Functions
2.34 Rotor Earth Fault Protection R, fn (ANSI 64R)
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
242
2.34.2 Setting Notes
General
Rotor earth fault protection protection is only effective and accessible if address 160 ROTOR E/F has been set
= to Enabled. If the function is not required Disabled is set. Address 6001 ROTOR E/F serves to switch the
function ON or OFF or to block only the trip command (Block relay).
Also, configuration parameter 223 UE CONNECTION must be set to Rotor. If this is not the case, a voltage
U
RE
= 0 is displayed and evaluated, so that the protection remains blocked.
Pickup Values
Since the protection calculates the ohmic rotor-earth resistance from the values caused by the applied bias volt-
age, the thresholds for the warning stage (6002 RE< WARN) and for the trip stage (6003 RE<< TRIP) can be
set directly as resistance values. The default settings are sufficient for the majority of cases. These values can
be changed depending on the insulation resistance and the coolant. Care must be taken to allow a sufficient
margin between the setting value and the actual insulation resistance.
Time Delays
The time delay for the warning stage 6004 T-WARN-RE< is usually set to approximately 10 s, and the delay for
the trip stage 6005 T-TRIP-RE<< to approximately 0.5 s. The set times are additional delay times not includ-
ing the operating times (measuring time, dropout time) of the protective function.
Data for the Coupling to the Rotor Circuit
The setting of the coupling reactance 6006 X COUPLING and the series resistance 6007 R SERIES enable
the protection to calculate the earth resistance R
E
from the complex equivalent diagram of the coupling capac-
itance of the coupling unit, the series (e.g. measuring brush) resistance, the capacitance to earth of the excita-
tion circuit, and the earth resistance of the excitation circuit. The equivalent circuit according to the figure below
applies.
Figure 2-109 Equivalent Measuring Circuit for Rotor Earth Fault Protection
where:
U
RE
Rotor circuit bias voltage
I
RE
Earth current
X
Coupling
Total series reactance of the coupling circuit, consisting of coupling capacitance and induc-
tance (if applicable)
R
S
Total resistance of the coupling circuit, consisting of brush resistance, protection resistance
(if applicable) and damping resistance (if applicable)
C
E
Rotor earth capacitance
R
E
Rotor earth resistance
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