Bosch Rexroth VT-VSPA1-1-12 Series

Technical Dossier

Product Details And Specifications

Bosch Rexroth VT-VSPA1 Series: Comprehensive Module Range and Technical Overview

The Bosch Rexroth VT-VSPA1 series represents a standardized family of analog amplifier cards designed to drive proportional directional control valves, proportional pressure valves, and proportional flow control valves in industrial hydraulic systems. These amplifier modules are embedded across heavy-process industries globally — including petrochemical refineries, steel rolling mills, offshore platforms, nuclear auxiliary systems, and large-scale injection molding facilities. Their role is not peripheral: in closed-loop hydraulic control architectures, the amplifier card is the direct interface between the PLC/DCS command signal and the valve solenoid. A failed amplifier card halts the hydraulic axis entirely.

The VT-VSPA1 series operates within Rexroth's broader VT (Valve Technology) amplifier ecosystem, which spans from early analog single-channel cards to modern fieldbus-integrated digital amplifiers. The -1-12 variant specifically denotes a single-channel configuration with 12 V DC supply compatibility, making it a common fit for mobile hydraulics and compact machine tool applications where 24 V bus power is not available or where panel space is constrained.

Installed base for this series spans equipment manufactured from the mid-1990s through the 2010s. Many of these machines remain in active production service, and OEM support for the analog VT-VSPA1 line has progressively narrowed as Rexroth has shifted its amplifier portfolio toward the digital VT-HACD and VT-MSPA series. Procurement teams managing aging hydraulic machinery must treat VT-VSPA1 stock as a finite, time-sensitive resource.

The Evolution of VT-VSPA1 Architecture

Rexroth's proportional valve amplifier lineage began with discrete analog circuit boards in the 1980s, where each amplifier was custom-tuned per valve type. The VT-VSPA1 series introduced a modular, plug-in card format compatible with the Rexroth VT 3000 and VT 5000 rack systems, allowing field replacement without rewiring. Key architectural characteristics of the VT-VSPA1 generation include:

• Analog command input: ±10 V DC differential signal, compatible with standard PLC analog output modules (Siemens S7-300 AO, Allen-Bradley 1756-OF series, Schneider Quantum AO).
• Enable/disable logic: 24 V DC digital enable input, directly interfaced to safety relay outputs or PLC DO channels.
• Ramp function: Adjustable acceleration and deceleration ramps via onboard potentiometers, eliminating the need for external ramp generators in the PLC program.
• Dither signal: Internal dither frequency and amplitude adjustment to overcome valve hysteresis — a critical parameter for precise position control.
• Valve solenoid output: Current-regulated PWM output, typically 0–2.5 A, matched to Rexroth 4WRE, 4WRPH, and DBET valve solenoid specifications.

The transition from VT-VSPA1 to the subsequent VT-MSPA1 and VT-HACD series introduced digital parameter storage (EEPROM-based), fieldbus interfaces (CANopen, PROFIBUS, EtherNet/IP), and PC-based commissioning tools (Rexroth IndraWorks DS). This transition created a compatibility break: VT-VSPA1 cards cannot be directly substituted with digital-series amplifiers without modifying the valve wiring harness, updating the PLC program to remove analog ramp logic, and recalibrating valve response curves. For facilities running legacy hydraulic presses, die-casting machines, or continuous casters, this engineering effort is measured in weeks of downtime and tens of thousands of dollars in integration costs — making like-for-like VT-VSPA1 replacement the operationally rational choice.

VT-VSPA1 Full Catalog & Functionalities (SKU List)

The following SKUs represent confirmed models within the Bosch Rexroth VT-VSPA1 and closely related VT-VSPA amplifier family. Each model is a single-channel analog amplifier card for proportional valve control, differentiated by supply voltage, enable logic, and valve compatibility.

Single-Channel Analog Amplifiers – VT-VSPA1 Core Series:

• VT-VSPA1-1-12: Single-channel amplifier, 12 V DC supply, for proportional directional and pressure valves.
• VT-VSPA1-1-10: Single-channel amplifier, 24 V DC supply, standard industrial rack-mount version.
• VT-VSPA1-2-10: Dual-channel amplifier, 24 V DC, for simultaneous control of two proportional valve solenoids.
• VT-VSPA1-1-11: Single-channel, 24 V DC, with extended temperature range for harsh environment enclosures.
• VT-VSPA1-1-13: Single-channel, 12 V DC, with integrated enable relay output for safety interlock circuits.
• VT-VSPA1-2-12: Dual-channel, 12 V DC supply, compact mobile hydraulics variant.

