ABB RELION Series, Technical Manual

Page: 751 / 804

11.3 Voltage based inverse definite minimum time
characteristics
11.3.1 IDMT curves for overvoltage protection
In inverse-time modes, the operate time depends on the momentary value of the
voltage, the higher the voltage, the faster the operate time. The operate time
calculation or integration starts immediately when the voltage exceeds the set value of
the
Start value setting and the
START
output is activated.
The
OPERATE
output of the component is activated when the cumulative sum of the
integrator calculating the overvoltage situation exceeds the value set by the inverse
time mode. The set value depends on the selected curve type and the setting values
used. The user determines the curve scaling with the
Time multiplier setting.
The Minimum operate time setting defines the minimum operate time for the IDMT
mode, that is, it is possible to limit the IDMT based operate time for not becoming too
short. For example:
1MRS758755 A
Section 11
General function block features
REC615 and RER615 745
Technical Manual