6. Set base current value to the rated current of the protected object in primary
amperes
7. Enable one overcurrent step (for example, OC1)
8. Select parameter
CurveType_OC1
to value
IEC Def. Time
9. Set parameter
StartCurr_OC1
to value 5%
10. Set parameter
tDef_OC1
to desired time delay (for example, 2.0s)
Proper operation of CVGAPC function made in this way can easily be verified by
secondary injection. All other settings can be left at the default values. However it
shall be noted that set values for restrain current and its coefficient will as well be
applicable for OC2 step as soon as it is enabled.
Furthermore the other built-in protection elements can be used for other protection
and alarming purposes. For example, in case of generator application by enabling
OC2 step with set pickup to 200% and time delay to 0.1s simple but effective
protection against circuit breaker head flashover protection is achieved.
6.1.3.5
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
StartCurr_OC1
to value 185%
10. Set
VCntrlMode_OC1
to
On
11. Set
VDepMode_OC1
to
Slope
Section 6
1MRK 511 423-UEN A
Multipurpose protection
86
Bay control REC650 2.2 IEC
Application manual
Содержание 650 series
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