ABB RELION REX640 Technical Manual page 1564

Section 9
Control functions
1558
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
BW
2
GUID-41413669-A24C-4D4F-BF90-413C289050FE V1 EN
U |U – U |, differential voltage
d m p
U Setting parameter
BW
T
t
=
B 1
( − )
2
GUID-E96B6870-1DF7-4B22-841E-7C5F9EB2C0BF 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 812.
1MRS759142 C
(Equation 345)
(Equation 346)
– U . If the
m p
REX640
Technical Manual