ABB RELION REX640 Technical Manual page 1251

Protection and control

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Table of Contents

1MRS759142 F

Technical data

Table 1188: DSOCPSCH Technical data

Characteristic

Operate time accuracy

Communication logic for residual overcurrent

RESCPSCH (ANSI 85 67G/N SCHLGC)

Identification

Function description

Communication logic for residual

Function block

Figure 709: Function block

Functionality

The communication logic for residual overcurrent function RESCPSCH is used to

achieve instantaneous fault clearing independent of the fault location on the

protected feeder. There are four available communication scheme types.

• 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 provided

by complementing the permissive schemes with an additional logic called the

unblocking function, which is also included in RESCPSCH.

If the permissive overreaching scheme is used, some of the power system

conditions require additional special logic circuits, such as the current reversal and

weak-end infeed logic for residual overcurrent function RCRWPSCH.

Technical Manual

±1.0 % of the set value or ±20 ms

identification

Protection related functions

ANSI/IEEE C37.2

device number