ABB RELION REX640 Technical Manual page 1267

Protection and control

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1MRS759142 F

Figure 717: Functional module diagram

Current reversal logic

Current reversal logic is enabled by changing the value of the

This logic uses the start signal of the reverse-looking zone (Z3) 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 zone is activated after a start delay (the

time setting), the logic is ready to issue an OPR_IRV output signal. The OPR_IRV

signal is connected to the BLK_CS_OPR input of DSOCPSCH in order 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.

The BLK_IRV input is used to block the activation of the OPR_IRV output. The

BLK_IRV input is typically connected to the forward-looking zone start signals

within the terminal. General blocking is achieved by activating the BLOCK input.

Weak-end infeed logic

Weak-end infeed logic is used to activate the distance 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 CR signal is logically

combined with the local criteria to initiate the tripping of the weak-end breaker. The

received signal is echoed back to accelerate the tripping in the opposite end with

the stronger source.

Technical Manual

An internal 10 ms drop-off timer enables the current reversal logic to be

activated for the short-duration input signals even if the

time setting is set to zero.

Protection related functions

Reversal mode setting

Reversal reset