ABB RELION REF615R, Technical Manual

Page: 254 / 664

used. If the Voltage selection setting is set to "phase-to-ground" or "phase-to-phase", the
Phase supervision setting is used for determining which phases or phase-to-phase
voltages ("A or AB", "B or BC" and "C or CA") and currents are to be used for the
calculation of the induced voltage.
Table 199: Voltages and currents used for induced voltage (emf) E calculation
Voltage selection setting Phase supervision
setting
Calculation of internal induced voltage (emf) E
1)
phase-to-ground A or AB
E V I j X
A A leak
= × + × ×
( )
3 ( )
GUID-B567E82F-DDAB-4D87-A209-097D5FC072C6 V2 EN
phase-to-ground B or BC
E V I j X
B B leak
= × + × ×
( )
3 ( )
GUID-551F8B8A-40D2-4D99-B20D-6FC433406EFF V2 EN
phase-to-ground C or CA
E V I j X
C C leak
= × + × ×
( )
3 ( )
GUID-8B274F07-54A0-4CEC-9AAC-618F742D9EED V2 EN
phase-to-phase A or AB
E V I I j X
AB A B leak
= + − × ×
( ) ( ) ( )
GUID-BA2D5CDB-BC06-4F7E-A71F-A2BEFC10F5A2 V2 EN
phase-to-phase B or BC
E V I I j X
BC B C leak
= + − × ×
( )
( ) ( )
GUID-AF78379A-78B9-466A-85E1-593333656FB8 V2 EN
phase-to-phase C or CA
E V I I j X
CA C A leak
= + − × ×
( )
( ) ( )
GUID-90521B6F-C9B3-411F-82AD-E5AAF3D3ACEA V2 EN
Pos sequence N/A
E V I j X
leak
= × + × ×
( )
3
1 1
( )
GUID-E79E33FD-02FF-4E92-80A4-C7FEBB99C839 V2 EN
1) Voltages, currents and the leakage reactance X
leak
in the calculations are given in volts, amps and ohms.
If all three phase or phase-to-phase voltages and phase currents are fed to
the protection relay, the positive-sequence alternative is recommended.
If the leakage reactance of the protected equipment is unknown or if the
measured voltage (V
m
) is to be used in the excitation level calculation,
then by setting the leakage reactance value to zero the calculated induced
voltage (E) is equal to the measured voltage.
The calculated V/f ratio is scaled to a value based on the nominal V
n
/f
n
ratio. However, the
highest allowed continuous voltage (in % V
n
) can be defined by setting the parameter
Voltage Max Cont to change the basis of the voltage. The measured voltage is compared
to the new base value to obtain the excitation level.
Section 4
1MRS240050-IB C
Protection functions
248 REF615R
Technical Manual