ABB Relion 670 Series Applications Manual page 226

Section 9
Voltage protection
during faults. A metallic single-phase ground-fault causes the non-faulted phase voltages to
increase a factor of √3.
9.2.3.5 The following settings can be done for the two step overvoltage protection
ConnType : Sets whether the measurement shall be phase-to-ground fundamental value, phase-to-
phase fundamental value, phase-to-ground RMS value or phase-to-phase RMS value.
Operation : Disabled / Enabled .
VBase (given in GlobalBaseSel ): Base voltage phase to phase in primary kV. This voltage is used as
reference for voltage setting. OV2PTOV (59) measures selectively phase-to-ground voltages, or
phase-to-phase voltage chosen by the setting
gets lower than the set percentage of
the IED automatically divides set value for
RMS then set value for VBase is used. Therefore, always set VBase as rated primary phase-to-
phase ground voltage of the protected object. If phase to neutral (PhN) measurement is selected
as setting, the operation of phase-to-ground over voltage is automatically divided by sqrt3. This
means operation for phase-to-ground voltage over:
>
V (%)
EQUATION1713 V2 EN-US
and operation for phase-to-phase voltage over:
Vpickup
EQUATION1992-ANSI 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
applications it is sufficient that one phase voltage is high to give operation. If the function shall be
insensitive for single phase-to-ground faults
normally rise in the non-faulted phases at single phase-to-ground faults. In subtransmission and
transmission networks the UV function is mainly a system supervision function and 3 out of 3 is
selected.
Pickupn : Set pickup overvoltage operation value for step n , given as % of VBase . 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.
tResetn : Reset time for step n if definite time delay is used, given in s. The default value is 25 ms.
220
×
VBase kV ( ) / 3
> ×
(%) VBase(kV)
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ConnType . The function will operate if the voltage
VBase . When ConnType is set to PhN DFT or PhN RMS then
VBase by √3. When ConnType is set to PhPh DFT or PhPh
1 out of 3 , 2 out of 3 , 3 out of 3 . In most
1 out of 3 can be chosen, because the voltage will
1MRK 511 401-UUS F
M13852-22 v10
(Equation 96)
(Equation 97)
Bay control REC670
Application manual