WINGREEN 03ZSTI2-00-501-R | Solid-State Relay Module | Obsolete Industrial Spare Parts

The 03ZSTI2-00-501-R is typically installed in the output section of a control panel, acting as an interface between a PLC’s low-power digital output and field devices requiring higher current or voltage isolation. It is commonly found in packaging machines, textile equipment, or older automation lines in Asia-Pacific regions. While not always a single point of failure, its malfunction can disable critical actuators—such as reject gates, clamping units, or alarm beacons—leading to partial or full line stoppage. Due to its generic function, system integrators sometimes daisy-chain multiple loads through one module, amplifying the impact of a single failure.

This module is generally robust but suffers from age-related wear in high-cycle applications. The most common failure mode is output-side semiconductor degradation, resulting in either “stuck ON” (shorted SSR) or “stuck OFF” (open circuit)—the former posing a safety risk if it energizes a device unintentionally. Thermal stress from inadequate heat dissipation in densely packed panels accelerates SSR wear. Additionally, the optical coupler on the input side can degrade over time, especially in high-humidity environments, leading to intermittent triggering or complete signal loss.
Preventive maintenance should include: checking for excessive heat during operation (indicative of internal resistance rise), verifying LED response matches PLC command, inspecting terminals for oxidation or loosening, and ensuring ambient temperature remains within -20°C to +60°C. Avoid overloading beyond 80% of rated current to prolong service life.

WINGREEN has not actively marketed the 03ZSTI2 series in global industrial channels for over a decade. The brand appears to have been absorbed or discontinued, with no official end-of-life documentation available. As a result, technical support, datasheets, and genuine replacements are extremely limited. Continued use relies on dwindling inventory from third-party brokers, increasing both cost and counterfeit risk.
Temporary mitigation includes cross-referencing with functionally equivalent SSR modules from established brands such as Phoenix Contact (e.g., PLC-RSC series), Omron (G3MC), or Weidmüller (RC family)—ensuring matching voltage, current, and physical footprint. In many cases, a direct replacement is feasible with minor terminal rewiring. For long-term reliability, upgrading the entire I/O subsystem to a modern modular platform (e.g., Siemens ET 200SP, Allen-Bradley 1734) is advisable, though this requires panel redesign and revalidation. Until then, maintaining a small buffer stock of verified working units is prudent.