VAMP 265, Operation And Configuration Instructions

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2.13 Inverse time operation 2 Protection functions Technical description
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
Fully programmable inverse delay characteristics
Building the characteristics by setting 16 [current, time]
points. The relay interpolates the values between given
points with 2nd degree polynomials. This mode is activated
by setting curve family to „PrgN‟'. There are maximum three
different programmable curves available at the same time.
Each programmed curve can be used by any number of
protection stages. See chapter 2.13.3.
Local panel graph
The relay will show a graph of the currently used inverse delay
on the local panel display. Up and down keys can be used for
zooming. Also the delays at 20xI
SET
, 4xI
SET
and 2xI
SET
are
shown.
Inverse time setting error signal
If there are any errors in the inverse delay configuration the
appropriate protection stage will use definite time delay.
There is a signal „Setting Error‟ available in output matrix,
which indicates three different situations:
1.
Settings are currently changed with VAMPSET or local
panel, and there is temporarily an illegal combination of
curve/delay/points. For example if previous settings were
IEC/NI and then curve family is changed to IEEE, the
setting error will active, because there is no NI type
available for IEEE curves. After changing valid delay type
for IEEE mode (for example MI), the „Setting Error‟ signal
will release.
 There are errors in formula parameters A…E, and the
device is not able to build the delay curve

There are errors in the programmable curve configuration
and the device is not able to interpolate values between the
given points.
Limitation
The maximum measured phase current is 50xI
n
and the
maximum directly measured earth fault current is 5xI
0n
. This
limits the scope of inverse curves when the setting is more than
2.5xI
n
(overcurrent stages and earth fault stages using I
0Calc
input) or 0.25xI
01n
(earth fault stages using I
01
input or I
02
input). The I
n
and I
01n
and I
02n
depend on the order code (See
chapter 12). The table below gives the limit values in secondary
amperes.