Power Supplies and Switchgear in Industrial Control Systems: Sourcing SITOP, SIVACON, and Panel Hardware

PLC Direct
Power Supplies and Switchgear in Industrial Control Systems: Sourcing SITOP, SIVACON, and Panel Hardware

Table of Contents

    Industrial control panels contain several distinct hardware categories: power supplies, switching devices, soft starters, and panel instrumentation, each of which can cause a full system shutdown when it fails. For maintenance teams managing installed Siemens and Schneider Electric systems, sourcing verified replacements outside OEM channels is often the only practical option when lead times are long or product families have been discontinued. 

    This blog covers what each category of control panel hardware does, which product families are most commonly encountered in installed systems, and how facilities source surplus sealed and refurbished replacements. 

    What Hardware Lives Inside an Industrial Control Panel? 

    An industrial control panel contains four main hardware categories: power supplies, switching devices, soft starters, and panel instrumentation. Each serves a distinct function, and a failure in any one of them can take the control system offline. 

    • Power supplies convert incoming AC to the stable 24V DC that PLCs, I/O modules, HMIs, and safety relays require. Without a functioning power supply, none of the downstream control hardware operates. 

    • Switching devices and motor starters sit between the panel and the load. These manage motor starting, protecting against overloads, and isolating circuits during maintenance. These include contactors, motor starter protectors, overload relays, and soft starters. 

    • Panel instrumentation, such as power meters, provides visibility into load conditions, power quality, and energy consumption at the panel level. 

    • Switchgear enclosures and busbars define the physical infrastructure that houses and distributes power to connected loads. 

    When any of these components fail in an installed system, replacement decisions depend on what is actually stocked and available, not just what appears on the OEM price list. 

    What Is a SITOP Power Supply and What Does It Do? 

    A SITOP power supply converts incoming AC mains voltage to a regulated 24V DC output for industrial control hardware. It is Siemens' dedicated power supply range, designed to power SIMATIC PLCs, distributed I/O, HMIs, and other panel components. It is one of the most widely installed industrial power supply families in automation globally. 

    SITOP covers a broad performance range. Single-phase units like the SITOP PSU100S accept 120/230V AC input and deliver stable 24V DC at current ratings from 5A through 20A, a standard panel configuration across North American and international installations. DC/DC converter variants are suitable for applications where the input is already DC, common in battery-backed or 48V DC bus systems. 

    Beyond basic power supply, SITOP includes selectivity and redundancy modules for systems where power continuity is critical. The PSE200U selectivity module distributes 24V DC across multiple output channels with independent current limiting per branch, so a fault on one branch does not collapse the entire panel bus. The PSE202U redundancy module allows two SITOP supplies to operate in parallel with automatic decoupling, relevant in process environments where the panel cannot tolerate an unplanned outage. 

    For facilities running SIMATIC S7-300 or S7-400 systems, the installed SITOP units are often the same vintage as the PLCs, are discontinued or end-of-life by Siemens, but still require exact replacement when they fail. Surplus sealed and refurbished SITOP hardware across these families is available through PLC Direct, including discontinued series no longer available through standard OEM channels. 

    What SIRIUS Switching Devices Are Used in Industrial Control Panels? 

    SIRIUS is Siemens' family of switching and protection hardware for industrial control panels. It covers motor starter protectors, overload relays, motor starters, and soft starters, each serving a distinct function in panel motor control and circuit protection. 

    For facilities with SIRIUS devices installed, replacements must match the existing panel configuration: the same frame size, the same overload range, and the same auxiliary contact arrangement. 

    Confirmed SIRIUS product families available include: 

    • SIRIUS 3RV2 motor starter protectors combine the functions of a circuit breaker and an overload relay in a compact DIN-rail format. Available in frame sizes S00 through S3, covering overload current ranges from 10A through 50A and beyond. These units reduce the number of discrete protection components required in a panel. 

    • SIRIUS 3RM1 motor starters are compact electronic starters for smaller motor loads, with reversing starter configurations available for applications requiring bidirectional motor control. 

    • SIRIUS 3RW40 soft starters control motor acceleration and deceleration electronically, reducing mechanical stress on driven equipment and limiting inrush current during starting. Available across multiple frame sizes, covering motor ratings through 55kW at 400V and beyond. 

    • SIRIUS 3RB overload relays provide standalone motor protection for contactor-mounted applications, covering a wide current adjustment range with manual-automatic reset options. 

    For SIVACON switchgear enclosures, Siemens' low-voltage power distribution infrastructure used in substation and main distribution applications, contact us directly to discuss component availability. SIVACON hardware sourcing is assessed on a case-by-case basis depending on the specific panel configuration. 

    Browse the Siemens collection at PLC Direct for motor starter protectors, soft starters, and power supplies. 

    What Schneider Electric Hardware Is Used in Industrial Control Panels? 

    In Schneider Electric-based control panels, the most commonly replaced components are Altistart soft starters and PowerLogic power meters. These are mature, widely installed product families where OEM stocking depth is uneven and lead times can extend, making independent sourcing a practical alternative for maintenance teams. 

