Power supply selection

boostbuck

Joined Oct 5, 2017
492
Your link points to a good description of these fans. It seems they require up to nearly 3A at 24V depending on the workload. So two 24V 3A(or greater) power supplies (or a single unit with twin output) would be sufficient.

Why do you think that SMPS supplies would be unsuitable?
 

Thread Starter

jnr

Joined Feb 12, 2018
3
Your link points to a good description of these fans. It seems they require up to nearly 3A at 24V depending on the workload. So two 24V 3A(or greater) power supplies (or a single unit with twin output) would be sufficient.

Why do you think that SMPS supplies would be unsuitable?
I have used a bench power supply at 2.5A set and fans run properly-with voltage drop at start.That possibly means there is a need for supply that can take the in-rush/spike current.
I have tried SMPS (Mean Well Switching Power Supply, LRS-200-24RS, 24V dc, 8.8A, 211W) but using a quick blow fuse 3.15A,I am expecting two anti surge fuses 3.15A to test again.
 

Jon Chandler

Joined Jun 12, 2008
986
The startup current may be 2× the run current or even greater. The Meanwell power supply should do the job for ONE fan, and maybe two but fuse it for 8.8 amps. Slow-blow is probably best for this application.

Why do you think that SMPS supplies would be unsuitable?
If the fan starts to spin up, then shuts down and tries again and again, start-up current is too great and it trips the SMPS protection circuits.
 

LowQCab

Joined Nov 6, 2012
3,937
It sounds like ???? that your only problem is with the Fuses.
The Meanwell SMPS will protect it's self and generally does not require Fuses on the Output.

It would be best to stagger the start-up of the Fans to avoid
nucense tripping of the built-in Protection-Circuit,
or You can use 2 identical SMPS's.

You could, alternatively, use a Series/Parallel Timed-Relay-Starter arrangement.
This would start the 2 Fans wired in series, then switch to parallel wiring after a few seconds.
This would also provide a 2-Speed operation option, manually-switched,
or automatically thermostat switched.
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Thread Starter

jnr

Joined Feb 12, 2018
3
i have tried slow blow fuses, fan starts on and off ,onand off...but doesn't run continuously.
therefore the switching power supply will not support it.Any suggestions?
Would a linear power supply be the solution?
 

LowQCab

Joined Nov 6, 2012
3,937
A bullet-proof, well filtered, 200-Watt, Linear-Power-Supply will cost over ~$200.oo to build.
A better plan would be to use 1-Fan on your existing Power-Supply,
and buy a second, identical, Power-Supply for the second Fan.

This assumes that You insist on starting both Fans at the same time,
which the current Power-Supply can not handle.

If You start 1-Fan, and let it get up to speed before starting the second Fan,
You may have no problems.

There is also the option to start the Fans while having them wired in series,
then changing over to parallel wiring when cooling demand increases.
This can be accomplished by using 3-Relays for 2-speed operation.
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MisterBill2

Joined Jan 23, 2018
17,814
Max is absolutely correct. But if you insist on using fuses too small for the load you will not ever succeed in continuous operation of the fans. The fuse is to protect the power source, not the load, so use a fuse at least 10% above the supply current rating.
 
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