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SEL-321 Out-of Step Protection Problem?
SEL 321
OSB upper tests fine, lower is no-op but 51g comes in
any ideas?I’m oversight on a project, test company is using a Doble 6150 w/ RTS, I’m not very familair with RTS
sdg
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If 51G is operating then it sounds like you are performing a phase to ground test. I’m not sure if K-factor comes into play on Out of step or not; but Out of Step is really a 3-phase problem and should be tested in three-phase mode. You’re not likely to slip a pole on only one phase.
What was the problem one might ask… the test routine for the 321 has an issue but it cannot be seen. More specifically, located under the “Static Specs” tab of the Lower OOS Trip (X6ABC) test, in the “Current” section, you will notice the “Freq” and “Harm” columns, they appear to say 60 and 1 respectively. Notice how I say “appear,” this is because the I1 Frequency is actually at 120Hz not 60Hz like it should be, therefore causing the test to fail. The solution is to click on the “Harm” button and click on “Harm 1” to ensure it is actually on “Harm 1” (60Hz). After doing this (not intentionally by the way) the Lower OOS Trip (X6ABC) test passes no problem and now I can sleep at night…
Provided by Relay Tech WB w/PGE
sdg