Technical difference between AQ-200 IED residual current channels Io1 and Io2
Every AQ-200 series IED equipped with current transformer module has two residual current channels Io1 and Io2. All protection and control functions that use residual current require the user to choose which of these two residual current channels is used. These two channels differ slightly in their performance. Main difference is the measurement range and inaccuracy of the measurement:
Io1 measurement range: 5 mA ... 150 A (RMS)
Io2 measurement range: 1 mA ... 75 A (RMS)
Io1 measurement inaccuracy:
0.002 ... 10.000 x In < ±0.5 % or < ±3 mA
10…150 × In < ±0.5 %
Io2 measurement inaccuracy:
0.002…25.000 × In < ±0.5 % or < ±0.6 mA
25…375 × In < ±1.0 %
In = Set nominal current of transformer.
As a rule of thumb you can consider Io1 as "coarse" residual current measurement which can measure really high currents and Io2 as "fine" residual current measurement which can measure very low currents with high accuracy. For other technical data please refer to IED manuals.