4.2.8.2 Function block
Figure 312: Function block
4.2.8.3 Functionality
The third harmonic-based stator earth-fault protection H3EFPSEF is used to detect
stator earth fault at the neutral point and at least up to 15...20% from the neutral
point along the stator winding. H3EFPSEF compares the third harmonic voltages
produced by the generator itself at both neutral and terminal side of the generator
for detecting earth fault.
H3EFPSEF provides two alternative protection methods:
• Differential of the third harmonic component measured both at generator
neutral and terminal side
• Neutral side third harmonic undervoltage
H3EFPSEF operates with the definite time DT characteristics.
H3EFPSEF contains a blocking functionality. Blocking deactivates all outputs and
reset timers.
4.2.8.4 Analog channel configuration
H3EFPSEF has three analog group inputs which must be properly configured.
Table 602: Analog inputs
Input Description
U3P
1
Three-phase voltages Necessary when
Volt-
age selection
is set to "Uo", "Phase A", "Phase
B" or "Phase C"
URES
2
Residual voltage (measured or calculated)
Necessary when
Voltage selection
is set to
"Uo"
UNEUT Residual voltage (measured or calculated)
See the preprocessing function blocks in this document for the possible
signal sources. The GRPOFF signal is available in the function block called
Protection.
There are a few special conditions which must be noted with the configuration.
1
Can be connected to GRPOFF if
Voltage selection
is set to "No voltage" or "Uo".
2
Can be connected to GRPOFF if
Voltage selection
is other than "Uo".
Protection functions 1MRS759142 F
542 REX640
Technical Manual
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