Basic Specifications

• Manufacturer: Emerson (Westinghouse)

• Model: 3A99795H25

• Type: Analog Output Module (AO)

• Channels: 8 isolated channels

• Resolution: 14‑bit

• Output Ranges: 4–20 mA (default), 0–10 VDC, ±5 VDC (software configurable)

• Isolation: 1500 Vrms channel‑to‑channel and channel‑to‑ground

• Accuracy: ±0.075% of full scale

• Operating Temperature: 0 °C to 65 °C

• Power Supply: 24 VDC ±10%, approx. 5.5 W

• Mounting: Standard DIN rail

• Certifications: CE, UL, cUL, EMC compliant

• Weight: 1.42 kg

Key Features

• High Precision: 14‑bit resolution for accurate closed‑loop control.

• Multi‑Range Support: Selectable mA/voltage outputs to match diverse actuators.

• High Isolation: 1500 Vrms isolation reduces EMI and crosstalk in harsh environments.

• Hot‑Swap: Online replacement without system shutdown.

• Comprehensive Diagnostics: LEDs (PWR/COMM/FAULT) plus status registers; detects open/short circuits and over‑range conditions.

• Software Configurable: Ranges, alarms, and fail‑safe values set via Ovation tools.

Installation & Wiring

• Mount on DIN rail; allow 50 mm clearance top and bottom for cooling.

• Use shielded twisted‑pair cables; follow Ovation analog wiring standards.

Troubleshooting

• No Output: Check 24 VDC power, wiring, and fuses.

• Communication Failure: Verify cables, termination resistors, and controller connection.

• Inaccurate Output: Check shielding, wiring integrity, and actuator calibration; confirm range match.

Difference between 3A99795H24 and 3A99795H25

• 3A99795H24: Early revision, widely deployed in legacy Ovation systems.

• 3A99795H25: Updated revision with minor firmware enhancements and component upgrades for improved long‑term reliability; fully compatible with H24 in form, fit, and function.