MAX I
A I
B I
C
Start value
( _ , _ , _
)
×
(Equation 173)
The differential current is limited to 1.0 × In.
Figure 469: CCSPVC operating characteristics
When the differential current I_DIFF is in the operating region, the
FAIL
output is
activated.
The function is internally blocked if any phase current is higher than the set
Max operate current. When the internal blocking activates, the
FAIL
output is
deactivated immediately. The internal blocking is used for avoiding false operation
during a fault situation when the current transformers are saturated due to high
fault currents.
The value of the differential current is available in the monitored data view on
the LHMI or through other communication tools. The value is calculated with the
equation.
I
DIFF
I
A
I
B
I
C
I
REF
_
_
_
_
_
=
+
+
−
(Equation 174)
The
Start value setting is given in units of ×In of the phase current transformer.
The possible difference in the phase and reference current transformer ratios
is internally compensated by scaling
I_REF
with the value derived from the
Primary current setting values. These setting parameters can be found in the Basic
functions section.
The activation of the
BLOCK
input deactivates the
FAIL
output immediately.
Supervision functions
1MRS757644 H
878
620 series
Technical Manual
