A reliable power supply is the backbone of any automation solution. The requirements are particularly high in industrial applications: Intelligent systems, compact control cabinets, higher ambient temperatures and ever shorter maintenance cycles place tight limits on conventional power supplies. Selection is increasingly driven by the overall system – including additional functions, service life and ease of installation.
Selection criteria for power supplies in factory automation
Selecting the right power supply for factory automation is crucial, directly impacting the reliability, efficiency and safety of the entire plant. Modern manufacturing environments place high requirements on power supplies, as they operate continuously and often under harsh conditions. Therefore, various technical and economic aspects must be carefully considered when making a selection to ensure trouble-free and cost-effective operation:
- Stable output voltage, even with fluctuating loads and harsh environmental conditions.
- Overload, overvoltage and short-circuit protection are essential for the longevity of the power supply and end devices.
- Efficiency exceeding 90% reduces energy losses and minimizes heat generation.
- DIN rail power supplies enable flexible expansion and easy maintenance.
- Compliance with standards like UL, CE and RoHS guarantees suitability for global industrial use.
- Modern power supplies offer remote monitoring and diagnostic functions to enhance plant availability.
- In addition to the sum of all consumers, a reserve of at least 25% should be planned.
- Particularly in the case of motors or actuators, the power supply must be able to handle short-term load peaks without being oversized.
- Temperature range, humidity, vibrations and dust exposure must be taken into account.
- Tool-free installation, compact design and easy diagnostics simplify installation and maintenance.
- Durable components and a high mean time between failures (MTBF > 80,000 hours) offer economic advantages.
It is evident that modern power supplies must do way more than simply deliver stable power to meet the demanding conditions of industrial environments.
In order to guarantee a permanently reliable supply, the thermal performance of power supplies must be considered during the design phase. Derating starts at ambient temperatures above 60 °C: The maximum available output power is reduced depending on the temperature and installation environment. For planners and control cabinet manufacturers, it is therefore essential to take derating characteristics into account, especially for high packing density or limited airflow.
Compact, powerful and ready for peak loads
The Racpro1 series is specifically designed to meet these requirements (Fig. 1). The tool-free push-in terminals in a 25° design ensure time-saving and maintenance-free integration on the DIN rail. The devices also offer a compact design (from 43 mm wide), active switch-on current limitation and a service life exceeding 80,000 hours at 40 °C under full load.
To minimize thermal power losses, the package design utilizes the chimney effect: Warm air rises through vertical channels and creates a draft of cooler air from below. This natural convection ensures effective heat dissipation without the need for fans and guarantees full performance of the devices at ambient temperatures up to 60 °C (Fig. 2).
In addition to the package design, the optimized printed circuit board (PCB) layout also contributes to thermal and electrical stability. Large copper areas for heat distribution, strategic placement of heat-generating components and airflow-optimized conductor routing ensure efficient passive cooling. This increases the service life of the components and reduces the probability of failure under full load.
Another advantage is the power reserves: In addition to continuous power at an ambient temperature of 60 °C, the devices enable an additional power output of 120% at a reduced ambient temperature of 45 °C and, at 60 °C, a power boost of 150% for five seconds – ideal for sudden load changes. The system is supplemented by 4-channel electronic fuses (e-Fuses), allowing users to monitor the 24 V circuits. With selective protection, individual consumers can be selectively shut down in the event of a fault, making sure that important consumers, such as controls, remain in operation. Diode circuits using MOSFET technology allow low-loss connection of multiple power supplies for the redundant supply of safety-critical systems or for enhanced power. Active switch-on current limitation also protects the contacts of the upstream circuit breakers. Table 1 shows a comparison of the Racpro1-T240, -T480 and -T960 models.
Table 1: Comparison of the three Racpro1 models
| Racpro1-T240 | Racpro1-T480 | Racpro1-T960 | |
| Width | 43 mm | 52 mm | 80 mm |
| Efficiency | Up to 94.1% | Up to 95.3% | Up to 97.1% |
| Functional characteristics | Active switch-on current limitation; 2-phase AC operation 2x350 V to 2x575 V | PFC > 0.9 and active switch-on current limitation; passive load distribution in parallel operation and LED load indicator | PFC > 0.9 and active switch-on current limitation; passive load distribution in parallel operation and LED load indicator |
| Weighting | 500 g | 800 g | 1140 g |
Summary and outlook
In modern factory automation, power supplies are no longer “passive” components but central system components. They must combine energy efficiency, operational reliability and ease of maintenance. Beyond supplying power, they increasingly handle diagnostics, protection and communication functions. To meet these requirements, today’s power supplies must not only be powerful and compact but also feature intelligent protection mechanisms and robust designs.
The power supplies of the Racpro1 series are designed for centralized and decentralized use in control cabinets or directly on the machine. Combined with electronic fuses, redundancy diodes and uninterruptible power supply (UPS) systems, they form a modular supply system that is fully DIN rail compatible and easy to integrate (Fig. 3). Rutronik supports the implementation of a future-proof power supply architecture from source to load with a comprehensive range of products, technical advice and system expertise.
For more information and a direct ordering option, please visit our e-commerce platform at www.rutronik24.com.
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