Date Code 20000421 Maintenance and Testing 7-27
SEL-251, -2, -3 Instruction Manual
50L should not be internally or externally torque controlled (via ITC and ETC).
Enter the following example settings:
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50L = 4.00 amps secondary
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A4(2346) = TF trip failure condition
TR(1246) = 50L
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ETC(1) = NA
ITC(1) = NA
The setting entry NA (not applicable) leaves the designated variable blank
[e.g., ETC= ].
2. Using the SET G command (G signifies the global setting group - settings
common to all setting groups), enter the example settings:
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TDUR = 5 trip duration time (cycles)
TFT = 30 trip failure time (cycles)
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Connect a TRIP output contact to an external timer so that TRIP output contact
assertion starts the external timer. The trip failure timer in the relay also starts
when the TRIP output contact asserts.
The TRIP output contact remains asserted until the trip duration timer (TDUR)
expires and all programmable trip conditions (TR) go away. Additionally, all
overcurrent element pickups have to drop out or TARGET RESET must be
pushed to unlatch the TRIP output contact.
Connect the A4 output contact to the same external timer so that it stops timing
when A4 asserts. This indicates that the relay has failed to trip the circuit
breaker and interrupt the fault current within the time allotted by the TFT setting
(TFT = 30 cycles; A4 = TF, trip failure condition).
Apply 5 amps of current to one phase of the relay. The TRIP output contacts
will immediately assert (5 A > 50L = 4.00 A). The external and trip failure
timers start immediately.
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