ABB RET670 Commissioning Manual page 160

Section 11
Testing functionality by secondary injection
154
and the voltages that are related to them:
2
V Z I R
= × =
t FwdZ , FwdZ t FwdR
EQUATION14052 V1 EN
2
V Z I R
= × = +
t RvsZ , RvsZ t RvsR
EQUATION14053 V1 EN
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
SE (R , X ):
RvsR RvsX
V
VT s ,
V V 5899
= × =
t RvsZs , t RvsZ ,
V
VT p
,
EQUATION14055 V1 EN
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
maximum value 4) in order to reduce the magnitude of the test voltage for the points RE
and SE.
Test sets usually do not have a feature to simulate a real network during a power swing and
apply the related analog quantities at the terminal of the generator. The scope of the
present test is not a simulation of a real network. Voltages and currents are supplied in
order to measure an impedance that changes in the time and traverses the plane R-X and,
in particular, the area inside the lens characteristic. The test may be performed by
applying:
• Symmetric three-phase voltage at 50 Hz. The magnitude depends on the point of the
characteristic that needs to be verified. The following three main points of the line
segment SE-RE need to be checked:
2 2
X I 0 078 . 0 565 .
+ × = +
FwdX t
2 2
X I
0 003 . 0 282 .
× = +
RvsX t
0 1 .
V
86 45 .
× =
13 8 .
0 1 .
42 75 . V
× =
13 8 .
was calculated by using a factor 2.5 (instead of the
t
1MRK 504 165-UUS -
2
20918 0 570 0 20918 11931 .
× = × =
2
20918 0 282 2 20918 5899 .
× = × =
Transformer protection RET670 2.2 ANSI
Commissioning manual
V
(Equation 12)
V
(Equation 13)
(Equation 14)
(Equation 15)