. Check that therelay does what you expect for faults nearthe source bus, near the reach point, etc.

It's a very educational thing to do.

Also, note that in the D60 you enter theground reach for the quad elements as animpedance at the line angle, which is bothodd and annoying. For most civilised relaysyou just enter the reactance value.

Thanks,Alan

Great post!ReportRE: GE D60 v5.7x ground distance settingdavidbeach (Electrical) 28 Jun 16 02:35 As far as I know, the vast majority of line relays sold in North America have the ground quad "X" reach parallel to the line angle. That plus properly set k0 values mean that X can be set to the same value as the phase mho reaches. Great post!ReportRE: GE D60 v5.7x ground distance settingsubmonkey (Electrical) 28 Jun 16 10:58 Hi David,

Thanks for the comment - I've alwayswondered why GE did that. We stoppedusing mhos for phase distance yearsago, and from a quad/quad perspectivethe input format seems strange.

Thanks,Alan