It is an original ABB analog signal measuring board designed for UNITROL excitation system and AC800PEC medium voltage drive control rack, manufactured in Europe. The PCB is coated with three-proof conformal coating to prevent erosion from moisture, dust and corrosive gas inside control cabinet. With standard rack plug-in structure matching backplane bus, it works as front-end analog signal conditioning and acquisition unit between field instrument transformers and main controller. Original mass production has been stopped and products are only available as aftermarket spare parts for equipment maintenance and renovation projects.

3BHE is the unified fixed spare part prefix of ABB PCB spare parts for excitation and medium voltage drive control.024577 is exclusive internal hardware development serial number defined by ABB R&D department for UFC789AE01 hardware platform.R0101 stands for the first official mass-production hardware revision without subsequent circuit modification.UFC789AE01 is the corresponding commercial ordering model of the finished module.

Rated auxiliary working power DC24V±10%, typical power consumption ≤4.0W. Operating ambient temperature ranges from -25℃ to +70℃, storage temperature ranges from -40℃ to +85℃, relative humidity keeps 5%RH~95%RH under non-condensing environment. Optocoupler isolation is adopted between field wiring and internal control circuit with isolation withstand voltage up to 1200VAC, full-scale sampling precision of analog channel ≤0.2%FS. The module is IP20 rated for cabinet installation and complies with IEC61000 EMC anti-interference standard, net weight approx 0.35kg.

Rear gold-finger connector is plugged into rack backplane bus to transmit converted digital sampling data and fault signals to main control board. Front terminal blocks are reserved for external secondary wiring of voltage transformers and current transformers. Multiple onboard LED indicators display module power status and each channel abnormal alarm for on-site inspection. Only factory dedicated test pads are arranged on PCB for offline calibration, no independent external fieldbus communication port is configured.

Receive raw AC voltage and current signals from generator-side PT and CT, complete surge absorption, filtering and amplitude matching to restrain industrial interference. Convert processed analog signals into standard digital data and upload to master AVR controller for closed-loop excitation regulation calculation. Built-in full-channel self-diagnosis function detects input circuit open-circuit and short-circuit faults, automatically upload fault codes and mark faulty channel once abnormal condition is captured.

This board is installed inside UNITROL1000 and UNITROL6000 excitation cabinets for synchronous generator units of thermal power plants, hydropower stations, gas-fired and biomass power plants. It is also configured in control cabinet of large synchronous driving motors applied for cement rotary kiln, mine main ventilation fan and petrochemical high-pressure compressor equipment.

Cut off total cabinet input power before disassembly or periodic maintenance, keep power disconnected more than 30 minutes to fully discharge residual capacitor energy and avoid static damage to precision onboard chips. Complete quarterly maintenance by clearing dust on PCB surface and gold-finger contacts with dry soft brush, and tighten all external wiring terminals regularly. When control system prompts sampling abnormal or channel failure alarm, inspect external transformer wiring preferentially before module replacement. Unauthorized disassembly of original components and arbitrary circuit modification are strictly forbidden; replace complete new module after permanent hardware damage is verified via professional detection.