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3.3.7
Checking the Rotor Earth Fault Protection at Standstill
Rotor Earth Fault Protection (R, fn)
The rotor earth fault protection can be checked with the machine at standstill. For this purpose, the coupling
device must be fed an external AC voltage. This may be 100 V to 125 V or 230 V (see also connection example
in Section 2.34).
Switch rotor earth fault protection (address 6001 ROTOR E/F) to Block relay.
In the case of machines with rotating rectifier excitation (following Figure, left), a dead earth fault is applied
between the two measurement slip rings with measurement brushes in place, for machines with excitation via
slip rings (following Figure, right) between one slip ring and earth. The device now measures as earth imped-
ance only the reactance of the coupling unit and the brush resistance (as the case may be in series with a pro-
tection resistor for the coupling capacitors and a current-limiting resistor with inductive/capacitive coupling).
These values can be read out with the phase angle of this complex resistance under the earth fault measured
values:
Rtot
Xtot
ϕZtot
R
corresponds to the series resistance (brushes plus protection and limiting resistor) and X
tot.
reactance. If both for R
polarity. Change the polarity of one of the connections and repeat the measurement.
It must then be checked/remedied that the setting values
R SERIES
X COUPLING
correspond to the above values. Remove earth fault bridge.
Now using a resistor of the size of the warning resistance (RE< WARN, address 6002, 10 kΩ on delivery) an
earth fault is simulated as above. The earth resistance calculated by the unit can be read out under the Oper-
ational Measured Values as R
resistances, the matching improvement can be attempted by correcting the preset angle error forI
at address 6009. This angle error correction is only effective for the rotor earth fault protection function.
An earth fault is now simulated as above using a resistor of approximately 90% of the trip resistance (RE<<
TRIP, address 6003, 2 kΩ on delivery). The rotor earth fault protection initiates a pickup signal and after 6005
T-TRIP-RE<< (0.5 s on delivery) a trip indication (LED 1 and output relay 2), in both cases as a group indica-
tion device trip).
For machines with excitation via slip rings, the last test is repeated for the other slip ring.
Remove earth fault resistor.
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
= x.xx kΩ
= y.yy kΩ
= z.z °
and for X
values are indicated as 0, then the connections of U
tot.
tot.
= xxx Ω (address 6007)
= yyy Ω (address 6006)
. If substantial deviation occurs between the actual and the indicated earth
earth
Mounting and Commissioning
3.3 Commissioning
to the coupling
tot.
or I
have wrong
RE
RE
PHI I RE
RE
407
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