ABB RED615 Technical Manual page 448

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