ABB Relion 670 series, Technical Reference Manual

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13.8.11 Three phase undercurrent LCP3PTUC (37)
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Three phase undercurrent LCP3PTUC - 37
13.8.11.1 Introduction
Three phase undercurrent function (LCP3PTUC, 37) is designed for detecting loss of
load conditions.
Features:
• Phase wise pickup and trip signals
• Phase wise RMS current is available as service values
• Single definite time stage trip function
13.8.11.2 Principle of operation
Three phase undercurrent (LCP3PTUC, 37) is used for detecting sudden load loss
which is considered as fault condition. LCP3PTUC (37) starts when the current is less
than the set limit
PU_37 . It operates with definite time (DT) characteristics, that is, the
function operates after a predefined time tUC and resets when the load current restores.
The function contains a blocking functionality. It is possible to block the function
output, timer or the function itself, if desired.
13.8.11.3 Function block
ANSI09000772-1-en.vsd
LCP3PTUC (37)
I3P*
BLOCK
BLKTR TRIP
TR_A
TR_B
TR_C
RI
BFI_A
PU_B
BFI_C
ANSI09000772 V1 EN
Figure 426: LCP3PTUC (37) Function block
1MRK505222-UUS C
Section 13
Scheme communication
855
Technical reference manual