Overcurrent Protection With Undervoltage Seal-In - ABB REG670 Applications Manual

1MRK 502 071-UEN -
9.14.3.4
9.15
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
IBase: The parameter IBase is set to the generator rated current according to
equation 240.
S
N
=
IBase
×
3 U
N
EQUATION1816 V1 EN
UBase: The parameter UBase is set to the generator rated Voltage (phase-phase) in
kV.

Overcurrent protection with undervoltage seal-in

To obtain this functionality, the IED application configuration shall include a logic in
accordance to figure 203
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:
• Start current of the overcurrent stage: 150% of generator rated current at rated
generator voltage;
• Start 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 On.
2. Set GlobalBaseSel to the right value in order to select the Global Base Values
Group with UBase 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 start value of the
overcurrent stage is constant, irrespective of the magnitude of the generator
voltage.
7. Set Operation_UV to On to activate the undervoltage stage.
8. Set StartVolt to the values 70%.
9. Set tDef_UV to 3.0 s.
10. Set EnBlkLowV to Off (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.
Generator stator overload protection GSPTTR
and, of course, the relevant three-phase generator currents
Section 9
Current protection
(Equation 240)
399