12.6.6.1
Testing
The protection function uses measurement of the third-harmonic voltages in the
neutral point of the generator and on the generator terminal (broken delta voltage
transformer connection to the IED).
The test set shall be capable to generate third-harmonic voltages. One voltage (U
N3
)
is connected to the residual voltage input related to the terminal side of the generator.
The second voltage (U
N3
) is connected to the voltage input related to the neutral of the
generator. The angle between the injected third-harmonic voltages shall be adjustable.
en07000127.vsd
U
3N
U
3T
IEC07000127 V1 EN
Figure 50:
Typical phasor diagram for third harmonic voltages for healthy
machine
1.
Inject the following voltages: U
3T
= 15 V, U
3N
= 5 V and the angle between the
voltages = 180°. Check the monitored values of the following analogue signals:
E3 (the magnitude of the third-harmonic induced voltage in the stator), U
3N
: 5 V
(the magnitude of the third-harmonic voltage measured at the neutral side of the
generator), U
3T
: 15 V (the magnitude of the third-harmonic voltage measured at
the terminal side of the generator) and ANGLE: 180° (the angle between the
third-harmonic voltage phasors U
3N
and U
3T
). The value of E3 should be close
to the following value:
(
) (
)
2
2
3 N
3T
3T
E3
U
U
cos(ANGLE)
U
sin(ANGLE)
=
-
×
+
×
EQUATION2070 V1 EN
(Equation 100)
2.
Read the value of DU (differential voltage). The value of DU should be close to
the following value:
(
) (
)
2
2
3N
3T
3T
DU
U
U
cos(ANGLE)
U
sin(ANGLE)
=
+
×
+
×
EQUATION2071 V1 EN
(Equation 101)
3.
Decrease the value of the injected voltage U
3N
until the signal START3H is
activated. Check that
Section 12
1MRK502053-UEN B
Testing functionality by secondary injection
186
Generator protection REG670 2.0 IEC
Commissioning manual
Summary of Contents for REG670 2.0 IEC
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