Supervision Functions
PRS-7367 241
activated with a fixed 10s delay. VT_InsAlm signal needs to be active during the delay.
When VT_InsAlm=1 and VT_Alm=0, Relay All Str=1 ( it means any protection start up and the
general relay startup signal become 1), then the VT_InsAlm will return.
The MINCB_OPEN input signal is supposed to be connected through an IED binary input to the
auxiliary contact of the miniature circuit breaker protecting the VT secondary circuit.
The MINCB_OPEN signal activates VT_InsAlm signal instantly to block all the voltage-related
functions when MINCB is in the open state. Similarly, VT_Alm output signal is activated with a
fixed 10s delay. VT_InsALM signal needs to be active during the delay.
The activation of the VT_Blk input deactivates the VT_Alm output.
Fuse failure reset
When fuse failure alarm signal is activated and MINCB is closed, the VT_Alm signal will
automatically reset after a fixed 1.25s delay if any of the following criterion is fulfilled.
The measured positive-sequence voltage exceeds the set PTS_U1 value;
3POLE_OPEN signal is activated;
4.4.3 PTS Application Scope
A fault in the voltage measuring circuit is referred to as a fuse failure. A fuse failure occurs due to
blown fuses, broken wires or intended substation operations. 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.
4.4.4 PTS Settings
Table 4.4-3 PTS settings
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