ABB Relion 670 series, Technical Reference Manual

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19.2.13.2 Design
The Milliampere Input Module has six independent analog channels with separated
protection, filtering, reference, A/D-conversion and optical isolation for each input
making them galvanically isolated from each other and from the rest of the module.
For configuration of the input signals, refer to section "Signal matrix for mA inputs
SMMI" .
The analog inputs measure DC current in the range of +/- 20 mA. The A/D converter
has a digital filter with selectable filter frequency. All inputs are calibrated separately
The filter parameters and the calibration factors are stored in a non-volatile memory on
the module.
The calibration circuitry monitors the module temperature and starts an automatical
calibration procedure if the temperature drift is outside the allowed range. The module
communicates, like the other I/O-modules on the serial CAN-bus.
1MRK505222-UUS C
Section 19
IED hardware
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Technical reference manual