ABB REC650 User Manual

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 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.
9.2.3 Function block
SDDRFUF
I3P*
U3P*
BLOCK
CBCLOSED
MCBOP
DISCPOS
BLKZ
BLKU
3PH
DLD1PH
DLD3PH
IEC08000220 V1 EN
Figure 89: SDDRFUF function block
1MRK 511 287-UEN A Section 9
Secondary system supervision
195
Technical manual

ABB REC650 Specifications

General

Brand	ABB
Model	REC650
Category	Control Unit
Language	English