VT-SR7-1X/0/A4VS.500HS SO43A-1608

The VT-SR7-1X/0/A4VS.500HS SO43A-1608 is an electrohydraulic servo valve amplifier card produced by Bosch Rexroth Indramat for use in the VT-SWMA Modules series. Installed in a control rack, the card converts low-level command signals into controlled bidirectional currents for spool-type proportional valves used in industrial automation systems. By working with inductive position feedback and symmetrical power rails, the module regulates valve spool position so that hydraulic flow and pressure follow the reference signal with the accuracy required for closed-loop motion axes.

Built in the Eurocard format, the amplifier slides into a standard 100 mm × 160 mm slot and connects through a 32-pin DIN 41612 Form D header. Its analog circuitry is powered by dual supplies of ±24 VDC for the power stage and ±15 VDC for the signal paths, allowing separate filtering of high- and low-level rails. Because the output stage is push-pull bipolar, the board can drive either polarity of current without external relays, simplifying wiring to torque motors. No onboard voltage regulator is present, so the external source must remain within the required upper and lower limits.

The command input presents a resistance of 50 kΩ, minimizing loading on upstream controllers, while the enable gate is terminated at 700 Ω to ensure positive logic switching. An internal dither current of 3 mA at 340 Hz is superimposed on the spool current to reduce static friction and improve valve linearity. The closed-loop output can reach a maximum of ±60 mA, allowing the card to operate medium-sized two-stage servo valves. Inductive position feedback closes the loop without external converters. Acceptable bus variation ranges from ±28 V to ±22 V on the power rail and from ±15.2 V to ±14.8 V on the signal rail, keeping the analog stages within their operating window.