Overcurrent Protection With Undervoltage Seal-In - ABB Relion 670 Series Applications Manual

Section 7
Current protection
9. Set
10. Set
11. Set
All other settings can be left at the default values.
7.17.3.3

Overcurrent protection with undervoltage seal-in

To obtain this functionality, the IED application configuration shall include a logic in accordance to
figure 91
connected to VRPVOC. Let us assume that, taking into account the characteristic of the generator,
the excitation system and the short circuit study, the following settings are required:
• 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
2. Set
VBase and IBase equal to the rated phase-to-phase voltage and the rated phase current of the
generator.
3. Set
4. Set
5. Set
6. Set
stage is constant, irrespective of the magnitude of the generator voltage.
7. Set
8. Set
9. Set
10. Set
undervoltage stage.
The other parameters may be left at their default value.
200
VDepMode to Slope (default value).
VDepFact to the value 25% (default value).
VHighLimit to the value 100% (default value).
and, of course, the relevant three-phase generator currents and voltages shall be
Operation to Enabled .
GlobalBaseSel to the right value in order to select the Global Base Values Group with
StartCurr to the value 150 %.
Characteristic to IEC Def. Time .
tDef_OC to 6000.00 s, if no trip of the overcurrent stage is required.
VDepFact to the value 100 % in order to ensure that the pickup value of the overcurrent
Operation_UV to Enabled to activate the undervoltage stage.
StartVolt to the values 70 %.
tDef_UV to 3.0 s.
EnBlkLowV to Disabled (default value) to disable the cut-off level for low-voltage of the
1MRK 511 358-UUS A
GUID-B58E1CD6-F9AE-4301-ABE7-90DBFC987D69 v6
Application manual