ABB RELION REX640 Technical Manual page 1241

Protection and control

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1MRS759142 F

In the permissive overreach scheme, the received signal CR_PRM, or CRL if the

unblocking function is enabled, is used to allow the overreaching zone Z2 to trip

(activation of the OPERATE output) after the settable pick-up delay

Time . The start signal from the overreaching zone is connected to the CACC input.

Activating the BLOCK input totally blocks the permissive overreach scheme. The

CS_PRM and OPERATE outputs can be blocked by the BLK_CS_OPR input.

Figure 706: Simplified functional diagram of the permissive overreach scheme

Directional comparison blocking scheme DCB

The directional comparison blocking scheme is enabled with

In the blocking scheme, the start signal from the reverse-looking zone Z3 is

connected to the CSBLK input to create a CS_BLOCKING signal. The starting of the

reverselooking zone indicates that the fault is located outside the protected feeder.

The duration of the CSBLK input signal can be prolonged with the

setting to ensure a sufficient duration of the CS_BLOCKING signal.

The blocking scheme is mainly used to allow the overreaching zone Z2 to trip

(activation of the OPERATE output) after the settable

elapsed, and if no blocking signal is received from the remote terminal. To prevent

a false trip in case of an external fault, the block signal CR_BLOCKING must be

received before the

overreaching zone Z2 is connected to the CACC input.

Technical Manual

Coordination Time has elapsed. The start signal from the

Coordination Time setting in the blocking scheme depends, for

example, on the communication system delay and on the terminal's

Protection related functions

Coordination Time has

Coordination

Scheme type =

Carrier Min Dur