At Powerbox we often get asked advice on selecting the right power supplies for an application. Whilst each and every application will have their own variables that need to be considered, the following General Rules may assist in this process:
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Oversize your power supply
Do not select the minimum rated power supply for your application. Use a power supply which is larger than necessary. This means that under normal conditions the power supply will be running at a fraction of the power it is capable of delivering. This ensures the power supply will run cooler, reducing stress on components and therefore ensuring a longer lifespan.
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Provide as much cooling as possible
Provide as much cooling as possible The cooler a power supply will run, the longer the lifetime of components. Higher temperatures cause dielectrics in electrolytics to boil off sooner, semi-conductor devices to deteriorate faster and transformer insulation to deteriorate at an accelerated rate. Generally, for every 10°C rise in ambient temperature, power supply life is halved. It is therefore extremely important to ensure appropriate cooling is provided for conduction (base-plate) cooled products.
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Seek units designed by reputable, experienced companies
Conservative design procedures (not designing to minimum tolerance), proper thermal design and suitable component tolerances must be employed to ensure reliability, ruggedness and long life.
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The cheapest price is not the least cost
You don’t get something for nothing. To reduce costs, certain manufacturers will use lower grade components which are rated for low
temperature use. This means they will fail earlier, leading to short life and unreliability. This coupled with lower quality design and manufacturing processes further degrades reliability.
