If the rated secondary current I
rs
of the analog channel is 1 A, then the maximum
current test I
ts
is
I
I
I
A
ts
ovrl
rs
≤
= ×
=
4
4
EQUATION14041 V1 EN
(Equation 1)
If the CT of the generator has ratio 9000/1 A, then in primary values
I
I
I
I
I
A
t
ovrl p
ovrl
rp
rs
≤
=
×
= ×
=
,
4
9000
1
36000
EQUATION14042 V1 EN
(Equation 2)
Reference is made to the numerical values of the example, explained in the “Setting
guidelines” of the
Application Manual
. A test current equal to 2.5 time the base current
of the generator is chosen; this choice is related to the selected test voltage that is
applied while testing the point SE and RE.
I
I
A
t
Base
=
×
=
×
=
2 5
2 5 8367 20918
.
.
EQUATION14043 V1 EN
(Equation 3)
The parameter
ReachZ1
defines the boundary between zone 1 and zone 2; it is
expressed in percent of the parameter
ForwardX
. If the setting of
ReachZ1
=
12%
,
then corresponding primary value of the reactance is
X
ReachZ
ForwardX
ZBase
RZ
1
1
100
100
12
100
59 33
100
0 9522 0
=
×
×
=
×
×
=
.
.
.0068
Ω
EQUATION14044 V1 EN
(Equation 4)
The calculation of the test voltage, that is related to
ReachZ1
, is based on the
impedance Z
RZ1
that has imaginary part X
RZ1
and real part R
RZ1
:
RRZ
achZ
ForwardR
ZBase
1
1
100
100
12
100
8 19
100
0 9522
0 0
=
×
×
=
×
×
=
Re
.
.
. 0
09
Ω
EQUATION14045 V1 EN
(Equation 5)
The magnitude of the impedance Z
RZ1
is:
2
2
2
2
1
1
1
0.009
0.068
0.069
RZ
RZ
RZ
Z
R
X
=
+
=
+
=
W
EQUATION14046 V1 EN
(Equation 6)
Hence the reference voltage of the test of the boundary between zone 1 and zone 2 is
V
Z
I
V
t RZ
RZ
t
,
.
1
1
0 069 20918 1435
=
×
=
×
=
EQUATION14047 V1 EN
(Equation 7)
If the test voltage is lower than V
t,RZ1
(or in opposition), then the test is related to the
zone 1; if the test voltage is higher than V
t,RZ1
, then the test is related to the zone 2.
Considering the resistances and reactances which are related to the settings
(
ForwardR
,
ForwardX
) and (
ReverseR
,
ReverseX
):
Section 12
1MRK502053-UEN B
Testing functionality by secondary injection
124
Generator protection REG670 2.0 IEC
Commissioning manual
Summary of Contents for REG670 2.0 IEC
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