ABB RELION RET670, Applications Manual

Page: 617 / 1016

• Pickup current of the overcurrent stage: 150% of generator rated current at rated
generator voltage;
• Pickup voltage of the undervoltage stage: 70% of generator rated voltage;
• Trip time: 3.0 s.
The overcurrent stage and the undervoltage stage shall be set in the following way:
1. Set Operation to Enabled .
2. Set GlobalBaseSel to the right value in order to select the Global Base Values
Group with VBase and IBase equal to the rated phase-to-phase voltage and the
rated phase current of the generator.
3. Set StartCurr to the value 150 %.
4. Set Characteristic to IEC Def. Time .
5. Set tDef_OC to 6000.00 s, if no trip of the overcurrent stage is required.
6. Set VDepFact to the value 100 % in order to ensure that the pickup value of the
overcurrent stage is constant, irrespective of the magnitude of the generator
voltage.
7. Set Operation_UV to Enabled to activate the undervoltage stage.
8. Set StartVolt to the values 70 %.
9. Set tDef_UV to 3.0 s.
10. Set EnBlkLowV to Disabled (default value) to disable the cut-off level for low-
voltage of the undervoltage stage.
The other parameters may be left at their default value.
1MRK 504 163-UUS A
Section 9
Current protection
Transformer protection RET670 2.2 ANSI 611
Application manual