Description
Key Technical Specifications
| Parameter | Value |
|---|---|
| Manufacturer | ABB |
| Type | AI895 |
| Product ID | 3BSC690089R1 |
| Product Family | S800 I/O |
| Product Type | Analog Input |
| Number of Channels | 8 |
| Signal | 4–20 mA |
| Input Type | Single-ended, non-polar |
| HART | Yes |
| Intrinsic Safety | Yes |
| Resolution | 12 bit |
| Input Filter | 20 ms, 0–90% rise time |
| Typical Accuracy Error | 0.05% |
| Maximum Accuracy Error | 0.1% |
| Temperature Drift | 100 ppm/°C typical |
| Under/Over Range | 1.5 / 22 mA |
| Input Voltage Drop | Approximately 3 V including PTC |
| Transmitter Supply | At least 15 V at 20 mA per channel |
| Channel Isolation | Groupwise isolated from ground; 1 group of 8 channels |
| CMRR | >80 dB at 50/60 Hz |
| NMRR | >10 dB at 50/60 Hz |
| Rated Insulation Voltage | 50 V |
| Dielectric Test | 500 VAC |
| Power Dissipation | 4.75 W |
| +5 V ModuleBus Consumption | 130 mA typical |
| +24 V External Consumption | 270 mA typical; <370 mA maximum |
| Diagnostics | Fault, Run, Warning, HART Tx LEDs |
| Operating Temperature | 0 to +55 °C |
| Storage Temperature | -40 to +70 °C |
| Relative Humidity | 5–95%, non-condensing |
| Protection Class | IP20 |
| Width | 45 mm |
| Depth | 102 mm; 111 mm including connector |
| Height | 119 mm |
| Weight | 0.2 kg |
| Mounting | S800 I/O MTU |
| Compatible MTUs | TU890, TU891, TU891Z |
| Keying Code | AE |
| Hazardous-Area Certifications | ATEX/IECEx Zone 2 interface to Zone 0; cFMus hazardous-location applications |
| Marine Certifications | ABS, BV, DNV, LR |
These values come directly from ABB’s current AI895 datasheet.
Product Introduction
ABB AI895 3BSC690089R1
The ABB AI895 3BSC690089R1 is an eight-channel S800 I/O analog input module for 4–20 mA process signals. It combines analog acquisition, an intrinsic-safety interface, transmitter power, and HART communication in one module. ABB specifies compatibility with TU890, TU891, and TU891Z MTUs.
The key advantage is field integration. For hazardous-area instrumentation, the AI895 can interface with appropriately certified field equipment without relying on a separate external safety barrier arrangement. Each channel supports transmitter power, while HART communication provides access to instrument information over the same current loop.
AI895 3BSC690089R1
Application Scenarios & Field Pitfalls
Engineering Pain Point
A common problem in process plants is having a perfectly healthy 4–20 mA transmitter but poor data at the DCS. With an AI895, the fault can sit in the transmitter loop, intrinsic-safety interface, process power, termination unit, or HART communication path. Replacing the I/O module first is often the wrong diagnostic step.
Typical Applications
- Oil & Gas — Pressure, flow, level, and temperature transmitters installed in hazardous areas.
- Petrochemical — 4–20 mA process measurement from refinery units and tank farms.
- Chemical Processing — Hazardous-area transmitters connected to S800 I/O and 800xA control systems.
- Power Generation — Fuel, chemical, auxiliary-process, and other instrumentation requiring Ex-compatible analog acquisition.
Technical Pitfalls to Avoid
- Do not confuse with a standard S800 analog input.
Its defining feature is the intrinsic-safety interface plus HART capability. The electrical and certification requirements are different from ordinary S800 AI modules. - Use the correct MTU.
ABB specifies TU890, TU891, or TU891Z for . Check the complete I/O assembly rather than treating the module as an independent device. - Do not assume channel-to-channel isolation.
ABB specifies one group of eight channels isolated from ground. That is not equivalent to eight individually isolated channels. - Check the transmitter power requirement.
Each channel can provide at least 15 V at 20 mA for suitable two-wire transmitters. Make sure the field instrument and loop resistance remain within the permitted operating range. - Do not treat HART as a separate physical network.
HART communication is carried over the analog current loop. If the 4–20 mA loop is poorly wired or incorrectly terminated, HART communication can also be affected. - Watch the input voltage drop.
ABB specifies approximately 3 V including the PTC. When working with long cable runs or low-voltage transmitters, include this drop in the loop-power calculation. - Do not confuse with AO895.
is an analog input module. AO895 is an analog output module with eight 4–20 mA outputs and HART. The two have different process functions. - Check hazardous-area certification as a complete system.
Having an with an Ex certification does not automatically make every connected transmitter, wiring arrangement, and installation acceptable. The complete intrinsic-safety loop must satisfy the applicable certification. - Respect the temperature limitation with compact MTUs.
ABB specifies +55 °C generally, but limits the maximum ambient temperature to 40 °C for vertical mounting in a compact MTU. Cabinet orientation matters. - Use the front diagnostics.
The provides Fault, Run, Warning, and HART communication indications. Check these before condemning the module.
Related Products
- ABB TU890 3BSC690075R1 — Compact MTU intended for intrinsic-safety applications. It provides the field termination and ModuleBus interface for compatible modules including .
- ABB TU891 — Compact MTU for non-intrinsic-safety applications. It shares the general compact MTU concept but the application certification differs from TU890.
- ABB TU891Z — Another compatible MTU option specifically listed by ABB for . Verify the exact installation requirements before substitution.
- ABB AI890 3BSC690071R1 — intrinsic-safety analog input module for 4–20 mA applications. It is in the same hazardous-area I/O family but has different hardware characteristics and should not be assumed interchangeable with .
- ABB AI893 — intrinsic-safety analog input module. It provides a related analog-input function but should be selected according to the required signal and hazardous-area application.
- ABB AO895 3BSC690087R1 — Eight-channel 4–20 mA analog output module with HART and intrinsic-safety functionality. It complements but performs the opposite signal direction.
- ABB DI890 — Eight-channel intrinsic-safety digital input module. Used for discrete field signals rather than continuous 4–20 mA process measurements.
- ABB DO890 — Intrinsic-safety digital output module. Suitable for discrete control outputs, not analog transmitter acquisition.
- — The modular I/O platform containing and its associated MTUs and communication interfaces. The exact controller/interface configuration determines how the module connects to the higher-level control system.
- ABB AC 800M — Common controller platform used with I/O installations. supplies process measurements to the control architecture through the I/O communication structure.
