ABB RELION 620 Series Technical Manual page 579

1MAC504801-IB E
620 series ANSI
Technical Manual
A071114 V3 EN
Figure 288: Trip Curves for a typical 12 kV, 630 A, 16 kA vacuum interrupter
Nr the number of closing-opening operations allowed for the circuit breaker
Ia the current at the time of tripping of the circuit breaker
Calculation of Directional Coef
The directional coefficient is calculated according to the formula:
Section 6
Supervision functions
573