Overview
Configured for 4-20 mA signal acquisition in the ABB S800 I/O system, the ABB AI895 (AI895 Analog Input Module) provides eight intrinsically safe input channels with HART communication for two-wire transmitters and selected four-wire transmitter configurations.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | AI895 |
| Article Number | 3BSC690086R1 |
| Brand | ABB |
| Product Type | Analog Input Module |
| Series | S800 I/O |
| Signal Specification | 4-20 mA |
| Number of Channels | 8 |
| Signal Type | Unipolar single ended |
| HART | Yes |
| SOE | No |
| Redundancy | No |
| High Integrity | No |
| Intrinsic Safety | Yes |
| Resolution | 12 bit |
| Isolation | Groupwise isolated from ground |
| Under/Over Range | 1.5 / 22 mA |
| Accuracy Error | Typ. 0.05%, Max. 0.1% |
| Temperature Drift | Typ. 100 ppm/deg C |
| Input Filter Rise Time | 20 ms, 0-90% |
| CMRR | >80 dB at 50 Hz, 60 Hz |
| NMRR | >10 dB at 50 Hz, 60 Hz |
| Rated Insulation Voltage | 50 V |
| Dielectric Test Voltage | 500 V AC |
| Power Dissipation | 4.75 W |
| Modulebus Current | Typ. 130 mA at +5 V |
| External Supply Current | Typ. 270 mA, Max. <370 mA at +24 V |
| Transmitter Supply | At least 15 V at 20 mA loop current |
| Transmitter Supply Limit | 23 mA under overload |
| Current Input Voltage Drop | Typ. 3 V, PTC included |
| Compatible MTU | TU890, TU891, TU891Z |
| Keying Code | AE |
| Width | 45 mm |
| Depth | 102 mm; 111 mm including connector |
| Height | 119 mm |
| Weight | 0.2 kg |
| Operating Temperature | 0 to +55 deg C |
| Storage Temperature | -40 to +70 deg C |
| Relative Humidity | 5 to 95%, non-condensing |
| Protection Class | IP20 according to IEC 60529 |
| Corrosion Protection | ISA-S71.04: G3 |
| Pollution Degree | Degree 2, IEC 60664-1 |
| Mechanical Conditions | IEC/EN 61131-2 |
| EMC | EN 61000-6-4, EN 61000-6-2 |
| Electrical Safety | EN 61010-1, EN 61010-2-201 |
| Hazardous Area Certification | ATEX/IECEx Zone 2 with interface to Zone 0; cFMus C1 Div. 2/Zone 2 with interface to C1, C2, C3 Div. 1/Zone 0 |
| Marine Certification | ABS, BV, DNV, LR |
| CE Mark | Yes |
| RoHS | EU RoHS, UAE RoHS, CN RoHS |
| WEEE | Directive 2012/19/EU |
Intrinsic Safety and HART Signal Interface
The AI895 provides intrinsic safety protection components on every channel. Therefore, each channel can connect directly to Ex-certified process equipment in hazardous areas without additional external intrinsic safety devices.
Each channel supplies and monitors a two-wire 4-20 mA process transmitter while maintaining HART communication. The module also supports selected four-wire transmitter connections when wired according to the specified connection arrangement.
The transmitter supply provides at least 15 V at a 20 mA loop current. In addition, the built-in current limitation restricts the transmitter supply to 23 mA under overload conditions. The current input has a typical 3 V voltage drop, including the PTC.
The TU890 and TU891 Compact MTUs provide direct two-wire process connections without additional terminals. Use the TU890 for Ex applications, while the TU891 supports non-Ex applications. The TU891Z is also listed as compatible with the AI895.
The front LEDs indicate Fault, Run, Warning, and HART transmission status. Furthermore, the module supervises its internal process supply.
Frequently Asked Questions (FAQ)
Q: How many analog input channels does the ABB AI895 provide?
A: The AI895 provides 8 unipolar single-ended 4-20 mA analog input channels.
Q: Does the ABB AI895 support HART communication?
A: Yes. Each channel supports HART communication while powering and monitoring a two-wire process transmitter.
Q: Which MTUs are compatible with the ABB AI895?
A: The AI895 supports the TU890, TU891, and TU891Z Compact MTUs. The TU890 supports Ex applications, while the TU891 supports non-Ex applications.
Field Installation Guidelines
- Install the AI895 on the ABB S800 I/O platform using a compatible MTU.
- Select the TU890 when the installation requires the specified Ex interface.
- Use the TU891 for non-Ex installations and the TU891Z where the system configuration specifies it.
- Verify the transmitter loop wiring before energizing the channel.
- Maintain correct polarity for 4-20 mA two-wire transmitter connections.
- Keep analog signal wiring separated from high-current power and switching conductors to reduce electrical interference.
- Route HART-enabled signal wiring according to the plant’s approved instrumentation wiring practices.
- Connect cable shields according to the site’s grounding and EMC design. Avoid creating unintended ground loops.
- Confirm that the connected transmitter remains within the AI895 transmitter supply and loop-current limits.
- For four-wire transmitters, use only the connection arrangement specified for the AI895 so that HART communication remains available.
- Verify the MTU keying code and mechanical fit before inserting the module.
- Check the Fault, Run, Warning, and Tx LEDs after commissioning to confirm module and HART communication status.
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Contact: Manski Wong +86 18030205725 manski@cambia.cn
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