Voltage-Restrained Time Overcurrent Protection Vrpvoc - ABB REG670 Applications Manual

Section 9
Current protection
9.14
9.14.1
394
Where
U is the rated voltage of the generator
N
X '' is the subtransient reactance for the generator (Ω)
d
X is the reactance of the step-up transformer (Ω)
T
Z is the short circuit source impedance of the connected network recalculated to the
network
generator voltage level (Ω)
The setting can be chosen:
I > to be less than 0 8 . ⋅ I
energisation
EQUATION2283 V2 EN
tOC: Time delay for trip in case of high current detection due to accidental energizing
of the generator. The default value 0.03s is recommended.
ArmU<: Voltage level, given in % of UBase, for activation (arming) of the accidental
energizing protection function. This voltage shall be lower than the lowest operation
voltage. The default value 50% is recommended.
tArm: Time delay of voltage under the level Arm< for activation. The time delay shall
be longer than the longest fault time at short circuits or phase-earth faults in the
network. The default value 5s is recommended.
DisarmU>: Voltage level, given in % of UBase, for deactivation (dearming) of the
accidental energizing protection function. This voltage shall be higher than the
ArmU< level. This setting level shall also be lower than the lowest operation voltage.
The default value 80% is recommended.
tDisarm: Time delay of voltage over the level DisarmU> for deactivation. The time
delay shall be longer than tOC. The default value 0.5s is recommended.
Voltage-restrained time overcurrent protection
VRPVOC
Identification
Function description
Voltage-restrained time overcurrent
protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
IEC 61850 IEC 60617
identification identification
VRPVOC I>/U<
1MRK 502 071-UEN -
(Equation 239)
ANSI/IEEE C37.2
device number
51V
Application manual