Product Description:

The VT-VSPA1-1-1X-VT13281A-U141 proportional amplifier card is produced by Bosch Rexroth Indramat for the VT-VSPA Proportional Amplifiers series. Designed for insertion into a standardized 3U rack, the board conditions analog command signals and drives proportional solenoid valves used in industrial hydraulic controls. By converting low-level set-point voltages into regulated coil currents, the amplifier enables smooth, closed-loop adjustment of valve spools, allowing machinery PLCs to modulate pressure or flow without discrete stepping relays.

The board follows the Euro-Card mechanical scheme and occupies 100 x 160 mm of rack space; component modules sit on a 3 TE front width while the solder side extends 5.08 mm beyond the card edge. A 24 V DC supply energizes the analog control circuitry, and current draw must not exceed 1.8 A during peak solenoid actuation. Circuit protection is provided by a 2.5 A Slow-Blow fuse that clears prolonged overloads yet tolerates inrush. Command references enter through a 32-pole male multipoint connector, and the amplifier processes them with true analog modulation rather than pulse-width methods, maintaining continuous current loops for proportional response. A 128.4 mm front plate supports test points for quick oscilloscope access.

The input rails may vary between 22 V at the lower limit and 35 V at the upper limit without affecting set-point linearity, so the card can operate from battery-buffered supplies or unregulated plant buses. Even at the maximum 50 VA loading, thermal rise remains within layout allowances because of generous copper pours and strategic vent slots in the shield plate. Signal and power lines mate to the backplane through the DIN 41612 Design D pattern, locking the board securely against vibration while ensuring matched impedance along the edge fingers. Ramp generators and dither oscillators are built with discrete components, and response times can be adjusted with potentiometers on the component side.