ABB RELION REX640, Техническое руководство, Страница: 1276 / 1960

Current reversal logic
Current reversal logic is enabled by changing the value of the
Reversal mode setting
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
Reversal time). The
OPR_IRV
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
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.
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.
Level
detector
CR
CB_OPEN
ECHO
OPR_WEI
CR
Weak end
trip logic
Echo
logic
BLK_WEI1
BLK_WEI2
FF
BLOCK
URES
Uo
Figure 723: Functional module diagram of Weak-end infeed logic
The WEI logic is enabled using the
Wei mode setting.
• If
Wei mode = "Off", the WEI logic is disabled.
• If
Wei mode = "Echo", the WEI logic is enabled without Level detector.
• If
Wei mode = "Echo and Operate", the WEI logic is enabled with Level detector.
Protection related functions 1MRS759142 F
1276 REX640
Technical Manual