Hi
I have a one or two questions that I would like some clarity on regarding protection using directional overcurrent and earth fault protection.
1. When using a 90°-30° characteristic (30° RCA) why is it recommended that the relay is used for the protection of plain feeders with the zero sequence source behind the relaying point.
2. When using a 90°-45° why is it that the connection is recommended for the protection of transformer feeders or feeders that have a zero sequence source in front of the relay
3. When would one set the MTA or RCA different for phase faults as opposed to earth faults.
30°
4. If I use an older style 30° or 60°connection as opposed to a quadrature type connection is it true in saying the MTA would be at 30° and MTA is at 60° obviously in both cases the MTA is at the current for the faulted phase under consideration w.r.t its reference .
Much appreciated
I have a one or two questions that I would like some clarity on regarding protection using directional overcurrent and earth fault protection.
1. When using a 90°-30° characteristic (30° RCA) why is it recommended that the relay is used for the protection of plain feeders with the zero sequence source behind the relaying point.
2. When using a 90°-45° why is it that the connection is recommended for the protection of transformer feeders or feeders that have a zero sequence source in front of the relay
3. When would one set the MTA or RCA different for phase faults as opposed to earth faults.
30°
4. If I use an older style 30° or 60°connection as opposed to a quadrature type connection is it true in saying the MTA would be at 30° and MTA is at 60° obviously in both cases the MTA is at the current for the faulted phase under consideration w.r.t its reference .
Much appreciated