ABB RELION REX640 Technical Manual page 542

Protection and control

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Protection functions

Function block

Figure 312: Function block

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.

Analog channel configuration

H3EFPSEF has three analog group inputs which must be properly configured.

Table 602: Analog inputs

There are a few special conditions which must be noted with the configuration.

Can be connected to GRPOFF if

See the preprocessing function blocks in this document for the possible

signal sources. The GRPOFF signal is available in the function block called

Voltage selection is set to "No voltage" or "Uo".

Voltage selection is other than "Uo".

Three-phase voltages Necessary when

age selection is set to "Uo", "Phase A", "Phase

B" or "Phase C"

Residual voltage (measured or calculated)

Voltage selection is set to

Necessary when

Residual voltage (measured or calculated)

1MRS759142 F

Technical Manual