ABB RET670 Commissioning Manual page 155

1MRK 504 165-UEN A
Transformer protection RET670 2.2 IEC
Commissioning manual
Testing functionality by secondary injection
Considering the resistances and reactances which are related to the settings
(ForwardR, ForwardX) and (ReverseR, ReverseX):
ForwardR
R ZBase
= ×
FwdR
100
EQUATION14048 V1 EN-US
ForwardX
X ZBase
= ×
FwdX
100
EQUATION14049 V1 EN-US
ReverseR
R ZBase
= ×
RvsR
100
EQUATION14050 V1 EN-US
ReverseR
X ZBase
= ×
RvsX
100
EQUATION14051 V1 EN-US
and the voltages that are related to them:
2
V Z I R
= × =
t FwdZ , FwdZ t FwdR
EQUATION14052 V1 EN-US
2
V Z I R
= × =
t RvsZ , RvsZ t RvsR
EQUATION14053 V1 EN-US
The previous calculations are in primary values. They are transferred to secondary
values to perform injections by a test set. Primary values are transferred to
secondary values by taking into account the CT ratio and the VT ratio (respectively
9000/1 A and 13.8/0.1 kV in the example).
The magnitude of the secondary voltages, that are related to the points RE and SE
of the R-X plane, needs to be checked.
RE (R , X ):
FwdR FwdX
V
VT s ,
V V 11931
= × =
t FwdZs , t FwdZ ,
V
VT p ,
EQUATION14054 V1 EN-US
SE (R , X ):
RvsR RvsX
V
VT s ,
V V 5899
= × =
t RvsZs , t RvsZ ,
V
VT p ,
EQUATION14055 V1 EN-US
The tests, which are described in this section, may require voltages that have
magnitude equal to 110% of the previous values. The continuous permissive
overload voltage of the protection voltage channels of the TRM module is 420 V;
so the previous voltages may be applied to the analog channels of the IED
continuously. Limitations may be related to the available test set; the current I
8 19 .
0 9522 0 078 . .
= × = Ω
100
59 33 .
0 9522 0 565 . .
= × =
100
0 29 .
0 9522 0 003 . .
= × = Ω
100
29 6 .
0 9522 0 282 . .
= × = Ω
100
2 2
X I 0 078 . 0 565
+ × = +
FwdX t
2 2
X I 0 003 . 0 282
+ × = +
RvsX t
0 1 .
86 45 . V
× =
13 8 .
0 1 .
42 75 . V
× =
13 8 .
Section 11
Ω
2
. 20918 0 570 0 20918 11931 .
× = ×
2
. 20918 0 282 2 20918 5899 .
× = ×
(Equation 8)
(Equation 9)
(Equation 10)
(Equation 11)
V
=
(Equation 12)
V
=
(Equation 13)
(Equation 14)
(Equation 15)
was
t
149