10.1.3.5
Voltage restrained overcurrent protection for generator and step-up
transformer
M13088-158 v4
Example will be given how to use one CVGAPC function to provide voltage restrained
overcurrent protection for a generator. Let us assume that the time coordination study
gives the following required settings:
•
Inverse Time Over Current TOC/IDMT curve: ANSI very inverse
•
Pickup current of 185% of generator rated current at rated generator voltage
•
Pickup current 25% of the original pickup current value for generator voltages
below 25% of rated voltage
This functionality can be achieved by using one CVGAPC function. The following
shall be done in order to ensure proper operation of the function:
1. Connect three-phase generator currents and voltages to one CVGAPC instance
(for example, GF05)
2. Set
CurrentInput
to value
MaxPh
3. Set
VoltageInput
to value
MinPh-Ph
(it is assumed that minimum phase-to-phase
voltage shall be used for restraining. Alternatively, positive sequence voltage can
be used for restraining by selecting
PosSeq
for this setting parameter)
4. Set base current value to the rated generator current primary amperes
5. Set base voltage value to the rated generator phase-to-phase voltage in kV
6. Enable one overcurrent step (for example, OC1)
7. Select
CurveType_OC1
to value
ANSI Very inv
8. If required set minimum operating time for this curve by using parameter
tMin_OC1
(default value 0.05s)
9. Set
PickupCurr_OC1
to value 185%
10. Set
VCntrlMode_OC1
to
On
11. Set
VDepMode_OC1
to
Slope
12. Set
VDepFact_OC1
to value 0.25
13. Set
VHighLimit_OC1
to value 100%
14. Set
VLowLimit_OC1
to value 25%
Proper operation of the CVGAPC function made in this way can easily be verified by
secondary injection. All other settings can be left at the default values. Furthermore the
other built-in protection elements can be used for other protection and alarming
purposes.
10.1.3.6
Loss of excitation protection for a generator
M13088-182 v3
Example will be given how by using positive sequence directional overcurrent
protection element within a CVGAPC function, loss of excitation protection for a
1MRK 505 370-UUS A
Section 10
Multipurpose protection
Busbar protection REB670 2.2 ANSI
281
Application manual
Summary of Contents for RELION REB670
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