Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.3.7.5 Operation principle
The function can be enabled and disabled with the
Operation
setting. The
corresponding parameter values are "On" and "Off".
The operation of MPDIF can be described using a module diagram. All the modules
in the diagram are explained in the next sections.
OPR_LS
Through
fault
detection
BLK_OPR_LS
BLOCK
BLK_OPR_HS
I3P1
I3P2
OPERATE
INT_BLKD
DC restraint
Differential
and bias
calculation
OPR_HS
Biased low
stage
CT
saturation
based
blocking
Instan-
taneous
high stage
I_A1
I_B1
I_C1
I_A2
I_B2
I_C2
Figure 449: Functional module diagram
Differential and bias calculation
Differential calculation module calculates the differential current. The differential
current is the difference in current between the phase and neutral sides of the
machine.
The phase currents
and
denote the fundamental frequency components on
the phase and neutral sides of the current. The amplitude of the differential current I
d
is obtained using the equation (assuming that the positive direction of the current
is towards the machine):
1MRS759142 F
Protection functions
REX640
Technical Manual
789
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