Page 207 - Practical Power System and Protective Relays Commissioning

Protection Relays Chapter | 18 207

FIGURE 18.5.8 30 degrees connection maximum torque angle at zero degree.

TABLE 18.5.3 30 Degrees Connection Zero Degrees Maximum Torque
Angle Connections
Relay Current Voltage
R I R V RB
Y I Y V YR
B I B V BY

Refer to Fig. 18.5.9 for directional relay connections and to Fig. 18.5.10
for a residual voltage connection.
The recommended MTA for directional relays is as follows:
Zero degree for resistance-earthed systems;
Forty five degrees for lag power factor distribution system solidly earthed;
Sixty degrees for lag power factor transmission systems solidly earthed.