Pepperl+Fuchs SCD2-STC-EX1 Upgrade Solution for SCD Series

Product Overview

Pepperl+Fuchs SCD2-STC-EX1 Upgrade Solution for SCD Series: Smooth Transition from Legacy IS Transmitter Power Supplies

The Pepperl+Fuchs SCD2-STC-EX1 is a dual-channel intrinsically safe (IS) transmitter power supply designed for hazardous-area process automation environments. As legacy SCD Series modules reach end-of-life or become increasingly difficult to source, facilities running older Pepperl+Fuchs SCD1-STC-EX1 single-channel units or early-generation SCD Series barriers face mounting pressure to modernize their field instrument power infrastructure without triggering a full system shutdown.

This product page is specifically structured to support engineers and procurement teams planning a controlled migration from discontinued or aging IS transmitter power supplies to the SCD2-STC-EX1, with full attention to wiring compatibility, DIN rail footprint, power budget, communication protocol continuity, and hazardous-area certification compliance.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful migration from legacy SCD Series IS barriers to the SCD2-STC-EX1 rarely involves a single module swap. In practice, field engineers encounter a cascade of interdependent components that must be evaluated and, in many cases, replaced or reconfigured in parallel.

In the field instrument loop, the SCD2-STC-EX1 interfaces directly with 4–20 mA transmitters such as pressure, temperature, and flow sensors wired from Zone 1 or Zone 0 hazardous areas. When the existing SCD1-STC-EX1 or older SCD-STC-EX variants are removed, the field wiring — typically 0.5 mm² to 1.5 mm² shielded twisted-pair IS cable — can be retained without modification, as the SCD2-STC-EX1 maintains the same terminal block pitch and IS entity parameters.

On the safe-side output, the SCD2-STC-EX1 feeds into the DCS or PLC analog input cards. If the host system is a Siemens S7-300 or S7-400 series PLC with SM 331 analog input modules, the 4–20 mA passive output of the SCD2-STC-EX1 is directly compatible without signal conditioning changes. Similarly, for facilities running Honeywell Experion PKS or Yokogawa CENTUM VP DCS platforms, the module’s HART-transparent architecture ensures that HART Device Description (DD) files and field device configurations remain intact through the migration.

Where the control cabinet uses a Pepperl+Fuchs KFD2-STC4-Ex1 or KFD2-STC4-Ex2 as the existing IS transmitter power supply in a K-System DIN rail arrangement, the SCD2-STC-EX1 can be installed in the same 35 mm DIN rail segment. The SCD Series uses a compact 12.5 mm module pitch, meaning a full 24-channel IS barrier rack can be consolidated from 24 single-channel KFD-type modules into 12 dual-channel SCD2-STC-EX1 units — a significant reduction in cabinet footprint and wiring complexity.

For facilities that also need to upgrade their power distribution infrastructure, the SCD2-STC-EX1 is compatible with Pepperl+Fuchs F2D0-PS24 or equivalent 24 V DC DIN rail power supplies. If the existing power supply is undersized for the expanded dual-channel load, a parallel redundant power supply module such as the Pepperl+Fuchs F2D0-PS24-2A should be evaluated during the retrofit planning phase.

In applications where HART communication is critical — for example, when using a Pepperl+Fuchs HiDMux2700 HART multiplexer or a third-party HART modem for remote device configuration — the SCD2-STC-EX1’s HART-transparent design ensures that HART signals pass through without attenuation or distortion, preserving full compatibility with existing HART-based asset management systems.

For installations that include Pepperl+Fuchs LB Remote I/O or FB Remote I/O systems in Zone 2 or safe-area marshalling cabinets, the SCD2-STC-EX1 can serve as the IS interface between the remote I/O analog input cards and Zone 1 field transmitters, maintaining the same system architecture without requiring changes to the remote I/O configuration or fieldbus segment addressing.

Finally, where signal isolation is required between the IS barrier output and the DCS analog input — particularly in older installations with ground loop issues — a Pepperl+Fuchs KFD2-UT2-Ex1 or equivalent signal isolator/repeater can be inserted between the SCD2-STC-EX1 safe-side output and the DCS input card, resolving common-mode interference without disrupting the IS certification boundary.

Retrofit Guidance FAQ

Q: Can I reuse existing field wiring when replacing SCD1-STC-EX1 with SCD2-STC-EX1?
A: Yes. The SCD2-STC-EX1 uses the same IS entity parameters and terminal block family as the SCD1-STC-EX1. Existing IS field cables, cable glands, and junction box terminations can be retained without modification, provided the cable parameters (capacitance, inductance) remain within the certified IS entity limits.

Q: Is the SCD2-STC-EX1 compatible with HART field devices?
A: Yes. The SCD2-STC-EX1 is HART-transparent, meaning HART signals superimposed on the 4–20 mA loop pass through without filtering or attenuation. Existing HART Device Descriptions and field device configurations are preserved through the migration.

Q: What programming changes are required in the PLC or DCS after replacement?
A: None, in most cases. The SCD2-STC-EX1 is a passive IS barrier — it does not alter the 4–20 mA signal range or introduce any offset. PLC/DCS analog input scaling, engineering unit conversion, and alarm setpoints remain unchanged.

Q: Does the dual-channel design affect installation space in the control cabinet?
A: The SCD2-STC-EX1 consolidates two IS channels into a single 12.5 mm wide module, effectively halving the DIN rail space required compared to two single-channel units. This is particularly beneficial in retrofit projects where cabinet space is constrained.

Q: What supply voltage is required, and is it compatible with existing 24 V DC bus bars?
A: The SCD2-STC-EX1 accepts 20–35 V DC, making it fully compatible with standard 24 V DC IS barrier power bus bars. No power supply changes are required in most existing installations.

Q: How is the SCD2-STC-EX1 commissioned after installation?
A: No software configuration is required. After physical installation and wiring, the module is operational immediately. Loop integrity can be verified using a standard HART communicator or 4–20 mA loop calibrator connected at the safe-side terminals.

Warranty Assurance

Every SCD2-STC-EX1 unit shipped by TOPNLMS is covered by a 12-month warranty from the date of delivery. Prior to dispatch, each module undergoes functional verification including supply voltage input range testing, output current linearity check across the 4–20 mA range, and IS entity parameter confirmation against the manufacturer’s datasheet.

In the event of a confirmed defect within the warranty period, TOPNLMS provides direct replacement support with priority dispatch to minimize field downtime. Our technical team is available to assist with pre-installation compatibility verification, wiring review, and post-installation commissioning queries.

All units are shipped in original or equivalent protective packaging with full traceability documentation. Express shipping options are available for urgent replacement requirements, with dispatch from Xiamen typically within 1–3 business days of order confirmation.

For procurement teams requiring batch quantities, consignment stock arrangements, or vendor qualification documentation, please contact our sales team directly.

Stock availability is updated in real time. Inquire for lead times on high-volume orders.