EQUATION1816 V1 EN-US (Equation 233)
EQUATION2037 V2 EN-US (Equation 233)
VBase: The parameter VBase is set to the generator rated Voltage (phase-phase) in kV
.
9.14.3.4 Overcurrent protection with undervoltage seal-in
GUID-B58E1CD6-F9AE-4301-ABE7-90DBFC987D69 v6
To obtain this functionality, the IED application configuration shall include a logic in
accordance to figure
203 and, of course, the relevant three-phase generator currents and
voltages shall be 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 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 502 071-UUS A Section 9
Current protection
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 431
Application manual
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