Stabilized And Instantaneous Differential Protection For Machines Mpdif; Identification; Function Block; Functionality - ABB RELION REX640 Technical Manual

1MRS759142 C
4.3.7
4.3.7.1
4.3.7.2
4.3.7.3
4.3.7.4
REX640
Technical Manual
Stabilized and instantaneous differential protection for
machines MPDIF

Identification

Function description
Stabilized and instantaneous differential
protection for machines

Function block

GUID-E0B32BFF-96AA-42C3-A37C-6776190C48A1 V1 EN
Figure 389: Function block

Functionality

The stabilized and instantaneous differential protection for machines function MPDIF
is a unit protection function. The possibility of internal failures of the machine is
relatively low. However, the consequences in terms of cost and production loss are
often serious, which makes the differential protection an important protection
function.
The stability of the differential protection is enhanced by a DC restraint feature. This
feature decreases the sensitivity of the differential protection optionally for a
temporary time period to avoid an unnecessary disconnection of the machine during
the external faults that have a fault current with high DC currents. MPDIF also
includes a CT saturation-based blocking which prevents unnecessary tripping in case
of the detection of the magnetizing inrush currents which can be present at the
switching operations, overvoltages or external faults.

Analog channel configuration

MPDIF has two analog group inputs which must be properly configured.
Table 642: Analog inputs
Input
I3P1
I3P2
Protection functions
IEC 61850 IEC 60617
identification identification
MPDIF 3dI>G/M
Description
Three-phase currents
Three-phase currents
Section 4
ANSI/IEEE C37.2
device number
87M/87G
703