    • The Altistart 48 (ATS48) is one of the most widely installed soft starters in industrial panels across pump, fan, compressor, and conveyor applications. It connects directly to Modbus via RJ45 and interfaces with Ethernet, PROFIBUS DP, and DeviceNet through external modules. ATS48 units are available across a wide rating range, from smaller frames for motors rated up to 45kW at 400V through high-current configurations handling up to 500kW at 400V. For panels running ATS48 units, replacement options through standard distribution are often limited due to the product family's maturity. 

    • The Altistart 01 provides a compact DIN-rail-mounted option for smaller motor loads, three-phase motors up to 22A, in applications like conveyors, pumps, and fans where smooth starting is required without the complexity or cost of a full VFD installation. 

    • The PowerLogic PM8000 serves a different panel function: power quality metering and monitoring. These panel-mounted meters provide revenue-grade accuracy, multi-communication port support, and onboard power quality analysis. Facilities using PM8000 units for energy monitoring within control infrastructure may need replacements when a meter fails or when a panel is being upgraded, and the installed meter must be matched. 

    Browse the Schneider Electric collection at PLC Direct for Altistart soft starters and PowerLogic power meters. 

    How Do You Source Surplus Sealed and Refurbished Control Panel Hardware? 

    The right sourcing approach for industrial control panel hardware depends on the component type, the age of the installed system, and the urgency of the replacement. 

    • For discontinued SITOP and SIRIUS units, surplus sealed stock is often the only route to an exact SITOP PSU100S replacement or equivalent within the same series. Surplus sealed hardware is factory-sealed stock that has not been put into service; it retains its original condition but is no longer current production. This is particularly relevant for older SIMATIC S7-300-era panels, where the power supply and switching hardware are the same vintage as the PLC. 

    • For refurbished switchgear and soft starters, refurbished units have been tested and restored to operational condition. For components like the ATS48, where the failure mode is often a failed thyristor or control board rather than a mechanical failure, a refurbished unit from a supplier with a warranty offers a cost-effective path to restoring panel function without redesigning around a newer product. 

    • For active product families still in production with Siemens or Schneider Electric, such as the SITOP PSU100S or SIRIUS 3RW40 series, surplus sealed and refurbished stock provides an alternative when OEM lead times extend by weeks or months on high-demand items. 

    In Conclusion 

    Industrial control panels are built to run for decades, and the hardware inside them reflects that. SITOP power supplies, SIRIUS switching devices, and Altistart soft starters installed in the 1990s and 2000s are still running production lines today. The sourcing challenge isn't replacing the panel. It's finding the exact component, in a verified condition, without waiting weeks for an OEM order to clear. As an independent supplier, PLC Direct holds surplus sealed, refurbished, and used stock across Siemens and Schneider Electric panel hardware. These are available outside standard distribution timelines and with a 1-year warranty on every unit shipped. 

    PLC Direct

    With over 10 years in industrial automation hardware, the PLC Direct Team covers control systems, drives, HMIs, sensors, safety systems, and process instrumentation across a wide range of manufacturer lines. We support customers with parts lifecycle, hardware compatibility, procurement decisions, and maintenance challenges that arise in industrial automation environments.

    A surplus sealed SITOP power supply is factory-sealed stock that has never been installed or put into service. The unit is in its original sealed condition but may be older stock rather than current production. A refurbished SITOP unit has been previously installed, then tested, inspected, and restored to operational condition. Both are supplied with a 1-year PLC Direct warranty. The right choice depends on whether an exact original-condition unit is required or whether a verified operational replacement is sufficient.
    PLC Direct stocks SIRIUS switching devices, including 3RV2 motor starter protectors across frame sizes S00 through S3, 3RM1 reversing motor starters, 3RW40 soft starters in multiple current ratings, and 3RB overload relays. These are available as surplus sealed, refurbished, and used hardware. Contact PLC Direct with the specific part number to confirm current availability.
    For panels using Siemens SIRIUS switching devices, Schneider Altistart soft starters, or Schneider PowerLogic metering, PLC Direct supplies refurbished and surplus sealed replacements outside standard OEM distribution channels. This is particularly relevant for discontinued product families or active products with extended OEM lead times. Contact us with your part number to check availability.
    A soft starter controls motor acceleration and deceleration by ramping voltage during start and stop, reducing mechanical stress and inrush current. Once the motor reaches full speed, the soft starter bypasses, and the motor runs directly on line voltage. A variable frequency drive continuously controls motor speed throughout operation by varying both frequency and voltage. For applications where only starting and stopping control is needed. Conveyors, pumps, compressors, and a soft starter are simpler and lower-cost panel components than a VFD.
    The SITOP part number on the installed unit identifies the series, output current rating, and input voltage range. For SITOP PSU100S units, the suffix indicates the current output. The 6EP1336-2BA10, for example, is a 20A unit with 120/230V AC input and 24V DC output. Cross-reference the part number against panel documentation or the label on the installed unit before ordering, then contact PLC Direct with the full part number to confirm availability and condition grades in stock.