CHAPTER 7: COMMISSIONING PROTECTION SCHEMES
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 7–55
7.5.19.4 Loss of Life Limit
Typical settings for the loss-of-life limit element dictate that either the limit be changed or
the initial transformer loss-of-life be changed temporarily. Verification of this function is
recommended by programming an initial loss-of-life above the element threshold. The
element operates instantly as it has no associated time delay.
7.5.20 Tap Monitor Failure
The tap monitor failure element operates when the sensed resistance is 150% larger than
the programmed values for the monitor circuit.
Connect a resistance to simulate the tap changer resistance and increase
this resistance until the element operates.
Calculate that the resistance at which the element operated is 150% of
the resistance that would be present at the maximum tap position.
Verify all relay, targets and messages for correct operation per
programmed values.
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