GE Industrial Solutions Entellisys 5.0 User Manual User Manual
Page 63
Overcurrent protection
63
5
fault where (I
RMS
/C) is 4.0, the circuit breaker will trip according to the I
2
T curve. In this case the
system will initiate a trip after approximately 1.1 seconds. On a fault where (I
RMS
/C) is 10.0, the
system will not follow the I
2
T curve and will instead initiate a trip according to the constant-time
part of the trip curve (i.e., after 0.283 seconds). In this case, if the system followed the I
2
T curve,
the trip time would have been only 0.18 seconds.
Values:
• Disabled
• Enabled
• Max Slope
Max Slope
I
2
T Max Slope limits the slope for ST delay band settings, transitioning from the I
2
T slope to the
definite time at 10x. Above 10X, the I
2
T slope is typically no longer needed for selectivity with the
I
2
T slope of smaller downstream breakers or fuses. The truncated I
2
T slope maintains selectivity
while providing superior protection.
Figure 5-3
Typical
I
2
T Curves - Max slope vers normal I
2
T