Technical description
3 Supporting functions
3.4 Current transformer supervision
VM50.EN004
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117
Parameters of the cold load & inrush detection function
Parameter Value
Unit Description
Note
ColdLd -
Start
Trip
Status of cold load detection:
Cold load situation is active
Timeout
Inrush -
Start
Trip
Status of inrush detection:
Inrush is detected
Timeout
ILmax
A
The supervised value. Max. of
IL1, IL2 and IL3
Pickup
A
Primary scaled pick-up value
Idle
A
Primary scaled upper limit for
idle current
MaxTime
s
Set
Idle xImode Current limit setting for idle
situation
Set
Pickup
xImode Pick-up setting for minimum
start current
Set
80
ms
Maximum transition time for
start recognition
Pickupf2
% Pick-up value for relative
amount of 2
nd
harmonic, I
f2
/I
f1
Set
Set = An editable parameter (password needed)
3.4.
Current transformer supervision
The relay supervise the external wiring between the relay
terminals and current transformers (CT) and the CT them
selves. Furthermore, this is a safety function as well, since an
open secondary of a CT, causes dangerous voltages.
The CT supervisor function measures phase currents. If one of
the three phase currents drops below I
min
< setting, while
another phase current is exceeding the I
max
> setting, the
function will issue an alarm after the operation delay has
elapsed.
Setting parameters of CT supervisor CTSV ( ):
Parameter Value
Unit Default Description
Imax>
0.0 … 10.0
xIn
2.0
Upper setting for CT
supervisor
Imin<
0.0 … 10.0
xIn
0.2
Lower setting for CT
supervisor
t>
0.02 …
600.0
s 0.10
Operation
delay
CT on
On; Off
-
On
CT supervisor on event
CT off
On; Off
-
On
CT supervisor off event
