DIN Rail Power Supply Units: How the Service Lifetime Is Determined by The Temperature

MC DIN Rail Power Suply Unis How Service Lfe is Determined by Temperature 1 400x275

September 13, 2022

By Nadine Schinko, Assistant Marketing & Inside Sales, PULS

As a system engineer, it is important to have a reliable and long-lasting power supply on which you can rely. Failure of the unit after a short time is annoying, costly and time consuming.

Heat is the archenemy to long service life and reliability

The minimum lifetime of power supplies is determined by the lifetime of the electrolytic capacitors. The warmer it is, the faster the electrolytic capacitors dry out. Even a temperature rise of +10°C in the power supply cuts in half their service lifetime. To achieve the longest possible service lifetime for DIN rail power supplies, it is essential that the device is protected against overheating. The cooling concept in the power supply is an important factor for this. Ideally, the power supply is built in a way that prevents the unit from generating heat at all. In practice, however, the ideal case is not possible due to the power losses.

The PULS Cool design ensures a long service lifetime

MC DIN Rail Power Suply Unis How Service Lfe is Determined by Temperature 2 1087x989

Graphic 1: Cool Design = High Efficiency + Optimized Heat Dissipation + Precise Layout of Temperature-Sensitive Components

To ensure a long service lifetime of power supplies, the heat generation in the devices must be kept to a minimum. PULS defines “Cool Design” as the interaction of three essential points that lead to low heat generation:

Firstly, the consistently high efficiency, secondly, the optimized dissipation of heat losses to the surroundings of the device, and thirdly, the well-planned arrangement of temperature-sensitive components in the unit.

Higher efficiency means less heat

An essential factor for low heat generation in the power supply is high efficiency of the unit.

The efficiency value describes the ratio of output power to input power of a power supply. The difference is converted into heat as loss. The advantage of high efficiency is obvious on closer examination. The lower energy losses mean that not much heat is generated in the first place, thus reducing the amount of cooling required. As a result, the electrolytic capacitors achieve the service lifetime specified by the manufacturer. The reliability of the entire unit is also increased (see graphic 2).

MC DIN Rail Power Suply Unis How Service Lfe is Determined by Temperature 3 1920x443

Graphic 2: A high efficiency leads to less energy loss in the form of heat. This is reflected in a longer service lifetime of the power supply units, a smaller design and higher reliability

High full-load efficiencies make a small design possible

MC DIN Rail Power Suply Unis How Service Lfe is Determined by Temperature 4 1696x1200

Graphic 3: High efficiencies not only at full load, but across a wide load range (example CP20.241)

Due to the lower heat generation in the unit, heat sinks can be partially omitted (see graphic 2). However, partial load efficiencies are also becoming increasingly important in practice. Usually, power supplies are not operated permanently under full load. For the thermal design of control cabinets, therefore, the losses of the typical load must be considered (see graph 3 for the example CP20.241).The losses during no-load operation must also be considered. These should also be low so that they do not cause thermal stress in the control cabinet even in “standby mode”.The rule is: The higher the efficiency, the lower the power loss of a power supply in the form of heat.

Optimized heat dissipation is essential for a long service lifetime

Heat puts a strain on the service lifetime of components. In addition to high efficiency, another factor for a long service lifetime is a good cooling concept.

Despite high efficiency, a small amount of energy is always lost. PULS units have a very high efficiency of up to 95.6%. The remaining 4.4% of the input power is lost. The heat generated by the losses is unavoidable and must be dissipated directly to the surroundings. The outer surfaces of the housing and the convection air flow that passes through the unit serve this purpose. The convection air flow should be able to flow without obstruction between the components.In practice, however, this is difficult to achieve. Power supplies are becoming increasingly complex and smaller at the same time. Space inside the device is limited. This makes it even more important to install cooling ducts and consider them equal to the other components in the device. In addition to the installed cooling ducts, short and direct connections of the heat generators are also an option to keep as little heat as possible in the device. A smart cooling concept often eliminates the need for internal heat sinks. This benefits the low weight and also significantly reduces the cost of the power supply.

The right component arrangement is the key

The optimal arrangement of temperature-sensitive components is essential for long lifetime of units.

Circuit designers tend to optimize the arrangement of components according to electrical requirements. In doing so, they often compromise on thermal design. To ensure the longest possible service lifetime, life-determining components must be placed in the cooler areas. Temperature-sensitive components are primarily electrolytic capacitors, varistors and optocouplers. The electrolytic capacitors can be placed near the cool air flow.

MC DIN Rail Power Suply Unis How Service Lfe is Determined by Temperature 5 945x827

MC DIN Rail Power Suply Unis How Service Lfe is Determined by Temperature 6 945x827

Graphics 4 & 5: The practical test: A unit under a thermal imaging camera

Thermography can be used to prove that these measures contribute to a cool power supply. Thermography makes it possible to look inside DIN-rail power supplies. They are especially informative in the case of convection-cooled switched mode power supplies.

The practical test with a high-tech thermal imaging camera shows the hot spots in the device, the heat development in certain areas and the position of the components that heat up the most. Due to the “Cool Design”, the unit can develop its full potential under load without overheating.In convection cooling, the warm air is directed outwards by a flow. The effect of a functioning air flow can be proven by thermography.The shown thermographic image of a PULS CP10 clearly demonstrates that sensitive components, such as the electrolytic capacitors (image labels: 1, 2, 3, 4, 5), have been optimally placed and stay cool (see graph 4 + 5).

The PULS tip

The lower heat generation of a power supply protects all components installed in the control cabinet.

