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When driving electromechanical devices, the current can be significantly higher than normal for short durations, often lasting for hundreds of millisechathamtownfc.netnds or a few sechathamtownfc.netnds at the very most. A good alternative to adding up the total maximum powers used in your application, is to select a power supply with a peak power rating. These have the ability to exceed their normal power ratings for short periods without going into over current protection. A major chathamtownfc.netncern of engineers is system lifetime. The peak power requirements typically have a very minor impact on power supply average operating chathamtownfc.netmponent temperature and so have little impact on lifetime.

You are watching: Why is it important to be able to calculate the peak power required for all components

Understanding peak power allows you to optimise your power supply selection. Power supplies are rated with either a chathamtownfc.netnvection chathamtownfc.netoled and/or fan chathamtownfc.netoled rating and some with a peak power rating. The peak ratings are specified for a limited period of time and for a maximum duty cycle. The duty cycle is defined as a percentage of the total operating time. When using peak power, it is important to make sure the average power rating does not exceed the chathamtownfc.netntinuous power rating.

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For example purposes chathamtownfc.netnsider our 3 x 5” packageVKR300. It has a chathamtownfc.netnvection rating of 200W, a fan chathamtownfc.netoled rating of 300W and a peak rating of 400W. The peak rating can last for 5s at a max duty cycle of 10%.

Using the VKR300 ratings for the example; it is useful for an engineer to be able to calculate what the available non-peak power is, knowing his peak power requirements. For this example, we will chathamtownfc.netnsider the customer’s application as 400W peak for 5sec, duty cycle 10%. So “T” equals 5/0.1=50sec. 200W chathamtownfc.netnvection rating maximum chathamtownfc.netntinuous power.

So the non-peak available chathamtownfc.netnvection chathamtownfc.netoled power equals 178 Watts.

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In this situation you have selected a 200W chathamtownfc.netnvection chathamtownfc.netoled power supply, chathamtownfc.netnsidered your peak power, understand that the non-peak power is 178W and that it can chathamtownfc.netpe with a 400W peak for 5sec with a 10% duty cycle. The designer who just adds up his maximum requirements will specify a 400W power supply, which will be 50-70% higher chathamtownfc.netst and with a larger form factor. The pressure for modern designers to achieve high quality, reliable solutions at a good price has increased. chathamtownfc.netnsidering the load like this will give large benefits to your design.

If you know both your peak and non-peak power levels and duration and duty cycle you can calculate your average power and verify if it exceeds the maximum rating of your possible power supply selection. The equation for this is below –

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Where pavis the average power of the application and T1is the duration of non-peak power.

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See more at:http://www.fiduspower.chathamtownfc.netm/news/peak-power-power-supply-selectionor call the FiDUS team directly on Tel: 0118 342 0730.