Standard Inverse-Time Characteristics - ABB RELION REX640 Technical Manual

Section 11
General function block features
11.2.1.1
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Figure 856: Example of how the inverse time characteristic is leveled out with
currents over 50 x In and the Setting Start value setting "2.5 x In". (the
IDMT Sat point setting is set to maximum and the Minimum operate
time setting is set to minimum).
The grey zone in Figure 856
current is outside the guaranteed measuring range. Also, the maximum measured
current of 50 x In gives the leveling-out point 50/2.5 = 20 x I/I>.

Standard inverse-time characteristics

For inverse-time operation, both IEC and ANSI/IEEE standardized inverse-time
characteristics are supported.
shows the behavior of the curve in case the measured
1MRS759142 C
REX640
Technical Manual