Basic Specifications

• Manufacturer: Westinghouse (Emerson)

• Model: 3A99857G01 (also known as QHS‑R 486 / 56ACE)

• Type: Analog Output Module (AO)

• Architecture: Q‑Line (QHS‑R, right‑side slot)

• Channels: 8 isolated channels

• Resolution: 12‑bit

• Output Ranges: 4–20 mA (default), 0–20 mA, 0–10 VDC

• Isolation: 1000 Vrms channel‑to‑ground

• Accuracy: ±0.1% of full scale at 25 °C

• Operating Temperature: 0 °C to 60 °C

• Power Supply: 24 VDC ±10%, 6 W typical

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

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

• Compatibility: WDPF, Ovation DCS (legacy systems)

Key Features

• Legacy Compatibility: Designed for older Westinghouse WDPF and early Ovation systems.

• Isolated Channels: Reduces noise and crosstalk in harsh industrial environments.

• Field‑Configurable: Output ranges set via DCS software or onboard DIP switches.

• Diagnostic LEDs: Quick visual status for power, communication, and faults.

• Reliable Performance: Built for long‑term operation in power plants and process facilities.

Common Applications

• Power generation (boiler, turbine control)

• Petrochemical and refinery processes

• Water/wastewater treatment plants

• Manufacturing process control

Related Part Numbers

• 3A99857G02: QHS‑L 486 analog output (left‑side slot)

• 3A99857G04: QHS‑L 486 analog output (alternate revision)

• 3A99858G01: QHS‑R 486 combined analog input/output (QAO/QAI)

Notes

• This is a legacy module, often used as a replacement or spare part in existing installations.

• For new projects, Emerson recommends modern Ovation I/O modules (e.g., 3A99795H25).