6–50 345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
S3 PROTECTION CHAPTER 6: SETPOINTS
Slope setting, % = (36 A/693A)*100 = 5.1 %. Select 5% if the transformer is expected to run
most of the time at full load. If most of the time the transformer runs at lower than the
nominal loads, the slope setting can be set to higher value:
@ 70% load the slope setting would be: (36 / 485 A)*100 = 7%
@ 50% load the slope setting would be: (36 / 346 A)*100 = 10% \
@ 30% load the slope setting would be: (36 / 208 A)*100 = 17%
The ground current supervision feature and/or the RGF pickup time delay can be used if CT
saturation due to heavy external faults, is a concern.
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