Product Description:

The VT-VSPA2-1-1X-T1 is a plug-in proportional amplifier card manufactured by Bosch Rexroth Indramat as a member of the VT-VSPA Proportional Amplifiers series. The board is intended for rack-mounted control systems where it converts analog setpoints from PLCs into a regulated solenoid current that drives hydraulic proportional valves used in industrial automation racks. By performing this current regulation on the card, the host controller can issue simple voltage references while the amplifier handles coil linearization, dither, and overcurrent limiting needed on hydraulic axes.

This Eurocard module follows a physical outline of 100 × 160 mm and plugs into a 32-pin male DIN 41612 form D connector that routes power, command, and feedback lines to the backplane. The control electronics operate from a supply of 24 VDC delivered by the machine bus. Apparent power drawn from that bus is rated at <50 VA, keeping the thermal load on the cabinet low. Four primary channels accept setpoints of ±9 V through a 100 Ω load, while a fifth channel uses a ±6 V window for reduced-scale commands. The differential input stage presents 100 kΩ of resistance to minimize source loading and common-mode error. Internally, the power stage can deliver up to 2.5 A of controlled output current to the valve coil, giving the motion controller ample authority over spool position even under fluctuating hydraulic pressures.

Protective and signaling functions are integrated on the board. An in-line fuse rated at 3.15 AT guards the supply rail, and continuous consumption is rated at <2 A, so the fuse margin is maintained during normal duty cycles. The on-board enable circuit releases the output only when the control pin rises above 8.5 V, preventing inadvertent valve movement during boot or wiring faults. A miniature relay with a coil resistance of 2150 Ω energizes at 16.8 V to switch auxiliary feedback paths. Despite these features, the card weighs only 0.13 kg, which reduces load on edge connectors and card guides.