The Foxboro FBMSVH control card is used for closed-loop control systems to control the valve position of pneumatic or hydraulic servos. It accepts input commands in the range of 4-20mA or 0-10VDC. Feedback input can be derived from an LVDT with a 0-10V signal. After processing the DEH command and LVDT feedback voltage using P or P+I regulation, it outputs ±27mA current to drive the servo valve. The module operates with an external ±15V power supply, which can be connected to the respective input terminals.

Key Features

• Selectable current or voltage input (DEH) with separately adjustable zero point and full-scale range using S2 switch.
• Equipped with an LVDT modulator and demodulator with adjustable amplitude and a driving current of 50mA.
• Can also output a 0-20mA valve position signal (impedance 50Ω).
• Allows for external shutdown contacts and adjustable proportional and integral control loops.

Technical Specifications

• Temperature:
  • Storage Temperature Range: -40°C to 70°C
  • Operating Temperature Range: 0°C to 50°C
• Power Supply:
  • Power Supply Voltage: ±15VDC
  • Voltage Regulation Accuracy: ±1%
  • Ripple/Noise: ±1%
  • Power Consumption:
    • +15V Power Supply: 250mA
    • -15V Power Supply: 250mA
• Command Input:
  • Input Impedance (Current Input): 500Ω
  • Input Impedance (Voltage Input): 4.3KΩ
  • Maximum Command Current: 21mA
  • Maximum Command Voltage: 11.0VDC
• Feedback (LVDT Feedback):
  • Demodulator Maximum Input: 18Vpp (6.36Vrms)
  • Oscillator Frequency:
    • Standard Value: 1000Hz
    • Error: 10%
• Feedback Circuit Adjustment Range:
  • Bias: Maximum (at G=1) -8VDC to 8VDC (adjustable)
  • Gain: Adjustable within the range of 1 to 20
• External Current Feedback (4-20mA):
  • Load Impedance (Current Input): 500Ω
  • Maximum Feedback Current Input: 21mA
• PI Control:
  • Proportional (Gain): Adjustable within the range of 0 to 20
  • Integral:
    • Integral Time Constant: Adjustable within the range of 1 to 20 seconds
• External Shutdown:
  • Closure of external contacts triggers shutdown with an output current of -10mA.
• Power Amplifier:
  • Output Current: Maximum ±30mA (80Ω)