Author:
Rutronik Elektronische Bauelemente GmbH
Date
11/20/2025
PDF
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Figure 1: Sequential start
Industrial automation systems are becoming increasingly complex. More intelligent controllers, networked sensors, and distributed subsystems demand not only a stable power supply, but also efficient, safe, and easily maintainable power distribution. Traditional power supply and protection concepts are reaching their limits: rising current densities, fluctuating loads, and shorter maintenance cycles require smarter solutions that combine performance, intelligence, and diagnostic capability.
While conventional fuses or circuit breakers are still common, they are often too rigid. They tend to react either too early or too late – especially during transient overloads such as motor or capacitive load inrush currents. When a fault occurs, entire supply branches may shut down, causing costly downtime. In safety-critical systems, this can even become hazardous.
The solution lies in the integration of intelligent power supplies and electronic protection devices. Combining RECOM’s RACPRO1 power supply series with the RACPRO1-4SP e-Fuse modules, available from Rutronik, creates a scalable, future-proof foundation for reliable 24 V industrial DC distribution.
The Next Generation of Power Supplies
Selecting the right power supply is essential for stable and efficient operation. Modern factory automation requires compact devices that can handle fluctuating loads, provide long lifetimes, and remain easy to maintain. RECOM’s RACPRO1 family was developed precisely for this purpose.
These DIN-rail power supplies feature:
Thermal management plays a key role. Instead of relying on active cooling, RECOM’s “chimney effect” design uses natural convection: internal components are arranged vertically to create two airflow channels. As warm air rises, cooler air is drawn in from below, ensuring effective passive cooling without fans. This allows full performance up to 60 °C ambient temperature and guarantees excellent reliability even in dense control cabinets.
Optimized PCB design further enhances performance. Large copper areas distribute heat evenly, while the strategic placement of heat-generating components ensures uniform temperature profiles. The result is a high mean time between failures (MTBF > 80,000 h) and low derating even under harsh industrial conditions.
Designed for Dynamic Loads
In automation, loads are rarely constant. Motors, actuators, and controllers demand short-term peak currents that can exceed nominal levels by a factor of two or more. The RACPRO1 power supplies are designed to handle these dynamic requirements with reserve capacity.
At 45 °C ambient temperature, the units can deliver 120 % continuous power, and even at 60 °C, a 150 % power boost for five seconds is available – ideal for motor starts or stepper load transients. This eliminates the need for oversizing and simplifies system design.
To further enhance reliability, multiple power supplies can be connected in parallel using low-loss MOSFET diode circuits, enabling redundant operation or higher combined output power. This ensures uninterrupted operation even if one unit fails, making the system suitable for safety-critical applications.
From Power Supply to Power System
Modern industrial plants require more than just stable voltage. They demand an integrated power ecosystem that provides protection, prioritization, and diagnostics. This is where the RACPRO1-4SP e-Fuse modules come in – perfectly complementing the RACPRO1 power supply series.
Each module integrates four independently controllable electronic fuse channels in a compact DIN-rail housing. Each channel can be configured individually in terms of current limit, response time, and fault behavior.
In normal operation, the module tolerates up to 150 % of the rated load for five seconds, allowing safe startup of capacitive or inductive loads. In the event of a sustained overload or short circuit, the affected channel disconnects within less than 100 ms, while all others continue operating – ensuring selective protection without compromising the rest of the system.
Prioritized and Sequential Load Control
A major advantage of electronic fuses is their ability to manage loads intelligently. When the system powers up, the RACPRO1-4SP activates its four outputs sequentially. This staged startup distributes inrush currents over time, reducing stress on the power supply and stabilizing the overall grid.
In case of a fault or undervoltage, shutdown occurs in reverse order: non-critical loads are disconnected first, while vital control systems remain powered as long as possible. This built-in prioritization logic eliminates the need for external controllers or PLC programming.
Diagnostics and Customizable Fault Response
Downtime in industrial plants is expensive. Therefore, diagnostic transparency is essential. The RACPRO1-4SP provides detailed, real-time fault and status feedback via color-coded LEDs and potential-free DC-OK outputs. The module clearly indicates whether each channel is within its current limit, near overload, or in a fault state.
Behavior in the event of faults can be configured via DIP switches:
An external reset input allows remote fault clearing through PLC or SCADA systems, enabling efficient troubleshooting and minimizing on-site intervention.
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Figure 2: Intelligent hiccup interval switching
Handling High-Capacitance Loads
Many electronic loads, such as DC-DC converters or motor drivers, exhibit large input capacitances. Conventional protection devices often struggle with these, either tripping unnecessarily or failing to start. The RACPRO1-4SP, however, can safely switch capacitive loads up to 20,000 µF thanks to its controlled soft-start ramp. Voltage rises smoothly and linearly, extending the service life of downstream components and ensuring stable startup even under full load conditions.
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Figure 3: Start-up ramp of the RECOM e-Fuse in comparison with a competitor's solution with a high-capacity load (20,000µF) and full load (5A). The competitor's solution does not start
System Integration and Scalability
Both the RACPRO1 power supplies and the e-Fuse modules are designed for modular scalability. Identical housing formats for 5 A and 10 A e-Fuse variants simplify layout changes, while paired inputs and outputs enable space-saving daisy-chain configurations.
Combined, they form a DIN-rail-compatible ecosystem:
Together, they enable intelligent power distribution from source to load – compact, efficient, and ready for the requirements of Industry 4.0.
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Figure 4: Simple daisy-chaining with the RECOM solution (top)
Synergy for Future-Proof Automation
The interaction between RACPRO1 power supplies and RACPRO1-4SP e-Fuses goes beyond simple protection. It represents a system approach to power reliability. The high efficiency and robust thermal design of the power supply ensure stable energy delivery, while the e-Fuses provide selective load control, fault isolation, and real-time diagnostics.
This synergy allows engineers to:
By combining intelligent supply and intelligent protection, RECOM and Rutronik deliver a solution that transforms traditional power distribution into a data-driven, self-protecting infrastructure.
Conclusion
As industrial systems evolve, the power supply chain itself becomes an active component of automation. Intelligent protection, thermal optimization, and digital diagnostics are no longer optional but essential. The RACPRO1 and RACPRO1-4SP families exemplify this transformation. They combine efficiency, reliability, and intelligence in a modular format designed for the next generation of factory automation. As a technology partner, Rutronik supports customers not only with access to these innovative RECOM products but also with comprehensive design-in support, system consulting, and logistics services — from prototype to mass production.
The result: a sustainable, future-ready power architecture that keeps industrial systems running safely, efficiently, and intelligently.
