ABB RELION 670 SERIES REG670 - Page 455

Vo
V kV
kV
Max
Ph Ph
= = =
−
3
11
3
6 35.
ANSIEQUATION2394 V1 EN-US (Equation 237)
2. One VT input is to be used in the IED. The VT ratio should be set according to the
neutral point transformer ratio. For this application, the correct primary and
secondary rating values are 6.35 kV and 110 V respectively
.
3. For the base value, a generator-rated phase-to-phase voltage is to be set. Thus for
this application VBase=11 kV.
4. ROV2PTOV (59N) divides internally the set voltage base value with √3. Thus, the
internally used base is equal to the maximum Vo value. Therefore, if wanted
pickup is 5 percent from the neutral point, the ROV2PTOV (59N) pickup value is
set to Pickup1>=5%.
5. The definite time delay is set to 0.5 seconds.
ROV2PTOV (59N) application #2
ROV2PTOV (59N) is here connected to a three-phase voltage transformer set located
at generator HV terminal side.
1. Due to such connection, ROV2PTOV (59N) function calculates internally the 3Vo
voltage (that is, 3Vo=VA+VB+VC) at the HV terminals of the generator.
Maximum 3Vo voltage is present for a single phase-to-ground fault at the HV
terminal of the generator and it has the maximum primary value 3Vo
Max
:
3 3 3 11 19 05Vo V kV kV
Max Ph Ph
= ⋅ = ⋅ =
−
.
ANSIEQUATION2395 V1 EN-US (Equation 238)
2. Three VT inputs are to be used in the IED. The VT ratio should be set according to
the VT ratio. For this application, the correct primary and secondary VT rating
values are 11 kV and 1
10 V respectively.
3. For the base value, a generator-rated phase-to-phase voltage is to be set. Thus for
this application VBase=11 kV. This base voltage value is not set directly under the
function but it is instead selected by the Global Base Value parameter.
4. ROV2PTOV (59N) divides internally the set voltage base value with √3. Thus
internally used base voltage value is 6.35 kV. This is three times smaller than the
maximum 3Vo voltage. Therefore, if the wanted start is 5 percent from the neutral
point the ROV2PTOV (59N) pickup value is set to Pickup1=3·5 %=15 %(that is,
three times the desired coverage).
5. The definite time delay is set to 0.5 seconds.
ROV2PTOV (59N) application #3
ROV2PTOV (59N) is here connected to an open delta winding of the VT located at the
HV terminal side of the generator or the LV side of the unit transformer.
1MRK 502 071-UUS A Section 10
Voltage protection
Generator protection REG670 2.2 ANSI and Injection equipment REX060, REX061, REX062 449
Application manual