I
A
A
A
A
prim
=
⋅
+
⋅
+
(
)
≈
1000
0 020
2 0 0085
0
37
.
.
(Equation 123)
The power of the stabilizing resistor is calculated as follows.
P
V
W
≥
(
)
≈
323
3900
27
2
Ω
(Equation 124)
and
, the need for voltage dependent resistor is
checked.
U
A
kV
max
.
.
.
.
=
⋅
⋅
+
+
+
(
)
≈
12 770
1000
3900
15 3
1 73
0 10
36 2
Ω
Ω
Ω
Ω
(Equation 125)
˘
.
u
V
V
V
kV
=
⋅
⋅
−
(
)
≈
2 2 323
36200
323
9 6
(Equation 126)
The voltage dependent resistor, one for each phase, is needed in this case because
the voltage during the fault is much higher than 2 kV.
The leakage current through the varistor at the stabilizing voltage can be available
from the varistor manual, assuming that to be approximately 2 mA at stabilizing
voltage.
Iu
A
≈
0 002
.
(Equation 127)
The sensitivity of the protection can be re-calculated taking into account the
leakage current through the varistor as per
I
A
A
A
A
prim
=
⋅
+
⋅
+
(
)
≈
1000
0 020
2 0 0085
0 002
39
.
.
.
(Equation 128)
4.3.6.8
Signals
Table 532: MHZPDIF Input signals
Name
Type
Default
Description
ID_A
REAl
0.0
Differential current
amplitude (DFT)
phase A
ID_B
REAL
0.0
Differential current
amplitude (DFT)
phase B
Table continues on the next page
1MRS757644 H
Protection functions
620 series
Technical Manual
607
