847216-R is Reliance Electric BRCC1 field excitation control board exclusively designed for MaxPak & FlexPak series DC drive field winding excitation regulation system. Original OEM manufacturing discontinued, available via unused surplus inventory and fully bench-tested refurbished products only. It cooperates with main UCC1 control board (846723T) and SCR rectifier stack (846747-RB) to constitute complete DC drive control system, specially responsible for DC motor field coil constant current excitation regulation, field loss fault detection and field overcurrent protection, R suffix denotes revised upgraded PCB layout version with optimized surge suppression circuit.

847216: Base part number of standard BRCC1 field excitation regulator PCB for Reliance medium-power DC drive platform.R: Revised upgraded revision, updated component layout, improved anti-surge and EMC circuit compared to original non-revision base model, optimized thermal dissipation design for long-term continuous running.

Auxiliary control power input AC 110/120V 50/60Hz, allowable voltage deviation ±10%; field excitation output adjustable DC 0~230VDC, rated continuous output field current 18A, short-time 60s overload current up to 26A. PCB working ambient temperature range -10℃~+65℃, operating humidity 5%~93% non-condensing. Equipped with multi-turn adjustable potentiometers for field current setpoint, field loss trip threshold calibration; isolation withstand voltage between power circuit and control logic 2000Vrms, overall board dimension approx 218mm×146mm, net weight around 0.69kg.

Multiple pin terminal connectors distributed on PCB edge: large screw terminal group for auxiliary AC power input, field winding positive/negative output wiring; small pin plug terminals for interlock signal hardwire connection from main UCC1 control board and external field fault feedback wiring. No digital bus, RS485 or fieldbus communication interfaces; all control and feedback signals adopt discrete hardwire wired transmission only.

Receives enable interlock signal from main speed control board to activate field excitation loop, implements closed-loop constant current regulation for motor field winding via internal PWM/SCR phase control circuit to stabilize motor field flux under grid fluctuation and load variation. Real-time field current sampling monitoring to trigger field loss protection trip once field open-circuit or under-current occurs, sends interlock fault signal back to main control board to lock armature rectifier trigger output and shut down drive main power; built-in overcurrent cutoff protection for field winding overload damage prevention. Onboard potentiometers realize on-site field current rating and fault threshold parameter setting without external auxiliary equipment.

Matching with Reliance MaxPak Plus, FlexPak3000 series medium-power DC drive cabinets, paired with 846723T main control board and 846747-RB rectifier power stack; widely used for spare replacement of papermaking drying cylinder, metal wire drawing machine, rubber mixer DC drive field control board aging failure retrofit on traditional industrial production lines.

Cut off drive cabinet main AC power and auxiliary control supply, keep power-off for minimum 30 minutes to discharge internal filter capacitor residual high voltage before terminal disassembly and board removal for anti-electric-shock safety. Semi-annual routine maintenance: use dry low-pressure compressed air to clear PCB accumulated dust, strictly avoid corrosive cleaning solvent touching circuit copper trace and semiconductor devices. After board replacement, complete field current no-load calibration via onboard trim pots before full-load commissioning; store spare excitation control board in sealed anti-static constant temperature dry warehouse to prevent damp corrosion and electrostatic breakdown of onboard electronic components.