ABB RED615 Technical Manual page 750

Section 9
Control functions
744
IDMT type operation
The IDMT timer can be selected by setting Delay characteristic to "Inverse time".
The minimum time at the inverse time characteristic is limited to 1.0 second.
However, the minimum recommended setting of the control delay times T1 and T2
is 10 seconds when the definite time delay is used and 25 seconds when the inverse
time delay is used.
The inverse time function is defined by the equations:
U
d
B
=
( U / ) 2
BW
GUID-59DE8DA1-7C1D-41A2-98A8-48A91D061FFD V1 EN
U |U – U |, differential voltage
d m p
U Setting parameter
BW
T
=
t
( )
−
B 1
2
GUID-18A433AA-B4A7-4DA8-94B2-4FDF12A23FD1 V1 EN
T T1 or T2
The monitored data UD_CTL shows the differential voltage value U
value exceeds half of the Band width voltage setting and has a negative sign, a
raising pulse is issued. The UD_CTL monitored data can also be seen in the DT
timer mode.
The hysteresis approach is presented in
Band width voltage
Figure 397.
1YHT530004D05 D
(Equation 95)
(Equation 96)
– U . If the
m p
615 series
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