Differential Slope 1 and 2

[Js20981]

What are we testing with the Slope test?

[Realtime]

What are we testing with the Slope test?

How little current your test set can output? :) :)

Seriously though, in a modern (digital) relay you are testing the settings (Slp1, Slp2, breakpoint between). The slope 2 is there because on a through fault, the CT's can misbehave and not supply accurate replicas of the primary signal. The larger % on slope 2 allows for greater mis match at current levels associated with a through fault. Slope 1 (on a Tx) is allowing for tap changer operations (+/-10 %).

It is just as important that the relay restrains for a through fault as well as it tripping for an internal fault.