Protective Elements
V - Voltage Protection [27,59]
Available stages:
V[1] ,V[2] ,V[3] ,V[4] ,V[5] ,V[6]
If the VT measurement location is not at the bus bar side but at the output side,
the following has to be taken into account:
When disconnecting the line is it has to be ensured that by an
»External
Blocking«
undervoltage tripping of the U<-elements cannot happen. This is
realized through detecting of the CB position (via digital inputs).
When the aux. voltage is switched on and the measuring voltage has not yet
been applied, undervoltage tripping has to be prevented by an
»External
Blocking«
In case of an fuse failure, it is important to block the
»U<-stages«
so that an
undesired operation can be prevented.
To do this, set »
Meas Circuit Superv
« to “active” and activate the required VT
supervision module (e. g. LOP, VTS).
Moreover, set the tripping delay of the undervoltage protection
»t«
to some
value that is longer than the detection time of the VT supervision module. Take
into account the following times:
• VTS, fuse failure determination via digital input: 20 ms
• VTS, determination via measurements / internal calculation: 20 ms
• LOP, fuse failure determination via digital input: 20 ms
• LOP, determination via measurements / internal calculation: 30 ms
(The “digital input times” do not cover the time-span from the fuse failure
occurrence until the signal is available at the digital input.)
(For devices featuring the LOP module:)
The LOP
(Loss of Potential)
module has a fixed built-in undervoltage threshold
of 0.03⋅V
n
.
Therefore, while commissioning undervoltage protection, do not use a pickup
value »V<« below 0.03⋅V
n
because then the undervoltage module will always
be blocked before it can trip.
All voltage elements are identically structured and can optionally be projected
as over- or undervoltage element.
878 MCDGV4 DOK-HB-MCDGV4-2E
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