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9.2.2
Functionality
The aim of the fuse failure supervision function SDDRFUF is to block voltage measuring
functions at failures in the secondary circuits between the voltage transformer and the IED
in order to avoid inadvertent operations that otherwise might occur.
The fuse failure supervision function basically has three different detection methods,
negative sequence and zero sequence based detection and an additional delta voltage and
delta current detection.
The negative sequence detection is recommended for IEDs used in isolated or high-
impedance grounded networks. It is based on the negative-sequence measuring quantities,
a high value of negative sequence voltage 3V
2
without the presence of the negative-
sequence current 3I
2
.
The zero sequence detection is recommended for IEDs used in directly or low impedance
grounded networks. It is based on the zero sequence measuring quantities, a high value of
zero sequence voltage 3V
0
without the presence of the zero sequence current 3I
0
.
For better adaptation to system requirements, an operation mode setting has been
introduced which makes it possible to select the operating conditions for negative
sequence and zero sequence based function. The selection of different operation modes
makes it possible to choose different interaction possibilities between the negative
sequence and zero sequence based detection.
A criterion based on delta current and delta voltage measurements can be added to the fuse
failure supervision function in order to detect a three phase fuse failure, which in practice
is more associated with voltage transformer switching during station operations.
9.2.3
Function block
ANSI08000220-1-en.vsd
SDDRFUF
I3P*
V3P*
BLOCK
52A
MCBOP
89B
BLKZ
BLKV
3PH
DLD1PH
DLD3PH
ANSI08000220 V1 EN
Figure 89:
SDDRFUF function block
1MRK 511 287-UUS A
Section 9
Secondary system supervision
207
Technical manual
Содержание REC650 ANSI
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