Fuse for LED strip controller

Tomas25's picture

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Joined: Nov 08, 2020

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Fuse for LED strip controller
November 9, 2020 - 12:17am

Hello,

I am building LED strip controller with esp32 and 5V-5A power suplly. During prototyping I somehow touched output (5V) wires from power supply, made short circuit and they started to melt down. Power supply shoud have short circuit protection and I think, this was due to thinness of jumper wires I used during protoryping. 

However, I would like to add fuse to avoid fire things up in some improbable similar situation. I am thinking about adding fuse on input or output of power supply. I measured power supply input current with fully bright strip (~130mA). What do you think is the best solution - add 5A car-like fuse on output or 160mA 250V fuse on input of power supply?

Thanks!

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Michal Podmanický's picture

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Joined: Nov 06, 2020

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I dont think you need to fuse the output of PSU, if there is a short protection build in. 

Probably, the only case u need it there is in poor designed PSUs, when the short protection ativated (long term) couses too much heat disipation to burn it down, so it is better to break the whole output.

 

On the mains side (230v) the fuse is the must.

Michal Podmanický's picture

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Another thing, its a good idea to find, how your PSU behave after output overload and short: 

-One case is the PSU decrease output voltage to maintain 5A.

-Another case is the PSU disconnect the output completelly.

-There can be thermal protection built in.

 

You have to count with fact, the 5A is enough to burn the wood where your Led strip is mounted, in case of Led damage resulting to some ohmic resistivity, or how you mention in case of thin wires.

Michal Podmanický's picture

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However, if you deside to check how the output protection works, start with light overloading (not shorting) like car bulbs or resistive wire and check the heat dissipation of PSU. The hard shorting the cheap China PSU can or cannot handle.

Sourav Gupta's picture

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You are using a meanwell PSU which has a proper input protection using slow blow fuse. It also has a output shortcircuit protection as a hickup mode. The problem lies in the wiring. The wires are too thin and when the shortcircuit happens the current flow never cross the 5A mark where the SMPS detect it as a shortcircuit. This same thing will happen even if you add up a separate fuse. Because, when the rapid current flow in the sortcircuit reach, lets say 3A, the wires end up burning it self due to the in appropriate current draw properties of the wires that is required for this application.

Use at least 1mm electrical wires that is used in electrical wirings. Best is to go for 1.5mm wire.