ABB REL 551 2.3 Series Installation And Comissioning Manual page 108


102
Line differential protection (DIFL)
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The injected current should be 4 times the operating current. The
time measurement is stopped by the trip output from the protec-
tion. The operating time should be 28-33 ms + 2 times the commu-
nication transmission delay.
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After the test mode is set to 2II, the command must be saved to ac-
tivate the protection. The yellow LED shall stop flashing.
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The I should be lower than 10% of the actual secondary current
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divided by the CTFactor, the I
This measurement is necessary at commissioning to guarantee that
there is no phase shift between the terminals.
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should be equal to this current.
Bias
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