Why is my power supply input only rated from 100-240VAC?

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Most power provides have a score label that appears one thing like this:

Nonetheless, an in depth take a look at the power supply’s datasheet will often present absolutely the AC input voltage vary, from minimal to most. This is often 90-264VAC, or often 85-264VAC if the power supply has been designed for Japanese use.

Japan makes use of the bottom AC mains voltage, which is 100VAC nominal; nonetheless, brief length AC line droops or brown-out circumstances usually mandate a score right down to 85VAC. The UK is among the many international locations that use the best AC mains, with a nominal score of 240VAC.

The protection certification our bodies (UL, CSA, TUV, and many others.) mandate score of 100-240VAC be listed on the power supply’s label. Nonetheless, they consider a +/-10% tolerance for the power technology and transmission utilities. -10% of 100VAC is 90VAC, and +10% of 240VAC is 264VAC. All security testing is carried out on the high and low limits as listed on the power supply’s datasheet.

So, if the power supply label states 100-240VAC, it may often function over a wider AC working input vary. Nonetheless, all the time examine with the producer’s datasheet to verify this. Steady operation of the power supply over the datasheet’s specified AC input vary is not going to usually trigger any issues. In some instances, nonetheless, the utmost output power (complete watts) of the power supply could must be derated if the supply is working off an input voltage that is on the low-end of the desired vary. All the time examine the power supply’s datasheet for the desired minimal AC input voltage with numerous output load ranges. Deratings might also apply relying upon the power supply’s working ambient temperatures.

Ought to a label state 100/240VAC (note the slash) it “could” point out that there is a voltage choose change or jumper that is required to be set for the right working input voltage vary. Newer merchandise are likely to not have an AC choose change or jumper.

Worldwide, the AC mains power has a nominal frequency of both 50 or 60 Hz (cycles per second). Nonetheless, these frequencies are topic to variations by the power turbines in several international locations (particularly third world) and so the everyday AC frequency vary for power provides is 47-63Hz.