Siemens 7SA522 Distance Relay Setting

[ElecDan]

Hello everyone,

I have an existing Quadramho relay setting (21 function). It has Zone 3 setting as forward and reverse (offset) settings. It gives me Offset Mho option to set. Now I need to transfer the same setting to a new Siemens 7SA522 relay.

Question: What would be the best way to set Zone 3 forward and reverse in the 7SA522 relay? 7SA522 does not provide Offset mho option. Thanks for any suggestions/ideas.

 

[odlanor]

Use Quadrilateral characteristic Z3 reverse and Z4 forward both with Z3 delay.

 

[ElecDan]

Hi odlanor,

Thanks for your comments. Is there any added benefit if I set to quad instead of mho? I know that in quad you get more resistive coverage, but if I don't need that, can just set to mho characteristics for both reverse and forward zones? Or it's the quad characteristics that would be somewhat closer to offset?

 

[odlanor]

Zone 3 is a remote backup protection. You are using the relay of one line to protect another line.
The classical setting is zone 1,2 and 3 forward. You can do it with 7SA522.

ref:Numerical distance protection - Gerhard Ziegler -Siemens book -
fig.24-pag. 32 - 1999

 

[ElecDan]

Thanks odlanor. Thanks also for the book you suggested.

 

[odlanor]

Zone 3 is a remote backup protection. You are using the relay of one line to protect another line.
The classical setting is zone 1,2 and 3 forward. You can do it with 7SA522
using MHO characteristics,.

ref:Numerical distance protection - Gerhard Ziegler -Siemens book -
fig.24-pag. 32 - 1999