VAMP 140 - Second Harmonic Stage; Inrush (68)

VAMP Ltd Overcurrent and earth-fault relay
Technical description
VAMP 140
VM140.EN011 Vamp 24h support phone +358 (0)40 573 6316
15
Parameters of the unbalance protection stage:
I
2
> (46)
Parameter: Value/unit:
Measured
value
I2/I1 %
Negative phase sequence
current I2/I1
I2> % Setting value
Setting
values
t> s Operation time
SCntr Start counter (Start) reading
TCntr Trip counter (Trip) reading
Flt % Max. fault current
Recorded
values
Edly %
Elapsed time as compared to
the set operate time, 100% =
tripping
2.2.4. Second harmonic stage / inrush (68)
This stage is mainly used to block other stages. The ratio
between the second harmonic component and the fundamental
frequency component is measured on all the phase currents.
When the ratio in any phase exceeds the setting value, the
stage gives a start signal. After a settable delay, the stage gives
a trip signal.
The start and trip signals can be used for blocking the other
stages. The trip delay is irrelevant if only the start signal is
used for blocking.
The trip delay of the stages to be blocked must be more than 60
ms to ensure a proper blocking.
&
t
&
&
Im1
Im2
Im3
MAX
2ndHarm
t s
t r
>
Start
Trip
Register
event
Register
event
Setting
2.Harm
Block
Delay
Enable events
Figure 2.2.4-1. Block diagram of the second harmonic stage.