BERGER LAHR WDP5-118.051-00 Stepper Drive – WDP5 Series

BERGER LAHR WDP5-118.051-00 – Stepper Drive Module for Closed-Cabinet Motion Control Architectures

The WDP5-118.051-00 is a panel-mount stepper drive unit manufactured by BERGER LAHR, a motion division subsequently integrated into Schneider Electric’s industrial automation portfolio. Within a multi-axis control cabinet, this module occupies the power-stage layer between the motion controller and the stepper motor, translating step/direction command pulses into precisely regulated phase currents. Its role is deterministic: each incoming pulse increments the motor shaft by a fixed angular displacement, and the drive’s internal current-chopping circuitry maintains that position against load disturbance without encoder feedback. This open-loop architecture is appropriate for applications where load inertia is well-characterised, mechanical compliance is low, and the cost of a full servo loop cannot be justified.

The WDP5 platform was designed for European OEM machine builders during a period when stepper technology was transitioning from simple L/R drives to constant-current chopper topologies. The -118.051-00 variant designation encodes the motor current rating, supply voltage range, and firmware revision, making it a specific, non-interchangeable configuration within the broader WDP5 family. Engineers specifying replacement units must match this full part number to preserve original machine performance envelopes.

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Technical Parameters

Hardware Logical Analysis

Bipolar H-Bridge Output Stage and Current Chopping: The WDP5-118.051-00 employs a bipolar H-bridge topology for each motor phase. Four power transistors per phase switch the DC bus voltage across the winding at a fixed chopping frequency, typically in the 20–40 kHz range. A sense resistor in the low-side leg feeds back instantaneous phase current to a comparator, which terminates each PWM on-time when the current reaches the programmed peak threshold. This constant-current regulation ensures that motor torque remains proportional to the commanded current setpoint regardless of winding back-EMF variation across the speed range—a critical property for maintaining step accuracy at mid-range velocities where resonance risk is highest.

Micro-stepping DAC Architecture: Smooth velocity profiles in the WDP5 series are achieved by a digital-to-analogue converter that synthesises sinusoidal current waveforms across the two motor phases. Rather than switching phase current in binary full-step or half-step increments, the DAC interpolates intermediate current levels, subdividing each full electrical cycle into a programmable number of micro-steps. This reduces the angular displacement per pulse, lowers the mechanical excitation frequency at a given shaft speed, and attenuates the mid-frequency resonance band that is characteristic of two-phase stepper motors operating in full-step mode. The practical result is quieter operation and reduced vibration transmission into the machine structure.

EMC Design and Shielding Architecture: The WDP5 platform was designed to comply with the European EMC Directive when installed according to manufacturer guidelines. The high-frequency switching of the H-bridge generates conducted and radiated emissions; the drive mitigates this through an integrated input filter on the DC bus, careful PCB ground-plane partitioning between the power and logic domains, and shielded motor cable requirements documented in the installation manual. The logic supply is isolated from the power stage ground reference, preventing switching noise from coupling into the step/direction signal lines—a common failure mode in lower-cost drives that causes spurious step counts and position drift.

Thermal Management: The aluminium heatsink extrusion on the WDP5-118.051-00 is sized for continuous operation at rated current in a 40 °C ambient environment. Above this threshold, the drive requires either forced-air cooling or derating of the output current. The thermal interface between the power transistor packages and the heatsink uses a controlled-thickness thermal compound layer; field replacement of this compound during maintenance is recommended if the unit has accumulated significant operating hours, as compound degradation increases junction-to-case thermal resistance and accelerates transistor aging.

System Integration Benefits

• Drop-in Mechanical and Electrical Compatibility: The WDP5-118.051-00 preserves the original connector pinout, DIN-rail footprint, and parameter set of the WDP5 platform, enabling direct substitution in existing machine cabinets without rewiring or PLC parameter changes. Downtime during a maintenance swap is limited to the physical replacement interval.
• Deterministic Step Execution: The step/direction interface provides a hard real-time command path with no protocol overhead. Each rising edge on the step input produces exactly one micro-step increment, giving the upstream motion controller full deterministic authority over shaft position without relying on drive-internal trajectory generation.
• RS-485 Serial Diagnostics: The WDP5 serial interface allows a host controller or HMI to read drive status registers, including fault codes, temperature warnings, and current setpoint confirmation, without interrupting motion execution. This diagnostic transparency reduces unplanned downtime by enabling condition monitoring during production.
• Selectable Current Profiles for Standstill Reduction: The drive supports automatic current reduction at standstill, lowering phase current to a configurable percentage of the running setpoint when no step pulses are received for a programmable timeout period. This reduces motor and drive heating during idle intervals, extending component service life in duty-cycle applications.
• Compatibility with Standard PLC Step/Direction Outputs: The TTL-compatible step/direction input accepts signals from virtually any industrial PLC or motion controller with digital output modules, including Siemens S7, Allen-Bradley CompactLogix, and Mitsubishi iQ-R series, without level-shifting hardware.
• Stable Mid-Speed Torque via Constant-Current Regulation: Unlike voltage-mode drives, the constant-current chopper maintains rated torque across the operating speed range up to the corner frequency, providing predictable acceleration performance for applications with variable load inertia.
• Fault Output Signal for PLC Integration: A dedicated fault relay or open-collector output signals drive fault conditions to the PLC, enabling automated machine stop sequences and fault logging without polling the serial interface. This simplifies safety-related control logic implementation.
• Long-Term Spare Parts Availability: The WDP5 platform has an established aftermarket supply chain across Asia, Europe, and North America. Sourcing replacement units through verified channels such as siemensplc.com ensures access to tested stock with documented provenance, reducing the risk of counterfeit or degraded components entering the machine.

Quality Assurance & Global Logistics

Every BERGER LAHR WDP5-118.051-00 unit dispatched from our Xiamen, China facility undergoes a structured pre-shipment verification process. Visual inspection confirms the absence of physical damage, corrosion on terminal contacts, and integrity of the heatsink mounting hardware. A power-on functional test verifies drive initialisation, fault-free status register state, and correct response to step/direction command pulses. Firmware revision markings are documented and included in the shipment record.

Units are packaged in anti-static bags with desiccant sachets, enclosed in foam-lined cartons rated for international air and sea freight handling. Export documentation—commercial invoice, packing list, and HS code declaration—is prepared for each shipment to facilitate customs clearance in the destination country. Typical dispatch lead time for in-stock units is 1–3 business days from order confirmation. International air freight to major industrial hubs in Europe, Southeast Asia, and North America typically achieves delivery within 5–10 business days. All shipments are tracked end-to-end, with tracking numbers provided at dispatch.

A 12-month warranty covers manufacturing defects and functional failure under normal operating conditions. Dead-on-arrival claims are accepted within 14 days of confirmed delivery. Warranty service is handled directly by our technical team, with replacement units dispatched upon fault confirmation to minimise machine downtime.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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