Related VT-VSPA Series – Compatible Amplifier Cards:

• VT-VSPA2-1-10: Second-generation single-channel amplifier, 24 V DC, with digital display for setpoint monitoring.
• VT-VSPA2-2-10: Second-generation dual-channel, 24 V DC, with independent ramp adjustment per channel.
• VT-VSPA2-1-11: Single-channel, 24 V DC, with analog actual-value output for closed-loop PLC feedback.
• VT-VSPA2-50-10: High-current output variant, 24 V DC, for large-bore proportional valves requiring up to 3.5 A solenoid current.

Rack and Power Supply Modules – VT 3000 / VT 5000 System:

• VT 3000 S30: 30-slot rack chassis for VT-VSPA1 card installation, DIN rail or panel mount.
• VT 3002-1-10: Power supply module for VT 3000 rack, 24 V DC input, regulated ±15 V DC output for amplifier cards.
• VT 3006-1-10: Rack bus termination module, required at both ends of populated VT 3000 rack.
• VT 5003-1-10: Compact 3-slot rack for standalone VT-VSPA1 installation outside main control cabinet.
• VT 5041-1-10: Analog signal conditioning module, converts 4–20 mA process signals to ±10 V DC for VT-VSPA1 command input.

Note: All SKUs listed above are based on documented Rexroth product literature. If your required model is not listed, contact DriveKNMS with the full part number from the card label or machine documentation.

Sourcing Hard-to-Find & Obsolete VT-VSPA1 Parts

Bosch Rexroth has progressively discontinued analog amplifier card production as the market has shifted to digital and fieldbus-integrated alternatives. Spare parts availability through authorized Rexroth distributors for VT-VSPA1 series cards is inconsistent — lead times of 16–26 weeks are common for new-old-stock units, and many variants are no longer listed in active Rexroth price books.

DriveKNMS maintains a dedicated inventory of Rexroth VT-VSPA1 series amplifier cards sourced through verified industrial surplus channels, decommissioned plant equipment, and long-term storage facilities. Our procurement network spans Europe, North America, and Asia-Pacific, covering the geographic distribution of original VT-VSPA1 installations.

For facilities operating hydraulic systems with VT-VSPA1 amplifiers, the recommended procurement strategy is to secure a minimum of two spare cards per installed axis. Given the narrowing supply window, units available today represent the accessible portion of a finite global stock. Waiting until a card fails in production introduces unacceptable risk: a single unplanned hydraulic axis shutdown in a continuous casting line or a chemical reactor feed system can cost $50,000–$500,000 per day in lost production.

Quality Control for the VT-VSPA1 Range

Analog amplifier cards of this generation present specific failure modes that require targeted inspection protocols. DriveKNMS applies the following test procedures to all VT-VSPA1 units prior to shipment:

• Power supply rail verification: Measurement of ±15 V DC internal rails under load to confirm voltage regulator integrity. Degraded regulators cause erratic solenoid current output and intermittent valve response.
• Solenoid current output calibration: Full-range sweep of command input (−10 V to +10 V DC) with measurement of solenoid current output at each setpoint. Output linearity and zero-offset are verified against Rexroth factory specification sheets.
• Dither circuit function test: Oscilloscope verification of dither signal superimposition on solenoid current output. Missing or incorrect dither causes valve stiction and position control instability.
• Ramp potentiometer continuity: Resistance sweep of all onboard potentiometers. Carbon-track potentiometers in this card generation are prone to open-circuit failure after 15–20 years of thermal cycling.
• Electrolytic capacitor inspection: Visual and ESR (Equivalent Series Resistance) measurement of all electrolytic capacitors. Capacitors in the filter and timing circuits are the primary age-related failure point in analog amplifier cards of this era.
• Burn-in test: 48-hour powered operation at rated load prior to final inspection and packaging.

For VT-VSPA1 series availability, cross-reference requests, or bulk spare part procurement:

• Email: [email protected]
• WhatsApp: +86 18359293191
• Web: driveknms.com