ABB RELION REX640 Technical Manual page 1185

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1MRS759142 C

Technical Manual

Current reversal logic

Current reversal logic is enabled by changing the value of the Reversal mode setting to

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.

GUID-48942739-E438-4C52-B5B0-7E575FA89A33 V1 EN

Functional module diagram of Weak-end infeed logic

The WEI logic is enabled using the Wei mode setting.

Protection related functions

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