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What Can Happen When Input Voltage Exceed a Power Supply's Range?

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Author : Lee
Update time : 2021-06-29 11:38:12
From this article We will introduce new series articels titled "Some limitations of power supplies".Sometimes we can hear that "What can happen if I use my power supplies beyond their specified rated range?"To answer this question,we will review the specifications of power supplies and figure out some potential failures that could occur when operating power supplies beyond their specified rated range.
In Part 1 of this series, we will discuss the potential failures that may happen when the input voltage exceed power supplies' allowable range.


Part 2: What Can Happen When Output current Exceed a Power Supply's Range?
Part 3:What Can Happen When Working Temperature Exceed a Power Supply's Working Temperature Range?

Input Voltage Limits

From power supplies' nameplates we can see the input voltages are mainly 100-240Vac,100-130Vac,170-250Vac etc,an example from Top Power can show what it is as below in red circle,

 

There are some input ranges because in the world countries the mains voltages and their stability can be different greatly, and it is difficult to design a power supply that meets the input range for all applications. Assuming a power supply's input specification is "close enough" to an application's desired operating voltage can lead to failures if the power supply is operated beyond its limits actually.These failures can be considered as either components failures, system failures, or others, and each failure will affect power supply and system performance differently.
We focus on the components failures discussion.

 

Component Failures

>>>>Input voltage Exceeds rated one

Component failures happen when a component is damaged and no longer works as expected.Exceeding components' maximum operating voltage's input voltage can damage any component easily.Components which are put across in the AC input end such as X-capacitors,inductors,MOV, and bridge rectifiers are easily under stress and fail.If the input AC voltage exceeds their MAX. operating voltage,the results which are lead by the components failures are quite different.For example,bridge rectifiers are designed to convert and lower AC,will likely explode if falied and also make the fuse open,then the power supplies cann't work any more. However, inductors which are designed to stablize AC and reduce interference,will likely also explode if fail and make the primary circuit components damaged.
 

Other components are also easily damaged under high input AC voltage,so before using power supplies we should consider the input voltage.

>>>>Input voltage lower than rated one

Under voltage input may also cause component failures.When operating a power supply below the min. working voltage, the current in many components will increase accordingly. The fuse, rectifier,inductors and other components that deliver this increased current will all consume more power, resluting in an increased temperature and chance of failure. Magnetic components, such as a power factor correction (PFC) choke, will also deliver more current and as a result see their inductance drop or saturate entirely. 
From above we can see lower input voltage also cause higher temparature of power supplies and increase failure chance of power supplies.

If you are not sure input voltage issue when buying power supplies,please contact Top Power Sales Team for more details.

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