Yokogawa STA4S-00 S1 Retrofit-Ready Terminal Block for STA Series Control Systems
The Yokogawa STA4S-00 S1 is a screwless spring-cage terminal block engineered for seamless integration into existing STA Series control panel assemblies. Rated at 32A and 800V, this module is a direct retrofit candidate for aging or discontinued terminal block rows in DIN Rail-mounted control cabinets across process automation, power distribution, and field instrumentation panels. Whether you are replacing a failed unit, upgrading a legacy wiring harness, or standardizing terminal blocks across a multi-panel installation, the STA4S-00 S1 delivers the mechanical and electrical compatibility required for a low-risk, minimal-downtime changeover.
In retrofit and modernization projects, the STA4S-00 S1 is commonly deployed alongside Yokogawa STARDOM FCN/FCJ controllers, where field wiring termination must remain stable during controller migration. Engineers replacing older screw-type terminal blocks with spring-cage variants benefit from the tool-free conductor insertion of the STA4S-00 S1, which eliminates torque inconsistency and reduces re-termination errors during panel rewiring. The module is fully compatible with standard 35mm DIN Rail (EN 60715), allowing it to be installed directly into existing rail segments without modification to the cabinet structure.
Upgrade Compatibility Table
| Parameter | STA4S-00 S1 Specification | Retrofit Notes |
|---|---|---|
| Rated Current | 32A | Verify existing wire gauge supports 32A; upgrade if previously derated |
| Rated Voltage | 800V | Compatible with standard 690V AC industrial panel wiring |
| Connection Type | Screwless Spring-Cage | Replaces screw-type STA variants; no torque tool required |
| Mounting | 35mm DIN Rail (EN 60715) | Direct drop-in on existing rail; no rail replacement needed |
| Conductor Range | 0.2–10 mm² | Confirm conductor cross-section before re-termination |
| Communication Compatibility | Passive terminal (signal/power) | No protocol dependency; compatible with all field bus topologies |
| Replacement Recommendation | Direct substitute for STA4S series | Confirm pole count and color coding match existing row layout |
| Commissioning Focus | Spring-cage insertion force, conductor strip length | Use manufacturer-specified strip length (typically 8–10mm) |
| Warranty | 12 Months | Covered from date of shipment; includes DOA and early failure |
Retrofit Planning for Existing Automation Systems
Successful integration of the STA4S-00 S1 into a live or recently decommissioned control system requires a structured pre-installation review. Begin by auditing the existing terminal block row: confirm the number of poles, the current color-coding scheme (grey for signal, blue for neutral, yellow-green for PE), and the physical spacing between adjacent blocks. In many legacy panels, the STA Series terminal blocks are installed adjacent to Yokogawa STA4PE-00 protective earth terminals and STA4N-00 neutral blocks, which must remain in their original positions to preserve the wiring documentation and panel labeling integrity.
For panels that include Yokogawa CENTUM VP or CENTUM CS 3000 I/O marshalling cabinets, the STA4S-00 S1 is frequently used in the field terminal assembly (FTA) wiring zone, where analog input signals from transmitters and thermocouples are landed before routing to the I/O modules. In these applications, confirm that the terminal block row is electrically isolated from the I/O card backplane and that the FTA connector (such as the KS1 or KS2 type) remains undisturbed during the terminal block swap. If the panel also contains Yokogawa AAI141 or AAI543 analog input cards, verify that the field wiring polarity is preserved after re-termination.
In control cabinets that house Yokogawa UT series temperature controllers or YS series single-loop controllers, the STA4S-00 S1 is used to terminate thermocouple extension leads, RTD wiring, and 4–20mA control signals. During retrofit, pay close attention to the conductor insulation color and the loop number labeling on each terminal. Use the existing loop diagrams and P&ID references to verify each termination point before energizing the circuit. Where the panel includes a Yokogawa MW100 data acquisition module or a Darwin DAQ unit, ensure that the signal ground terminals are re-landed correctly to avoid common-mode noise issues after the terminal block replacement.
For projects involving communication protocol migration — for example, transitioning from RS-485 MODBUS RTU to PROFIBUS DP or HART — the STA4S-00 S1 provides a stable passive termination point for shielded twisted-pair cables. The spring-cage mechanism ensures consistent contact resistance across the cable shield drain wire, which is critical for maintaining signal integrity in long cable runs. In these scenarios, the terminal block row is often installed adjacent to Yokogawa YCB301 PROFIBUS communication modules or HART multiplexers, and the STA4S-00 S1 must be positioned to allow clean cable routing without sharp bends that could compromise the cable shield.
Downtime Control During System Migration
Minimizing production downtime during a terminal block retrofit requires careful sequencing of the changeover work. The recommended approach is to complete all pre-wiring preparation — stripping conductors, labeling cables, and staging replacement blocks — before taking the panel offline. Where the control system allows, use the Yokogawa CENTUM VP batch management or sequence function blocks to place the affected control loops in manual mode prior to disconnecting field wiring. This preserves the last known setpoint and output value in the controller memory, allowing a faster return to automatic control after the retrofit is complete.
For panels where a full shutdown is not feasible, consider a phased replacement strategy: replace terminal blocks in groups of four to eight poles per shift, re-terminating and verifying each group before proceeding to the next. Use a calibrated loop tester or a Yokogawa CA71 handheld calibrator to verify 4–20mA signal continuity at each terminal after re-termination. Document the as-found and as-left resistance readings for each terminal to support the post-retrofit commissioning record. Where the panel includes a Yokogawa FAST/TOOLS SCADA system, confirm that the historian tags associated with the affected loops remain in service throughout the phased replacement to maintain data continuity for process reporting.
After completing the terminal block replacement, perform a full point-to-point continuity check against the loop diagrams before restoring the panel to service. Verify that all spring-cage connections are fully seated by performing a gentle pull test on each conductor. Restore control loops to automatic mode in the reverse sequence of the shutdown, and monitor the process variables for at least 15 minutes to confirm stable operation before releasing the panel to operations.
Retrofit Support FAQ
Q: Is the STA4S-00 S1 a direct drop-in replacement for the STA4S-00 screw-type terminal block?
A: Yes. The STA4S-00 S1 shares the same mechanical footprint and DIN Rail mounting dimensions as the screw-type STA4S-00. The primary difference is the spring-cage connection mechanism, which eliminates the need for a screwdriver during conductor insertion. No modification to the DIN Rail or adjacent terminal blocks is required.
Q: What conductor preparation is required before installing the STA4S-00 S1?
A: Strip the conductor insulation to the manufacturer-specified length, typically 8–10mm. Ferrules are recommended for stranded conductors to ensure consistent contact and prevent individual strands from contacting adjacent terminals. Solid conductors can be inserted directly without ferrules.
Q: How is the STA4S-00 S1 tested before shipment?
A: Each unit undergoes electrical continuity and contact resistance verification prior to shipment. Units are supplied with a 12-month warranty covering manufacturing defects and early failure. A certificate of conformity is available upon request for quality-controlled procurement processes.
Q: Can the STA4S-00 S1 be used in ATEX or hazardous area panels?
A: The standard STA4S-00 S1 is rated for general industrial environments. For hazardous area applications, confirm the applicable zone classification and consult the Yokogawa product documentation to verify whether an Ex-rated variant is required for your installation.
© 2026 SMARTNEXMSK. All rights reserved.
Original Source: https://smartnexmsk.com
Contact: sales@smartnexmsk.com | +86 18259474341
