VT-SR11-1X/1/4WRD16-5X

The VT-SR11-1X/1/4WRD16-5X is an analog amplifier card produced by Bosch Rexroth Indramat for the VT-SWMA Modules series. The board conditions command signals and drives both coils of a 4WRD16 proportional directional valve, giving hydraulic actuators a precise flow relationship to a PLC reference. It plugs into a rack backplane and occupies a Eurocard slot, so it can be added to existing control racks to implement closed-loop pressure or speed regulation in industrial machines.

The module is powered from an operating supply of ±24 VDC; the design tolerates input excursions from ±22 VDC to ±28 VDC without losing regulation. Internal circuitry converts that supply into a stabilized output of ±15 V ±2% and makes up to 150 mA available for external sensors or reference sources. Overall current consumption stays below 150 mA, which reduces the load on the cabinet power supply. The printed circuit measures 100 × 160 mm and mates with a 32-pole male DIN 41612 D connector, providing a secure connection to the rack. A temperature-compensated oscillator runs at 5 kHz; this carrier frequency is mixed with the command input to generate a stable pulse-width output that the onboard power stage filters into the required analog coil current. The coil winding has a resistance of 700 Ω, helping the amplifier maintain controlled current delivery without oversaturating the valve.

A separate dither generator produces a ripple at 470 Hz that reduces spool stiction without disturbing system bandwidth. Relay logic on the board is energized by a nominal control line of +26 V; its gold-clad contacts have a switching time of less than 4 ms and are rated for a 0.5 A resistive load. When the relay closes, a calibrated flow path is enabled, and the amplifier can source or sink ±60 mA to the valve to match the rated flow curve of the 4WRD16 element.