AI825 Galvanic Isolated Analog Input Module

Description

The AI825 Analog Input Module features 4 individually galvanic isolated, bipolar current/voltage inputs. Each channel can be either a voltage or current input. The module has a direct current input that can withstand up to 6.3 V and an over-voltage protected current input that can withstand up to +30 V d.c., with current limited by a PTC resistor. Power for the input stages is converted from the 24 V on the ModuleBus. Three different types of MTUs can be used: TU831 Extended MTU, TU811, or TU813 Compact MTU, with the TU813 Compact MTU featuring crimped snap-in connectors for process connection.

Features

• 4 channels individually galvanic isolated inputs for +20 mA, 0...20 mA, 4...20 mA, +10 V, 0...10 V, 2...10 V.
• 14 Bit resolution plus sign.
• Input shunt resistors protected to 30 V d.c.
• The input withstands HART communication.

Technical Data

General Specifications at 25°C

• Number of channels: 4
• Type of input: Galvanic isolated channel to channel, channel to ground
• Measurement ranges (nominal): -20...+20 mA, 0...20 mA, 4...20 mA, -10...+10 V, 0...10 V, 2...10 V d.c.
• Over/under range: ± 15%
• Input impedance at voltage input (I x U): 10 MΩ
• Input impedance at current input (I x I): 50 Ω
• Over voltage protected current input (I x IP): 50 Ω + 125 Ω
• Maximum field cable length: 600 meters (656 yd.)
• Max. Differential d.c. input (Fault):
  • Voltage input: 30 V
  • Over voltage protected current input: 30 V
  • Current input: 6.3 V
• CMRR, 50 Hz, 60 Hz: 120 dB
• NMRR: >40 dB at 50 Hz, >55 dB at 60 Hz
• Error: Max. 0.1%
• Resolution: 14 bit plus sign
• Temperature drift:
  • Max 57 ppm/°C (± 20 mA)
  • Max 34 ppm/°C (± 10 V)
  • Max 78 ppm/°C (0...20 mA)
  • Max 47 ppm/°C (0...10 V)

Electrical Specifications

• Update cycle time (all four channels): <10 ms
• Current consumption 24 V (Modulebus): Typ 90 mA, max 110 mA
• Current consumption 5 V (Modulebus): Typ 70 mA, max 100 mA
• Power dissipation: Typ 2.5 W, max 3.2 W
• Voltage supervision: Internal supplies
• Input filter (0 to 90%): 130 ms at current input, 115 ms at voltage input

Physical and Environmental Specifications

• Module termination units: TU811, TU813 or TU831
• MTU keying code: DA
• Rated insulation voltage: 250 V
• Dielectric test voltage:
  • Between channels: 1900 V d.c.
  • Channel to ground and MB24V: 3250 V d.c.
  • MB24V to ground: 720 V d.c.