Description

Product Overview

The Allen‑Bradley 1336-PB-SP2B is a precharge power control PCB spare board for Bulletin 1336 series variable frequency drives, designed to limit inrush current during drive power-up and safely charge the DC bus capacitors. It controls the precharge relay and resistor circuit, gradually building DC bus voltage before switching the main power path online, which protects the rectifier bridge and power semiconductors from damaging startup surges. This hardware resolves premature power component failure caused by large inrush spikes at power application, eliminating drive trips and blown fuses on medium-to-high horsepower VFD units. Plant maintenance technicians and automation integrators rely on this replacement board to restore power stage functionality on legacy Allen‑Bradley 1336 PLUS, PLUS II, IMPACT and FORCE drives. Onboard status LEDs provide quick visual indication of precharge sequence progress and fault conditions, speeding diagnosis of bus undervoltage or precharge timeout failures. Word count overview:174

Technical Specifications

• Product Model: 1336-PB-SP2B
• Brand: Allen‑Bradley
• Warranty: One Year
• Input Voltage: Derived from drive main AC input, 460 V AC class
• Operating Temperature: 0 °C to 60 °C
• Storage Temperature: -40 °C to 85 °C
• Response Time: Automatic timed precharge sequence, relay switching control
• Protection Class: IP20 (mounted internally inside drive enclosure)
• Accuracy Class: Not applicable (precharge power board)
• Output Frequency: Not applicable
• Rated Current Range: Matched for 60–600 HP 460V 1336 drive frames
• Communication Interface: Hardwired power and signal terminals to drive main control board
• Supported Protocols: Not applicable, analog voltage sampling and relay drive
• Overload Capacity: Precharge timeout protection, bus overvoltage / undervoltage detection
• Dimensions: PCB assembly sized for internal 1336 power section mounting
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Application Scenarios

• Large Fan VFD Power Stage Repair: This precharge board controls DC bus ramp-up for high horsepower industrial fan drives. The 1336-PB-SP2B suppresses initial inrush current, preventing rectifier damage during repeated power cycling of high-inertia fan systems.
• Centrifugal Pump Skid Drive Maintenance: Installed inside 1336 drive cabinets for large water and process pumps, the board manages controlled bus charging at startup. It reduces stress on bus capacitors and power components, extending service life for continuous-duty pump drives.
• Bulk Material Conveyor High-Power Drive Retrofit: The precharge circuit protects the VFD power stage when energizing heavy conveyor motors. Proper precharge sequence prevents nuisance fuse blowing and power supply faults during daily equipment startup cycles.