ABB RET670 Commissioning Manual page 156

Section 11
Testing functionality by secondary injection
150
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:
• the point RE (R
• a point which is related to the parameter ReachZ1 (boundary between
zone 1 and zone 2)
• the point SE (R
The phase angle of the test voltages is equal to:
• arctan (ForwardX/ForwardR) for tests in the quadrant 1 and 2 of the R-X
plane
• arctan (ReverseX/ReverseR) -180° for tests in the quadrant 3 and 4 of the R-X
plane
• Symmetric three-phase current, where the current is the summation of two
currents that have the same magnitude, but different frequencies.
I 20918
t
I I
= = =
50 tf
2 2
GUID-F02E8D18-FF87-45BE-8142-E8FA19F6966B V1 EN-US
The first current I
50
secondary) and phase angle 0º.
The second current I
phase angle 180º (at the starting time of the test) and frequency:
• 49.5 Hz for the test as generator in the quadrant 1 and 2 of the R-X plane
• 50.5 Hz for the test as generator in the quadrant 3 and 4 of the R-X plane
When the trajectory of the impedance, that is seen by the protection
function, traverses the lens characteristic then a pole slipping is
detected. The present procedure avoids tests of points of the line
SE-RE that are too close to the R-axis because in that case the
voltage is close to zero and, therefore, the impedance may approach
a not defined quantity 0/0.
, X )
FwdR FwdX
, X )
RvsR RvsX
A
10459
=
has frequency 50 Hz, magnitude 10459 A (that is, 1.162 A
has magnitude 10459 A (that is, 1.162 A secondary),
tf
1MRK 504 165-UEN A
(Equation 16)
Transformer protection RET670 2.2 IEC
Commissioning manual