Yaskawa SRDA Series Servo Amplifier Modules

Technical Dossier

Product Details And Specifications

Yaskawa SRDA Series: Comprehensive Module Range and Technical Overview

The Yaskawa SRDA series servo amplifier platform is a core motion control component deployed across global heavy industry sectors, including petrochemical plants, nuclear power facilities, offshore oil refineries, steel mills, and large-scale automated manufacturing lines. The SRDA designation covers the digital servo drive amplifier modules engineered for Yaskawa's Sigma-II and Sigma-III servo motor families, providing closed-loop torque, velocity, and position control with high-resolution encoder feedback. These units are embedded in multi-axis machine tool controllers, robotic welding cells, and continuous process control systems where long operational lifecycles—often exceeding 15 years—are standard. The SRDA-SDA71A01A-1 is a representative unit within this catalog, rated for specific power and current output parameters aligned with Yaskawa's SDA motor frame class.

The Evolution of SRDA Architecture

The SRDA series emerged as Yaskawa transitioned from analog servo control (CACR/CPCR families) to fully digital drive platforms in the mid-1990s. Early SRDA units used proprietary serial encoder interfaces (Yaskawa's own 13-bit and 17-bit absolute encoder protocols) and communicated with host controllers via MECHATROLINK-I, a single-master synchronous fieldbus operating at 4 Mbps over RS-485 physical layer. As industrial networks evolved, MECHATROLINK-II (10 Mbps, multi-drop, up to 30 axes) became the dominant interface for SRDA-generation drives, enabling tighter synchronization across multi-axis gantry and Cartesian systems.

The SRDA architecture introduced on-board parameter storage via EEPROM, replacing the external parameter units (JUSP-OP) required by earlier SGDA/SGDB drives. Regenerative braking circuits were integrated directly into the amplifier module, reducing external resistor bank requirements for most standard inertia loads. The SDA sub-series (as in SRDA-SDA71A01A-1) corresponds to specific motor frame and power class pairings within the broader SRDA catalog. Compatibility constraints are significant: SRDA drives are not interchangeable with the later SGDV (Sigma-V) or SGDH (Sigma-II standalone) series without controller-side parameter and wiring modifications. Facilities running legacy Yaskawa MP-series or 21-series machine controllers must source original SRDA units or validated drop-in equivalents to maintain system integrity.

SRDA Full Catalog & Functionalities (SKU List)

The following SKUs represent verified models within the Yaskawa SRDA servo amplifier series, organized by functional classification. Each unit is a discrete servo power amplifier module unless otherwise noted.

Servo Power Amplifier Modules — SDA Sub-Series

• SRDA-SDA71A01A-1: Single-axis servo amplifier, SDA71 motor class, 200V AC input, MECHATROLINK-II interface, standard encoder feedback.
• SRDA-SDA71A01A-E: Export-variant of SDA71A01A-1; identical electrical spec, CE/UL marking differences.
• SRDA-SDA91A01A-1: Single-axis amplifier, SDA91 motor class, increased continuous output current rating over SDA71 frame.
• SRDA-SDA91A01A-E: Export-variant of SDA91A01A-1 with international compliance markings.
• SRDA-SDB71A01A-1: SDB sub-series, 71-frame motor pairing, revised regenerative circuit topology versus SDA sub-series.
• SRDA-SDB91A01A-1: SDB sub-series, 91-frame motor pairing, higher peak torque current capacity.
• SRDA-COA30A: Communication option card, MECHATROLINK-II add-on for base SRDA units without integrated fieldbus.
• SRDA-COA31A: Communication option card, DeviceNet interface for SRDA platform integration into Allen-Bradley or Omron network topologies.
• SRDA-EAA01A: Encoder adapter module, converts legacy 13-bit incremental encoder signals to SRDA-compatible serial format.
• SRDA-RGP01A: External regenerative resistor unit, for high-inertia load applications exceeding internal braking capacity of standard SRDA amplifiers.
• SRDA-SDA31A01A-1: Compact single-axis amplifier, SDA31 motor class, lower power range, suited for auxiliary axis control in multi-axis systems.
• SRDA-SDA51A01A-1: Mid-range single-axis amplifier, SDA51 motor class, bridging the power gap between SDA31 and SDA71 frames.
• SRDA-SDA131A01A-1: High-power single-axis amplifier, SDA131 motor class, for heavy-duty spindle or feed axis applications.
• SRDA-SDA201A01A-1: Extended power class amplifier, SDA201 motor frame, used in large-format machine tools and press line servo axes.
• SRDA-SDA301A01A-1: High-capacity amplifier, SDA301 motor class, deployed in heavy industrial servo applications requiring sustained high torque output.
• SRDA-PCB01A: Control PCB assembly, replacement board for SRDA amplifier chassis; used in board-level repair of failed amplifier units.
• SRDA-FAN01A: Cooling fan assembly, direct replacement for SRDA series amplifier thermal management units.

Sourcing Hard-to-Find & Obsolete SRDA Parts

The SRDA series has entered the mature-to-end-of-life phase of its product lifecycle. Yaskawa has formally discontinued new production of most SRDA amplifier variants, with official factory support limited or unavailable for many sub-models. This creates a critical sourcing challenge for facilities operating legacy machine tools, transfer lines, or process control systems built around SRDA-equipped servo axes.

DriveKNMS maintains a dedicated inventory of SRDA series units sourced through verified industrial surplus channels, decommissioned equipment recovery, and authorized distributor overstock. All units are cataloged by exact part number, hardware revision, and functional test status. For the SRDA-SDA71A01A-1 and related SDA/SDB sub-series models, DriveKNMS provides: direct unit supply for emergency breakdown replacement, cross-reference matching to identify compatible substitute models where exact units are unavailable, and technical consultation on parameter migration when transitioning from SRDA to Sigma-V (SGDV) or Sigma-7 (SGD7S) platforms. Long-term maintenance agreements are available for facilities requiring guaranteed stock reservation across multi-year service contracts.

Quality Control for the SRDA Range

SRDA series amplifiers present specific diagnostic challenges due to their integrated MECHATROLINK-II communication stack, multi-layer control PCB architecture, and dependency on Yaskawa-proprietary encoder protocols. DriveKNMS applies a structured test protocol to all SRDA units prior to shipment.

Each unit undergoes: visual inspection of power stage components (IGBT modules, DC bus capacitors, gate driver circuits) for physical degradation; functional power-on test under controlled load conditions to verify alarm-free initialization and encoder communication handshake; MECHATROLINK-II bus communication verification using protocol-level test equipment to confirm correct node addressing and data frame integrity; parameter read/write verification via Yaskawa SigmaWin+ or equivalent engineering software to confirm EEPROM integrity; and thermal cycling under rated load to identify latent failures in solder joints or capacitor ESR degradation. Units that do not pass all stages are quarantined and documented. Test records are available upon request for critical applications.