HAT833 Series Three Power ATS Controller User Manual Page 42 of 56
9.4
DEFINITE TIME DELAY AND INVERSE DEFINITE MINIMUM TIME SETTING
Definite Time:
overcurrent delay is definite time delay. Different overcurrent value has corresponding
delay.
Inverse Definite Minimum Time(IDMT):
overcurrent delay decrease with the increase of overcurrent.
Different overcurrent value has corresponding delay.
IDMT formula:
T = t / ((IA/IT)-1)
2
T: Overcurrent delay (second)
T: Timing multiplier ratio
IA: Current max. load current (L1/L2/L3)
IT: Overcurrent setting value
Example:
t = 36
IA = 550A
IT =500A
Conclusion: T = 3600s (1 hour)