Programmable Inverse Time Curves; Inverse Time Setting Error Signal; Limitations - Allen-Bradley Rockwell Automation 857 User Manual

Inverse Time Setting Error Signal

The inverse time setting error signal will become active, if
interpolation with the given parameters is not possible. See "Inverse
Time Operation" for more details.

Limitations

The minimum definite time delay start latest, when the measured
value is twenty times the setting. However, there are limitations at
high setting values due to the measurement range. See "Inverse Time
Operation" for more details.

Programmable Inverse Time Curves

The [current, time] curve points are programmed only using
SetPointPS PC program. There are some rules for defining the curve
points:
•
Configuration must begin from the topmost line
•
Line order must be as follows: the smallest current (longest
operation time) on the top and the largest current (shortest
operation time) on the bottom
•
All unused lines (on the bottom) should be filled with [1.00
0.00s]
Here is an example configuration of curve points:
Table 3.54 – Curve Point Configurations
Point Current I/I
1 1.00
2 2.00
3 5.00
4 10.00
5 20.00
6 40.00
7 1.00
8 1.00
9 1.00
10 1.00
11 1.00
12 1.00
13 1.00
14 1.00
15 1.00
16 1.00
Protection Functions
Operation delay
pick-up
10.00 s
6.50 s
4.00 s
3.00 s
2.00 s
1.00 s
0.00 s
0.00 s
0.00 s
0.00 s
0.00 s
0.00 s
0.00 s
0.00 s
0.00 s
0.00 s
3-91
857-UM001A-EN-P – July 2009