Section 11
Testing functionality by secondary injection
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.
2 5
.
I
=
×
t
EQUATION14043 V1 EN-US
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
ReachZ
X
=
RZ 1
EQUATION14044 V1 EN-US
The calculation of the test voltage, that is related to ReachZ1, is based on the impedance Z
imaginary part X
1
=
RRZ
EQUATION14045 V1 EN-US
The magnitude of the impedance Z
=
Z
RZ
1
EQUATION14046 V1 EN-US
Hence the reference voltage of the test of the boundary between zone 1 and zone 2 is
V
Z
=
,
1
t RZ
EQUATION14047 V1 EN-US
If the test voltage is lower than V
voltage is higher than V
Considering the resistances and reactances which are related to the settings (ForwardR, ForwardX) and
(ReverseR, ReverseX):
ForwardR
R
=
FwdR
EQUATION14048 V1 EN-US
ForwardX
X
=
FwdX
EQUATION14049 V1 EN-US
ReverseR
R
=
RvsR
EQUATION14050 V1 EN-US
ReverseR
X
=
RvsX
EQUATION14051 V1 EN-US
146
2 5 8367 20918
.
I
A
=
×
=
Base
1
ForwardX
×
×
ZBase
100
100
and real part R
RZ1
Re
achZ
1
ForwardR
×
×
ZBase
100
100
2
+
2
=
2
+
R
X
0.009
0.068
RZ
1
RZ
1
0 069 20918 1435
.
I
×
=
×
=
1
RZ
t
t,RZ1
, then the test is related to the zone 2.
t,RZ1
8 19
.
×
ZBase
=
×
100
100
59 33
.
×
ZBase
=
100
100
0 29
.
×
ZBase
=
×
0 9522 0 003
100
100
29 6
.
×
ZBase
=
×
100
100
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12
59 33
.
=
×
×
0 9522 0
.
100
100
:
RZ1
12
8 19
.
=
×
×
0 9522 0 0
.
100
100
is:
RZ1
2
=
W
0.069
V
(or in opposition), then the test is related to the zone 1; if the test
0 9522 0 078
.
=
.
Ω
×
0 9522 0 565
.
=
.
Ω
.
=
.
Ω
0 9522 0 282
.
=
.
Ω
=
.0 0 68Ω
=
. 0 0 9Ω
Transformer protection RET670
1MRK 504 165-UUS Rev. J
(Equation 7)
(Equation 8)
that has
RZ1
(Equation 9)
(Equation 10)
(Equation 11)
(Equation 12)
(Equation 13)
(Equation 14)
(Equation 15)
Commissioning manual