AI820 Differential Analog Input Module

Description

The AI820 Analog Input Module has 4 differential, bipolar current/voltage inputs. Each channel can be either a voltage or current input. The current inputs can withstand an accidental maximum normal mode 30 V d.c. connection. To protect the current input circuit against dangerous input levels, such as by accidentally connecting a 24 V source, the resistor rating of the 250Ω current sense resistors is about 5 Watts. This is intended only to temporarily protect one channel at a time.

The module distributes the external transmitter supply to each channel. This adds a simple connection (with extended MTUs) to distribute the supply to external 2 wire transmitters. There is no current limiting on the transmitter power terminals.

All 4 channels are isolated from the ModuleBus in one group. Power to the input stages is converted from the 24 V on the ModuleBus.

Features

• 4 channels for -20...+20 mA, 0...20 mA, 4...20 mA, -10...+10 V, 0...10 V, 2...10 V, -5...+5 V, 0...5 V, 1...5 V d.c. bipolar differential inputs.
• One group of 4 channels isolated from ground.
• 14 Bit resolution plus sign.
• Input shunt resistors protected to 30 V d.c.
• The input withstand HART communication.

Appendix A Specifications

AI820 Differential Analog Input Module, +/- 20 mA, +/- 10 V, +/- 5 V
3BSE020924-510 B 97

Four Different Types of MTUs

• The TU830 Extended MTU enables three-wire connection to the devices without additional terminals.
• The TU810 (or TU814) Compact MTU has terminals for 24 V process voltage inputs but requires external terminals for the distribution of 24 V power supply to the field devices.
• The TU812 Compact MTU has a D-Sub 25 pin (male) connector for connection to the process.

Technical Data

AI820 Differential Analog Input Module Specifications at 25°C

Feature: AI820 Analog Input Module
Number of Channels: 4
Type of Input: Bipolar differential
Measurement Ranges (Nominal): -20...+20 mA, 0...20 mA, 4...20 mA (1), -10...+10 V, 0...10 V, 2...10 V (1), -5...+5 V, 0...5 V, 1...5 V (1) d.c.
Over/Under Range: ± 15%
Input Impedance (at Voltage Input): 200kΩ ± 25% Common mode; 800kΩ ± 25% Normal mode
Input Impedance (at Current Input): 250 Ω
Maximum Field Cable Length: 600 meters (656 yd.)
Max. Differential d.c. Input (Fault): 30 V
Common Mode Voltage Input: 50 V d.c.
CMRR, 50 Hz, 60 Hz: 80 dB (>60 dB d.c.)
NMRR, 50 Hz, 60 Hz: 33 dB
Error: Max. 0.1%
Resolution: 14 bit plus sign
Temperature Drift, Current: Max. 50 ppm/°C
Temperature Drift, Voltage: Max. 70 ppm/°C
Update Cycle Time (All Four Channels): <26 ms
Current Consumption 24 V (Modulebus): 70 mA
Current Consumption 5 V (Modulebus): 80 mA
Power Dissipation: 1.7W
Voltage Supervision: Internal process supply
Input Filter (Rise Time): 40 ms
Fusing of Transmitter Supply on Extended MTU: Yes
Isolation: Groupwise isolated from ground
Module Termination Units: TU810, TU812, TU814, or TU830
MTU Keying Code: BB
Rated Insulation Voltage: 50 V
Dielectric Test Voltage: 500 V a.c