BHEL UN0661AV1 DVR Voltage Sampling Module (PN: 69203IV1AA)

1. Product Description

UN0661AV1 with part number 69203IV1AA is a VME single-slot DVR (Digital Voltage Regulator) PCB card manufactured by BHEL for DATATRONIC generator excitation and turbine control racks. It belongs to the UN066x series excitation control suite, paired with UN0660AV1 reference board, UN0662AV1 excitation current board and UN0610AV1 auxiliary power supply to implement full compound AVR dual closed-loop control. The suffix IV1AA is a factory hardware revision variant of the base UN0661AV1 model (alternative revision 69203GB1AA). This vertical plug-in board adopts full conformal coating on PCB to resist dust, moisture and corrosive flue gas in power plant cabinets. It supports simplex and triple redundant TMR safety architecture, powered by 24VDC rack backplane bus. The dark metal front panel integrates multi-channel LED status indicators and front test terminals for PT voltage calibration, dual metal ejector latches support hot-swap maintenance without full rack power shutdown. The rear high-density dual-row VME gold finger bus enables high-speed data exchange with DATATRONIC rack master CPU, complying with industrial EMC and power station safety standards. Net weight approx 430g.

2. Core Product Functions

• Generator PT secondary voltage sampling and signal conditioning, accurately measure synchronous generator terminal voltage in real time
• High-speed analog-to-digital conversion of voltage feedback signals, transmit processed voltage values to UN0660AV1 reference logic board for compound AVR calculation
• Overvoltage / undervoltage detection logic, trigger generator excitation protection trip when voltage exceeds preset safety thresholds
• PT circuit fault diagnosis: detect PT open-circuit, short-circuit, broken wiring and abnormal signal attenuation
• TMR redundant cross-voting: synchronize voltage sampling data with two identical UN0661AV1 modules to eliminate single-card measurement deviation
• Built-in high-voltage galvanic isolation between PT field wiring and low-voltage digital logic to suppress strong EMI interference from generator transformers and high-voltage switchgear
• Transmit real-time terminal voltage, fault codes and protection trip status to rack master CPU via VME backplane bus, upload trend logs and SOE alarm records to plant DCS monitoring system
• Hot-swap compatible design for redundant racks; faulty UN0661AV1 can be replaced online without interrupting generator voltage regulation operation

3. Application Scenarios

• Coal-fired thermal power plant steam turbine generator static excitation control cabinets
• Combined cycle gas turbine power plant compound AVR voltage-current regulation racks
• Large hydropower station synchronous generator triple redundant voltage control systems
• Refinery, petrochemical and offshore platform self-generation turbine excitation protection panels
• Heavy industry captive power plants equipped with BHEL DATATRONIC turbine & generator control systems

4. Common Troubleshooting & Typical Issues

• Persistent PT Signal Loss Fault Alarm

  Causes: Damaged PT secondary wiring, loose terminal block connections, burnt internal signal conditioning circuit on UN0661AV1. Solutions: Inspect cable continuity, retighten all field wiring terminals, test and replace faulty signal channels or the whole module.

• Generator Voltage Hunting & Unstable Fluctuation

  Causes: Mismatched PID tuning parameters among UN0660/661/662AV1 modules, unshielded PT signal cables, severe high-frequency EMI interference. Solutions: Synchronize compound AVR control parameters, install double-shielded twisted pair wiring and connect cable shielding to cabinet protective ground.

• TMR Voting Discrepancy Alarm in Triple Redundant Rack

  Causes: Uneven signal attenuation of three PT measurement loops, inconsistent calibration offsets of three UN0661AV1 cards. Solutions: Unify calibration parameters for all three DVR sampling modules, standardize field cable length and shielding specifications.

• Module FAIL LED Steady Red, Unrecognized by Rack Master CPU

  Causes: Oxidized dirty VME backplane gold fingers, unstable 24VDC rack DC power supply, corrupted on-board monitoring logic. Solutions: Clean PCB contact pins with anti-static lint-free cloth, stabilize rack power voltage, reload factory firmware or replace defective UN0661AV1 module.

• False Overvoltage / Undervoltage Protection Trips

  Causes: Incorrect voltage calibration offset on UN0661AV1, damaged isolation transformers causing signal distortion. Solutions: Recalibrate PT voltage sampling channels per factory manual, replace damaged isolation components or entire module.