ABB 615 Series - Application

Fuse failure detection criterion Conditions and function response
Current and voltage delta function criterion If the current and voltage delta criterion detects a
fuse failure condition, but all the voltages are not
below the Seal in voltage setting, only the FUSEF_V
output is activated.
If the fuse failure detection is active for more than five
seconds and at the same time all the phase voltage
values are below the set value of the
Seal in voltage
setting with Enable seal in turned to "True", the
function activates the FUSE_3PH output signal.
External fuse failure detection
The MINCB_OPEN input signal is supposed to be
connected through a protection relay binary input to
the N.C. auxiliary contact of the miniature circuit
breaker protecting the VT secondary circuit.The
MINCB_OPEN signal sets the FUSEF_V output signal
to block all the voltage-related functions when MCB
is in the open state.
The DISCON_OPEN input signal is supposed to be
connected through a protection relay binary input to
the N.C. auxiliary contact of the line
disconnector.The DISCON_OPEN signal sets the
FUSEF_V output signal to block the voltage-related
functions when the line disconnector is in the open
state.
It is recommended to always set Enable seal in to "True". This secures that
the blocked protection functions remain blocked until normal voltage
conditions are restored if the fuse failure has been 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_V and FUSEF_3PH outputs.
6.5.5 Application
Some protection functions operate on the basis of the measured voltage value in the
protection relay point. These functions can fail if there is a fault in the measuring circuits
between the voltage transformer (or combi sensor or voltage sensor) and protection relay.
A fault in the voltage-measuring circuit is called 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 trip.
Section 6 1MAC059074-MB A
Supervision functions
870 615 series ANSI
Technical Manual