1. General Information

• Part Number: 0-51851 (51851)

• Manufacturer: Reliance Electric (now ABB/Baldor-Reliance)

• Product Type: PC Control Regulator Card (Drive Control Board)

• Application: Reliance FlexPak / CardPak DC Drive Systems

• Status: Discontinued; available as refurbished/used

• Mounting: Plug-in card, backplane edge connector

2. Electrical Specifications

• Power Supply: Drive internal control power (24 VDC logic)

• Control Dials (Front Plate): 4 rotary dials (0–10)

  • Min Speed

  • Max Speed

  • Current Limit

  • Accel Rate

• Potentiometers: 4 precision pots (rear of faceplate), 1:1 with dials

• On-Board Components: 3 toroidal transformers, 11 ceramic caps, transistors, ICs, resistors, diodes

• Signal Interface: Analog speed reference, current feedback, logic I/O

• Isolation: Basic signal isolation for industrial noise immunity

3. Key Functions

1. Speed Regulation: Sets min/max speed and acceleration ramps

2. Current Limiting: Adjustable current limit for motor protection

3. Drive Tuning: Calibrates speed and torque response via dials

4. Signal Processing: Conditions tach feedback and command signals

5. System Integration: Interfaces between operator panel and drive main control

4. Mechanical Characteristics

• Form Factor: Standard CardPak plug-in PCB

• Connection: Rear edge “tail” with conductive tabs (backplane connector)

• Faceplate Mount: 3 screws to front operator panel

• Dimensions: Standard drive card size (approx. 190×120×30 mm)

• Weight: ~0.45 kg

5. Environmental Ratings

• Operating Temp: 0°C to +55°C

• Storage Temp: -20°C to +70°C

• Humidity: 10%–90% RH, non-condensing

• Vibration: Industrial standard (10–100 Hz, 0.15 mm)

6. Installation

1. Power OFF: Disconnect all drive power

2. Access Slot: Open drive cabinet, locate CardPak slot

3. Insert Card: Align edge connector, seat firmly

4. Secure Faceplate: Fasten 3 screws to front panel

5. Set Dials: Adjust min/max speed, current limit, accel rate

6. Power ON: Test speed regulation and fault functions

7. Troubleshooting

• No Speed Control: Check dial settings, pot wiring, edge connector contact

• Motor Stalls: Verify current limit setting and on-board transformers

• Erratic Speed: Inspect tach feedback circuit and solder joints

• No Accel: Check accel rate dial and capacitor integrity

8. Compatibility

• Drives: Reliance FlexPak 3000, FlexPak Plus, CardPak chassis

• Replacements: Direct swap with 0-51851-5, 0-51851-6 (CRCG variant)

• Wiring: Same pinout as original; no program changes required