ABB REC670 Applications Manual page 239

1MRK 511 401-UEN A
Bay control REC670 2.2 IEC
Application manual
Operation: Off/On.
UBase (given in GlobalBaseSel): Base voltage phase to phase in primary kV. This
voltage is used as reference for voltage setting. OV2PTOV measures selectively
phase-to-earth voltages, or phase-to-phase voltage chosen by the setting ConnType.
The function will operate if the voltage gets lower than the set percentage of
UBase. When ConnType is set to PhN DFT or PhN RMS then the IED
automatically divides set value for UBase by √3. When ConnType is set to PhPh
DFT or PhPh RMS then set value for UBase is used. Therefore, always set UBase
as rated primary phase-to-phase voltage of the protected object. If phase to neutral
(PhN) measurement is selected as setting, the operation of phase-to-earth over
voltage is automatically divided by sqrt3. This means operation for phase-to-earth
voltage over:
> ×
U (%) UBase kV ( ) / 3
and operation for phase-to-phase voltage over:
> ×
U (%) UBase(kV)
EQUATION1993 V1 EN-US
The below described setting parameters are identical for the two steps (n = 1 or 2).
Therefore the setting parameters are described only once.
Characteristicn: This parameter gives the type of time delay to be used. The setting
can be Definite time, Inverse Curve A, Inverse Curve B, Inverse Curve C or I/Prog.
inv. curve. The choice is highly dependent of the protection application.
OpModen: This parameter describes how many of the three measured voltages that
should be above the set level to give operation. The setting can be 1 out of 3, 2 out
of 3, 3 out of 3. In most applications it is sufficient that one phase voltage is high to
give operation. If the function shall be insensitive for single phase-to-earth faults 1
out of 3 can be chosen, because the voltage will normally rise in the non-faulted
phases at single phase-to-earth faults. In subtransmission and transmission
networks the UV function is mainly a system supervision function and 3 out of 3 is
selected.
Un>: Set operate overvoltage operation value for step n, given as % of UBase. The
setting is highly dependent of the protection application. Here it is essential to
consider the maximum voltage at non-faulted situations. Normally this voltage is
less than 110% of nominal voltage.
tn: time delay of step n, given in s. The setting is highly dependent of the protection
application. In many applications the protection function is used to prevent
damages to the protected object. The speed might be important for example in case
of protection of transformer that might be overexcited. The time delay must be co-
ordinated with other automated actions in the system.
Section 9
Voltage protection
(Equation 92)
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