Specifications

• Manufacturer: Westinghouse (Emerson)

• Model: 3A99858G02 (QHS‑L 486 / 56ACE)

• Type: Combined Analog Input/Output Module (AI/AO)

• Architecture: Q‑Line (QHS‑L, left‑side slot)

• Channels: 4 isolated AI channels + 4 isolated AO channels

• Resolution: 12‑bit (both AI and AO)

• Input Ranges: 4–20 mA, 0–20 mA, 0–10 VDC (software/configurable)

• Output Ranges: 4–20 mA (default), 0–20 mA, 0–10 VDC (software/configurable via DIP switches)

• Isolation: 1000 Vrms channel‑to‑ground (all channels)

• Accuracy: ±0.1% of full scale at 25 °C (AI & AO)

• Operating Temperature: 0 °C to 60 °C

• Power Supply: 24 VDC ±10%, 7 W typical

• Form Factor: Standard Q‑Line card, rack‑mounted

• Status Indicators: LED for power, communication, and fault

• Compatibility: WDPF, Ovation DCS (legacy systems)

• Weight: Approx. 1.0 kg

Key Features

• Integrated I/O Design: Combines 4 AI + 4 AO channels in one slot, saving rack space and reducing wiring complexity.

• Left‑Slot Optimization: Designed for left‑side Q‑Line rack slots, compatible with legacy WDPF/Ovation configurations.

• Isolated Channels: 1000 Vrms isolation reduces electrical noise and crosstalk in harsh industrial environments.

• Field Configurability: Input/output ranges adjustable via DCS software or onboard DIP switches for flexible device compatibility.

• Diagnostic LEDs: Real‑time visual status for power, communication, and fault conditions to simplify troubleshooting.

• Legacy Reliability: Engineered for long‑term operation in critical infrastructure (power plants, refineries).

• Hot‑Swap Support: Online replacement without system shutdown for minimal downtime.

Applications

• Power generation (boiler/turbine control, plant auxiliary systems)

• Petrochemical refining and process automation

• Water/wastewater treatment plants

• Heavy manufacturing process control

• Legacy WDPF/Ovation system upgrades and replacements

Related Part Numbers

• 3A99858G01: QHS‑R 486 combined analog I/O (right‑slot)

• 3A99857G01: QHS‑R 486 analog output (right‑slot, 8‑channel)

• 3A99857G02: QHS‑L 486 analog output (left‑slot, 8‑channel)

• 3A99857G03: QHS‑R 486 analog output (right‑slot, latest revision)

• 3A99857G04: QHS‑L 486 analog output (left‑slot, latest revision)

Notes

• This is a legacy module, primarily used as a replacement/spare part for existing WDPF/Ovation installations.

• For new projects, Emerson recommends modern Ovation I/O modules for enhanced performance and diagnostics.