Areva MiCOM P921, Technical Manual

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Technical Guide P92x/EN FT/E11
User Guide
MiCOM P921-P922-P923 Page 31/110
8.1.3 "2Vpp+Vr" configuration (2 “Phase-Phase” VTs + 1 residual VT)
The 2 line voltages Vab, Vbc and the residual voltage Vr are then measured by the
MiCOM relay.
The derived quantities are : positive and negative sequences voltages (V1 and V2,
only for MiCOM P922 and p923), and the Vca line voltage.
) VBC
) a 2 1 (
) 1 a (
VAB ( 3 / 1 1 V
+
-
+ - = with a = e j2
p
/3
) VBC
) a 2 1 (
) a 2 (
VAB ( 3 / 1 2 V
+
+
+ - =
) VBC VAB ( VCA + - =
The only protection mode, which is available in this configuration, is the "Phase-
Phase" mode.
8.1.4 "3Vpn+Vr" configuration (3 "Phase-Neutral" VTs + 1 residual VT)
The 3 phase voltages VA, VB, VC and the residual voltage Vr will be measured by the
MiCOM relay.
The derived quantities are : positive and negative sequences voltages (V1 and V2,
only for MiCOM P922 and p923).
) VC ² a VB a VA ( 3 / 1 1 V + + = with a = e j2
p
/3
) VC a VB ² a VA ( 3 / 1 2 V + + =
If the protection mode is “Phase-Phase”, the line voltages Vab, Vbc and Vca will be
used in the protection algorithms. These line voltages are derived from the formulas
below :
) VA VB ( VAB
- =
) VB VC ( VBC - =
) VC VA ( VCA
- =
Please refer to the chapter P92x/EN CO of this Technical Guide, in which all the
connection schemes are indicated.