Lower losses not only ensure a longer power supply lifetime, but also a longer lifetime for all components installed in the control cabinet. Power supplies are typically a “hot spot” in control cabinets. For this specific reason, the maximum permissible temperatures are important for power supplies. Even if the control cabinet is specified at “only” 45°C, higher temperatures may well occur in the immediate vicinity of the power supply.A brief example:In a test setup, a DIMENSION CP10.241 power supply is placed in a box (3.15l volume) and loaded with 80% of the rated power. After 4h of operation, a temperature increase of approx. 19°C occurs in the box. If a device with only 6.7% lower efficiency were used (88.5% instead of 95.2%), the temperature increase in the control cabinet would be 35.3°C, that additional 16.3°C temperature increase would cut the service lifetime of the electrolytic capacitors more than half based on the 10°C rule.

PULS Logo 300x150

 

 

 

Source

Related Articles


Changing Scene

  • Andreas Sobotta to Assume Role of Vice President North and South America for Pilz Automation

    Andreas Sobotta to Assume Role of Vice President North and South America for Pilz Automation

    Pilz Automation Safety Canada L.P. announces that their long-term CEO and GM, Andreas Sobotta, will assume the role of Vice President North and South America, effective immediately. He will still work from the Canadian office in Mississauga and visit all other subsidiaries in North and South America. Pilz will take their time to find a… Read More…

  • SEW-Eurodrive: MAXOLUTION System Solutions

    SEW-Eurodrive: MAXOLUTION System Solutions

    Whether in production or logistics operations, MAXOLUTION is synonymous with innovation in factory automation – across all industries and worldwide – helping you achieve your vision of an adaptable and resilient lean smart factory. Under the MAXOLUTION brand, SEW-EURODRIVE creates customized solutions for cutting-edge materials handling technology – from the shop floor through to IT.… Read More…


Sponsored Content
The Easy Way to the Industrial IoT

The way to the Industrial IoT does not have to be complicated. Whether access to valuable data is required or new, data-driven services are to be generated, Weidmuller enables its customers to go from data to value the easy way. Weidmuller’s comprehensive and cutting-edge IIoT portfolio applies to greenfield and brownfield applications. Weidmuller offers components and solutions from data acquisition, data pre-processing, data communication and data analysis.

Visit Weidmuller’s Industrial IoT Portfolio.


ADVANCED Motion Controls Takes Servo Drives to New Heights (and Depths) with FlexPro Extended Environment Product Line

Advanced Motion Controls is proud to announce the addition of six new CANopen servo drives with Extended Environment capabilities to their FlexPro line. These new drives join AMC’s existing EtherCAT Extended Environment FlexPro drives, making the FlexPro line the go-to solution for motion control applications in harsh environments.

Many motion control applications take place in conditions that are less than ideal, such as extreme temperatures, high and low pressures, shocks and vibrations, and contamination. Electronics, including servo drives, can malfunction or sustain permanent damage in these conditions.

Read More


Service Wire Co. Announces New Titles for Key Executives

Bruce Kesler and Mark Gatewood have been given new titles and responsibilities for Service Wire Co.

Bruce Kesler has assumed the role of Senior Director – Business Development. Bruce will be responsible for Service Wire’s largest strategic accounts and our growing Strategic Accounts Team.

Mark Gatewood has been promoted to the role of Vice President – Sales & Marketing. In this role, Gatewood will lead the efforts of Service Wire Company’s entire sales and marketing organization in all market verticals.

Read More


Tri-Mach Announces the Purchase of an Additional 45,000 sq ft. Facility

Tri-Mach Elmira Facility

Recently, Tri-Mach Inc. was thrilled to announce the addition of a new 45,000 sq ft. facility. Located at 285 Union St., Elmira, ON, this facility expands Tri-Mach’s capabilities, allowing them to better serve the growing needs of their customers.

Positioning for growth, this additional facility will allow Tri-Mach to continue taking on large-scale projects, enhance product performance testing, and provide equipment storage for their customers. The building will also be the new home to their Skilled Trades Centre of Excellence.

Read More


JMP Parent Company, CONVERGIX Acquires AGR Automation, Expanding Global Reach

Convergix Automation Solutions has completed the acquisition of AGR Automation (“AGR”), a UK-based provider of custom, high-performance automation design and systems integration primarily to the life sciences industry.

Following Convergix’s acquisitions of JMP Solutions in August 2021 and Classic Design in February 2022, AGR marks the third investment in Crestview’s strategy to build Convergix into a diversified automation solutions provider targeting the global $500+ billion market, with a particular focus on the $70 billion global systems integration and connectivity segments. Financial terms of the transaction were not disclosed.

Read More


Latest Articles

  • Making the Sustainable Transformation of the Process Industry a Success

    Making the Sustainable Transformation of the Process Industry a Success

    By Krystie Johnston and Dr. Manfred Jagiella – Sustainability facilitates opportunity when approached with a mindset to preserve resources and promote circularity. We share one Earth, and it is our global responsibility to care for it for the next generation. Endress+Hauser is one global company that understands this responsibility – and practices it as well.… Read More…

  • Why NOARK’s 12VDC Shunt Trip Coils for MCCBs Make Power Systems Reliable and Safer

    Why NOARK’s 12VDC Shunt Trip Coils for MCCBs Make Power Systems Reliable and Safer

    Circuit breakers are an essential component of any modern electrical system. Designed to protect your home or business from potential overloads or short circuits, these devices are your first line of defense against electrical fires. There are, however, situations where remote tripping of the circuit breaker may be required. It could be for operational reasons,… Read More…