ABB Relion 611 Series, Technical Manual

Page: 449 / 536

The
OPERATE
output of the component is activated when the cumulative sum of the
integrator calculating the overcurrent 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 curve scaling is determined with the
Time multiplier setting.
There are two methods to level out the inverse-time characteristic.
• The Minimum operate time setting defines the minimum operating time for the
IDMT curve, that is, the operation time is always at least the Minimum operate
time setting.
• Alternatively, the IDMT Sat point is used for giving the leveling-out point as a
multiple of the Start value setting. (Global setting: Configuration/System/
IDMT Sat point ). The default parameter value is 50. This setting affects only the
overcurrent and earth-fault IDMT timers.
IDMT operation time at currents over 50 x In is not guaranteed.
1MRS757454 D
Section 9
General function block features
611 series 443
Technical Manual