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VAMP Ltd
Arc protection system
Operation and configuration instructions
VAMP 221
VM221.EN013
VAMP 24h support phone : +358 (0)20 753 3264
35
Unbalance fault (fault code18)
Power
Com
Error
Trip 4
Trip 2
Trip 3
I>int.
I>ext.
Trip 1
VAMP 221
Arc Protection Relay
Run
Install
Info
Temp set
Temp
Current
Error code
front_error18
Figure 3.1.4-6 The system indicates that the current measuring unit has
detected significant unbalance between the measuring channels.
This fault code indicates that the measuring channels of the
current measuring unit connected to the system have detected
significant unbalance between the different measuring
channels. If the channel I
L2
/I
0
of the current measuring unit is
used to measure phase current, the I
L2
/I
0
settings must be the
same as for I
L1
/I
L3
. In this case the I
L2
/I
0
channel is also covered
by the unbalance alarm; otherwise, the system only compares
the unbalance between two phase currents.
The factory setting for unbalance is 20% of the measured
currents. The alarm does not function with currents below 5
%*I
n
, which effectively prevents false alarms.
Potential causes:
1.
The current transformers connected to the current
channels have different transformation ratios.
Corrective measures:
•
Check the transformation ratios. The zero current
measurement is normally connected to the I
L2
/I
0
channel. This makes it possible to set different values
to the channels.
•
Connect similar current transformers to the I
L1
and I
L3
channels.
2.
The secondary circuit of the current transformers is
short-circuited.
Corrective measures:
•
With a clip-on ammeter, check whether the measuring
current travels through the current measuring unit.
•
Check which other components are connected to the
current circuit and whether the current travels
through them,
•
Once you have found the short circuit, check the status
of the current circuit before removing the short circuit.