ABB Relion SMU615 Technical Manual page 171

1MRS758407 B
SMU615
Technical Manual
A071114 V3 EN
Figure 117: 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:
Condition monitoring functions
Section 6
165