1. General Information

• Model Number: 0-52807 (also 052807)

• Brand: RELIANCE Electric (ABB Baldor‑Reliance)

• Category: Industrial DC Drive Control Board / Plug‑in PCB Module

• Alias: VSSA (Voltage Speed Signal Adapter) Board, Speed Signal Conditioning Card, MaxPak Plus Spindle Drive Board

• Description: Rack‑mounted plug‑in printed circuit board with front‑panel calibration potentiometer and terminal strip; conformal coated for industrial environment

• Status: Obsolete (legacy OEM part; available as refurbished/used)

2. Function & Positioning

• Primary Function: Voltage & Speed Signal Adaptation/Isolation for Reliance MaxPak Plus DC spindle drives

• Core Functions:

  • Speed Signal Conditioning: Converts/isolates tachometer or encoder signals for speed loop regulation

  • Voltage Sensing: Conditions armature/field voltage feedback for drive regulation

  • Signal Isolation: Provides electrical isolation between low‑level signals and power stage

  • Calibration: Front‑panel pot for scaling speed/voltage feedback signals

• Positioning: Critical signal interface card in DC spindle drive systems; ensures accurate, noise‑immune speed/voltage feedback for stable motor control

3. Technical Specifications

3.1 Electrical

• Signal Input: Tachometer generator (AC), encoder (pulse), or DC voltage signals

• Input Voltage Range: 0–120 VAC (tach), 0–10 VDC (control)

• Output Signals: Isolated, conditioned speed/voltage signals to drive control logic

• Power Supply: 115/230 VAC (from drive internal supply)

• Power Consumption: ≤ 12 VA

• Isolation Voltage: 1500 VAC (input‑to‑output)

3.2 Environmental

• Operating Temperature: 0 °C to +55 °C

• Storage Temperature: −20 °C to +70 °C

• Relative Humidity: 5%–95% (non‑condensing)

• Protection: Conformal coated PCB (moisture/dust resistance)

3.3 Mechanical

• Form Factor: Standard 19” rack plug‑in card

• Dimensions (W×H×D): 120 mm × 220 mm × 30 mm

• Weight: ~1.2 kg (2.67 lb)

• Connector: Gold‑plated edge connector (backplane interface)

• Front Panel: 10‑position terminal strip, 1 calibration potentiometer, 2 locking screws

3.4 Performance

• Signal Bandwidth: DC to 10 kHz

• Gain Accuracy: ±1% (calibrated)

• Isolation Rejection: >60 dB @ 50/60 Hz

• Response Time: <1 ms (signal conditioning)

4. Compatible Drives & Applications

4.1 Compatible Drives

• Reliance MaxPak Plus DC Spindle Drives

• Reliance V‑Series DC Drives

• Reliance Legacy DC Motor Control Systems

4.2 Industrial Fields

• Machine Tools: CNC lathes, milling machines, spindle drives

• Metallurgy: Rolling mills, process line speed control

• Paper/Textile: Web processing, tension control

• Retrofit: Replacement for aging Reliance DC drive systems

5. Installation & Maintenance

• Mounting: Plug into drive backplane; secure with front‑panel screws

• Wiring: Connect tach/voltage signals to terminal strip; output to drive control

• Calibration: Adjust front‑panel pot for correct speed/voltage scaling

• Maintenance: Annual connector inspection; clean conformal coating; test signal integrity

6. Ordering Info

• Part Number: 0-52807

• Alternate P/N: 052807

• Replacement: Direct replacement for VSSA module in MaxPak Plus drives