ABB RELION REX640 Technical Manual page 1237

Protection and control

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Table of Contents

1MRS759142 F

Identification

Function description

Scheme communication logic

Function block

Figure 702: Function block

Functionality

The scheme communication logic function DSOCPSCH is used to achieve

instantaneous fault clearing independent of the fault location on the protected

feeder. Several communication scheme types are available.

• Direct underreaching transfer trip DUTT

• Permissive underreaching transfer trip PUTT

• Permissive overreaching transfer trip POTT

• Directional comparison blocking scheme DCB

The directional comparison unblocking scheme DCUB can also be implemented

by complementing the permissive schemes with an additional logic called the

unblocking function, which is also included in DSOCPSCH.

If the permissive overreach scheme is used, some of the power system conditions

require additional special logic circuits, such as the current reversal and weak-end

infeed logic function CRWPSCH.

Operation principle

The function can be enabled and disabled with the

corresponding parameter values are "on" and "off".

The operation of DSOCPSCH can be described with a module diagram. All the

modules in the diagram are explained in the next sections.

Technical Manual

identification

Operation setting. The

Protection related functions

ANSI/IEEE C37.2

device number