Application - ABB RED615 Technical Manual

1YHT530004D05 D
6.4.5
615 series
Technical Manual
active for 5 seconds, that is, the fuse failure outputs are deactivated
when the normal voltage conditions are restored.
The activation of the BLOCK input deactivates both FUSEF_U and FUSEF_3PH
outputs.

Application

Some protection functions operate on the basis of the measured voltage value in the
IED point. These functions can fail if there is a fault in the measuring circuits
between the voltage transformers and the IED.
A fault in the voltage-measuring circuit is referred to as a fuse failure. This term is
misleading since a blown fuse is just one of the many possible reasons for a broken
circuit. Since incorrectly measured voltage can result in a faulty operation of some
of the protection functions, it is important to detect the fuse failures. A fast fuse
failure detection is one of the means to block voltage-based functions before they
operate.
GUID-FA649B6A-B51E-47E2-8E37-EBA9CDEB2BF5 V1 EN
Figure 324: Fault in a circuit from the voltage transformer to the IED
A fuse failure occurs due to blown fuses, broken wires or intended substation
operations. The negative sequence component-based function can be used to detect
different types of single-phase or two-phase fuse failures. However, at least one of
the three circuits from the voltage transformers must not be broken. The supporting
delta-based function can also detect a fuse failure due to three-phase interruptions.
In the negative sequence component-based part of the function, a fuse failure is
detected by comparing the calculated value of the negative sequence component
voltage to the negative sequence component current. The sequence entities are
calculated from the measured current and voltage data for all three phases. The
purpose of this function is to block voltage-dependent functions when a fuse failure
Section 6
Supervision functions
597