How to design effective power supply thermal management in industrial and medical systems
■ Models LEN120-24 and LEN120- 48 (24 and 48 V DC output, respectively) - From +50°C to +60°C, with a nominal 230 V AC input, output power derates 5%/°C
DIN is different The LEN120 series PSUs have a nominal power rating of 120 watts and are designed for standard DIN-rail mounting. For example, the LEN120-12 delivers an output of 12 V DC over nominal input voltage ranges of 90 to 264 V AC (universal) or 127 to 370 V DC ( Figure 8 ). When derating DIN-rail PSUs, the datasheets often simultaneously consider input and output voltages, in addition to the operating temperature. For the LEN120 series: ■ All models - From -20°C to -10°C, with a nominal 115 V AC input, output power derates 2%/°C - From -20°C to -10°C, with a nominal 230 V AC input, no derating is required - From +40°C to +60°C, with a nominal 115 V AC input, output power derates 2.5%/°C - For input voltages between 115 and 264 V AC and between 162 and 370 V DC , no derating is required - For input voltages between 115 and 90 V AC and between 162 and 127 V DC (low line conditions), output power derates 1%/V
Practical steps toward better thermal designs As shown, the integration of a PSU into a system involves complex thermal design issues. There are several practical steps designers can follow to help avoid unpleasant surprises: ■ The PSU maker can provide detailed information on the relationship between fan air flow and static pressure (the P-Q curve), enabling designers to know what airflow to expect if the PSU fan will be operating with or against internal back pressure in the system. ■ Some PSU makers can supply FlowTHERM thermal models of the PSU that can be used in the overall system model to assess PSU thermal performance and identify potential concerns. ■ Have the PSU maker review a system thermal design and make recommendations for further analysis, or confirm the validity of the design.
Conclusion
To help solve these issues, designers can turn to PSU designs from Bel Industrial Power that are optimized for different thermal environments and application scenarios. Additionally, thermal management tools are available from PSU makers that can help speed the design process.
There are several issues to consider when designing a PSU thermal management system for medical or industrial applications. They include system airflow, the impact that system fans can have on the performance of any fans integrated into the PSU, the specified operating temperature range, the need to support peak power delivery, and the impact the input voltage range can have on power dissipation.
Figure 8: The LEN120 series DIN-rail PSUs are rated 120 watts and are convection cooled. (Image source: Bel Power Solutions)
■ Model LEN120-12 (12 V DC output)
- From +45°C to +60°C, with a nominal 230 V AC input, output power derates 3.33%/°C
we get technical
32
33
Powered by FlippingBook