and the voltages that are related to them:
V Z I R X I
t FwdZ FwdZ t FwdR FwdX t,
. . .= × = + × = + × =
2 2 2 2
0 078 0 565 20918 0 5700 20918 11931× = V
EQUATION14052 V1 EN (Equation 12)
V Z I R X I
t RvsZ RvsZ t RvsR RvsX t,
. . .= × = + × = + × =
2 2 2 2
0 003 0 282 20918 0 2822 20918 5899× = V
EQUATION14053 V1 EN (Equation 13)
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
FwdR
, X
FwdX
):
V V
V
V
V
t FwdZs t FwdZ
VT s
VT p
, ,
,
,
.
.
.= × = × =11931
0 1
13 8
86 45
EQUATION14054 V1 EN (Equation 14)
SE (R
RvsR
, X
RvsX
):
V V
V
V
V
t RvsZs t RvsZ
VT s
VT p
, ,
,
,
.
.
.= × = × =5899
0 1
13 8
42 75
EQUATION14055 V1 EN (Equation 15)
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
t
was calculated by using a factor 2.5 (instead of the
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:
Section 11 1MRK 504 165-UUS -
Testing functionality by secondary injection
154 Transformer protection RET670 2.2 ANSI
Commissioning manual
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