U V V
s
=
× +
≈
12600 0 26 0 18
240
23
( . . )
GUID-7AA079B9-4E11-48BD-A474-B7A06BA3976B V1 EN
According to the criterion, the value of U
k
should be 2 · U
s
= 2 · 23 V = 46 V. It
depends on if the stability of the scheme is achieved with U
k
= 40 V. Otherwise, it
is possible to choose a bigger core of 65 percent with:
R
in
= 0.47 Ω (value given by the manufacturer).
U
k
= 81 V (value given by the manufacturer).
R
m
= 0.18 Ω
U V V
s
=
× +
≈
12600 0 47 0 18
240
34
( . . )
GUID-F7AF5A9B-A4F3-4714-94D2-022A54232F0E V1 EN
U
k
= 2 · U
s
= 68 V (required value).
As mentioned earlier, I
m
= 0.5 · I
e
gives a realistic value for I
prim
in
Equation 64. If
I
u
= 0 and I
rs
= m · 0.5 · I
o
, the value for the sensitivity is:
I
prim
= n · m · I
e
= 240 · 4 · 0.055 A ≈ 53 A
I
rs
= 4· 0.5 · 0.055 A = 0.11 A
The setting value can be calculated with:
Operate value
I
I
A
A
rs
CT n
=
=
≈
_
.
. %
2
0 11
5
2 2
GUID-C03C3B3E-E03F-41F3-B51A-A9AA161BC433 V1 EN
The resistance of the stabilizing resistor can be calculated:
R
s
= U
s
/ I
rs
= 34 V / 0.11 A ≈ 309 Ω
However, the sensitivity can be calculated more accurately when the actual values
of I
u
and I
rs
are known. The stabilizing resistor of the relay is chosen freely in the
above example and it is assumed that the resistor value is not fixed.
Section 4 1YHT530004D05 D
Protection functions
442 615 series
Technical Manual
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