Section 11 Secondary system supervision
11.1 Fuse failure supervision SDDRFUF
11.1.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Fuse failure supervision SDDRFUF - -
11.1.2 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 earthed networks. It is based on the negative-sequence measuring
quantities, a high value of negative sequence voltage 3U
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 earthed networks. It is based on the zero sequence measuring quantities, a
high value of zero sequence voltage 3U
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.
1MRK 504 135-UEN A Section 11
Secondary system supervision
243
Technical manual
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