Coordination of Reclosers used in Sectionalizing

[power82]

How do you coordinate the instantaneous settings of breakers and downstream sectionalizing reclosers without reducing the reach of the breaker?

 

[dpc]

You don't, unless you set some definite time delay on the instantaneous element.

That's the problem with instantaneous trip elements. They are normally set so that they do not reach past the next downstream zone.

However, if the breaker is reclosing, the instantaneous can be set lower since it will be disabled after the first one or two operations.

The inverse time element can be set to overreach if the time dial is set to coordinate with downstream protection.

 

[jghrist]

You have to add some time delay or use an inverse time overcurrent instead of instantaneous to coordinate with the downstream recloser "fast" curves. You also need to incorporate "sequence coordination", where the breaker relay senses a fault downstream of the line recloser, does not trip, but counts the fault so that after the line recloser recloses, the relay uses its delayed curve.

Other than this, you can allow both the line recloser and the breaker to trip initially and reclose. Disable the instantaneous after the first trip.

 

[SMB1]

Set your inst. element to cover the end of line faults. this normal practice to safe your Xfmr.