Hitachi RET670 Commissioning Manual page 145

1MRK 504 165-UEN Rev. K
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
has imaginary part X
RRZ 1 =
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
=
t RZ , 1
EQUATION14047 V1 EN-US
If the test voltage is lower than V
test 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
X =
FwdX
EQUATION14049 V1 EN-US
ReverseR
=
R
RvsR
EQUATION14050 V1 EN-US
=
X
RvsX
EQUATION14051 V1 EN-US
and the voltages that are related to them:
V Z
=
t FwdZ ,
EQUATION14052 V1 EN-US
V Z
=
t RvsZ ,
EQUATION14053 V1 EN-US
Transformer protection RET670
Commissioning manual
1 ForwardX
× × ZBase
100 100
and real part R
RZ1
Re achZ 1 ForwardR
× × ZBase
100 100
2 + 2 = 2 +
R X 0.009
RZ 1 RZ 1
0 069 20918 1435 .
I
× = × =
RZ 1 t
, then the test is related to the zone 2.
t,RZ1
8 19 .
× ZBase =
100 100
ForwardX 59 33 .
× ZBase =
100 100
0 29 .
× = ×
ZBase
100 100
29 6 .
ReverseR
× = ×
ZBase
100 100
2 2
I R X
× = +
FwdZ t FwdR FwdX
2 2
I R X
× = +
RvsZ t RvsR RvsX
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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
0.068 0.069
V
(or in opposition), then the test is related to the zone 1; if the
t,RZ1
× 0 9522 0 078 . = . Ω
× 0 9522 0 565 . = . Ω
0 9522 0 003 . = . Ω
0 9522 0 282 . = . Ω
2 2
I 0 078 . 0 565 . 20918 0 570 0 20918 11931
× = + ×
t
2 2
I 0 003 . 0 282 . 20918 0 282 2 20918 5899
× = + ×
t
Testing functionality by secondary injection
= .0 0 68Ω
= . 0 0 9Ω
.
= × =
.
= × =
Section 11
(Equation 8)
that
RZ1
(Equation 9)
(Equation 10)
(Equation 11)
(Equation 12)
(Equation 13)
(Equation 14)
(Equation 15)
V
(Equation 16)
V
(Equation 17)
139