Specifications of feed positioning system

• Accuracy of feed positioning system = 2 arc min. from the dish vertex
• Resolution = 1 arc min.
• Drive specifications :
  • Half Hp DC servo motor
    • Speed : 2000 RPM
    • Torque : 2.7 N-m
    • Operating Voltage : 55 Volts
    • Weight : 11kg
    • Inertia : 2.2 kg sqm X 10 ˆ (-3)
    • Thermal time constant: 23 min.
    • Electrical time constant : 2 milliseconds
    • Mechanical Time constant : 14.7 millisec.
    • Torque constant : 0.24 N-m/A
    • Inductance : 1.1 mH
    • Armature Resistance : 0.62 ohm
    • Peak current : 100 amp.
    • Voltage constant : 25V per 1000 rpm
  • Tachometer :
    • 4V/1000 rpm
    • Ripple : 1.5% at 400 rpm
    • Inertia : 8.4 X 10 ˆ (-5) kg-sqm
    • Weight : 0.32 Kg
  • Brake :
    • Holding torque : 13 N-m
    • Rated voltage to be applied for releasing brakes :24 VDC
    • Coil current : 1 Amp
• Feed Drive Controller :
  • Encoder : Incremental encoder with one arc min. resolution
  • Speed profile : Trapezoidal
  • Speed control : PWM technique at 10 KHz.
  • Power drive : 'H' Configuration using IRF150 MOSFETS.
  • PWM Generation : 8051FA microcontroller with non volatile memory to retain current position and enabling Liquid crystal display. Microcontroller communicates with Antenna Base Computer using RS-485 protocol with an asynchronous link.