Toshiba GR200 Series Instruction Manual page 396

Line differential protection ied

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CT failure detection (CTF)

If a failure occurs on the secondary circuit in the current transformer (CT), the operation in

relays cannot be obtained properly because the relays do not measure incoming currents

correctly. Therefore, the CT failure detection (CTF) function is provided to block operating the

upon occurrence of the CT failure. Accordingly, an alarm signal is issued if a CT failure

is detected by the CTF function; a detection signal by the CTF function blocks operating the

relay for the current monitor

After the disappearance of the CT failure, the CTF function can take account of the CT

secondary circuit being in healthy condition in the three-phase; the operation of the CTF

function is reset

the CTF alarm is automatically removed and then the user can find resetting the CTF alarm.

Note: The CTF function can block the operation in several relays, but it does not block

the operation in other relays. To know the blocking, refer sections of the respective

protection functions.

Note: The user can programmable the operation using the setting and the PLC signals.

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Several IED models do not have CTF detection features. To determine whether the

features are implemented in the IED or not, locate the IED ordering number; and check the

order number at "G&T position" referring to the comparison table below. For more information,

Appendix: Ordering

Table 2.31-1 Comparative table in respective ordering numbers

CTF detection (CTF)

✓: Applicable

. Thus, the blocked relays are allowed to operate again. Incidentally, issuing

NA: Not applicable

6F2S1914 (0.49)

Ordering No. at "G&T"

GRL200 (Soft 033 & 037)

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