Rexroth R900782310 (VT-VSPA1-2-1X/V0/0) is a German-manufactured analog Eurocard-format proportional amplifier, designed exclusively to drive Rexroth DBETX, DBEM series proportional pressure valves without LVDT position feedback. Adopting standard DIN 41494 Eurocard dimensions (100×160mm), it features a 48-pin DIN 41612 male multipoint connector for rack wiring integration. The unit runs on 24VDC supply (18–35VDC tolerance) with power consumption below 24VA, accepting dual standard command inputs: differential 0–10V voltage or 4–20mA current loop signals from PLC/DCS control systems. It integrates a clocked PWM power output stage for solenoid drive, independent adjustable up/down ramp generators, onboard potentiometers for gain, zero offset and characteristic curve correction, plus comprehensive hardware protection and self-diagnosis circuits. Conformal coated PCB ensures stable operation in industrial cabinets within 0°C~50°C operating temperature range, with built-in reverse polarity, over-temperature, solenoid short-circuit and wire-break detection functions, and a front-panel LED to display operational readiness and fault status.

• Dual standard analog command input: 0–10V differential voltage and 4–20mA current input for seamless connection with industrial controllers
• Clocked PWM power output stage to generate stable adjustable solenoid drive current for proportional pressure valves
• Independent ramp generator with separate adjustable rise/fall time (20ms to 5s) to eliminate hydraulic pressure impact and mechanical shock
• Onboard tuning potentiometers for zero offset (ZW), gain attenuation and pressure characteristic curve linearization calibration
• External ramp time override digital input to switch fast/slow ramp speed via external contact signal
• Complete solenoid fault diagnosis: real-time detection of solenoid wire break, coil short-circuit and open circuit with LED alarm indication
• Over-temperature protection: automatically cuts off power output when internal overheating occurs to avoid card burnout
• Reverse polarity protection for 24VDC power supply to prevent damage from reversed wiring
• Ready-operation digital output signal to feed working status back to upper control systems (PLC/DCS)
• Actual value signal output to transmit real-time solenoid current feedback for closed-loop monitoring

• Amplitude limit circuit to cap maximum command signal and avoid valve over-travel and hydraulic overload

• Heavy Machinery Manufacturing: Hydraulic pressure control for injection molding machines, die-casting equipment and metal stamping presses
• Steel & Metallurgical Plants: Furnace hydraulic clamping systems, rolling mill pressure regulating proportional valve control
• Hydraulic Test Benches: Precise pressure simulation and load control for hydraulic component performance testing
• Plastic Processing Industry: Injection molding machine clamping pressure and melt backpressure proportional adjustment
• Energy & Power Equipment: Hydraulic actuator pressure control for turbine auxiliary oil systems and boiler valve actuators
• Mobile Machinery R&D Labs: Proportional pressure control test stands for excavators, loaders and agricultural machinery

• Industrial Automation Retrofit: Spare replacement amplifier for legacy Rexroth proportional hydraulic control racks during equipment upgrades

• Q: The front H2 LED flashes continuously while the PLC outputs a normal command signal?      
  A: Flashing LED indicates solenoid circuit faults; check broken solenoid wiring, shorted coil terminals, or damaged proportional valve solenoid coil resistance (normal resistance: 5~30Ω).
• Q: LED is completely off and proportional valve has no response to command signals?      
  A: Common causes include missing 24VDC power supply, blown internal card fuse, reversed power wiring triggering reverse polarity protection, or internal over-temperature shutdown due to poor cabinet heat dissipation.
• Q: Can VT-VSPA1-2-1X/V0/0 control proportional flow or directional valves with LVDT feedback?      
  A: No, this amplifier is specially designed for pressure valves without position feedback; select VT-VSPA2 series amplifiers for flow/directional valves with LVDT closed-loop control.
• Q: Hydraulic pressure fluctuates severely and the system vibrates during operation?      
  A: Adjust ramp time potentiometers to extend up/down ramp duration, re-calibrate gain and zero offset parameters, separate signal cables from high-power hydraulic motor wiring to reduce electromagnetic interference.
• Q: Is hot swapping supported for this Eurocard amplifier while the control rack remains powered?      
  A: Hot swap is prohibited. Power off the 24VDC rack supply before removing or inserting the card to avoid short-circuit damage to backplane bus and accidental hydraulic pressure surges.
• Q: PLC sends stable 4–20mA signal but the output solenoid current drifts slowly?      
  A: Check loose current input terminal wiring, calibrate the zero offset potentiometer (ZW) on the front panel, and verify stable 24VDC power supply without voltage ripple.