ABB RELION REX640 Technical Manual page 1276

Protection and control
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Protection related functions
Current reversal logic
Current reversal logic is enabled by changing the value of the
to "On".
Current reversal logic uses the start signal of the reverse directional residual
overcurrent function connected to the IRV input, which is used to recognize the
fault in the reverse direction, that is, in the parallel feeder. When the reverse
directional residual overcurrent function is activated, the logic is ready to issue
an OPR_IRV output signal after a start delay (setting
signal is connected to the BLK_CS_OPR input of the scheme communication logic
function to block the sending of the carrier send signal (CS) and the activation of
the OPERATE output of the communication logic. The OPR_IRV signal has a drop-off
delay defined with the
The BLK_IRV input is used to block the activation of the OPR_IRV output. The
BLK_IRV input is typically connected to the start signals of the forward-looking
residual overcurrent function in the terminal. General blocking is achieved by
activating the BLOCK input.
Weak-end infeed (WEI) logic
The WEI logic is used to activate the residual overcurrent protection function when
the fault current infeed is too low due to, for example, high source impedance or
fault current distribution between sources. When activated, the carrier receive (CR)
signal is logically combined with the local criteria to initiate the tripping of the
weak-end breaker. The received signal is also echoed back to accelerate the tripping
at the opposite end with the stronger source.
CB_OPEN
BLK_WEI1
BLK_WEI2
Figure 723: Functional module diagram of Weak-end infeed logic
The WEI logic is enabled using the
• If
• If
• If
1276
Reversal reset time setting.
An internal 10 ms drop-off timer is provided which ensures the current
reversal logic is activated for short-duration input signals, even if the
Reversal reset time setting is set to zero.
Uo
URES
detector
CR
FF
BLOCK
Wei mode = "Off", the WEI logic is disabled.
Wei mode = "Echo", the WEI logic is enabled without Level detector.
Wei mode = "Echo and Operate", the WEI logic is enabled with Level detector.
Level
Echo
logic
Wei mode setting.
1MRS759142 F
Reversal mode setting
Reversal time ). The OPR_IRV
Weak end
OPR_WEI
trip logic
ECHO
Technical Manual
CR
REX640

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