Failsafe for Fan Cooling

HydroDC · Jun 10, 2015

I use CPU coolers for my DIY light. To protect the COBs in the event of a failure of the 12V DC power supply for the fans, I'd like to add a relay switch so that if the PSU fails, the COBs won't get power. I know little about these relays. Would something like that shown below be a good choice or is there something else I should consider?

salmonetin · Jun 10, 2015

...pardon HydroC... any electric scheme for do that with an Solid State Rele?

...i saw some info on ssr maybe help you a bit...

http://www.omron.com/ecb/products/pdf/precautions_ssr.pdf

http://www.digikey.com/Web Export/Supplier Content/Crydom_172/PDF/crydom-techtip-why-use-ssr.pdf?redirected=1

http://www.ssousa.com/application-notes/AppNote040_Solid-State-Relays-vs-Electromechanical-Relays.pdf

...i saw other info about ssr and arduinos... but this time let atduino way out....

...but its only my inexpert opinion...

saludos

rufus01 · Jun 10, 2015

Actually he should work.
Or you can use a thermal switch connected to the heatsik so if the temperature rise over the rated value he will break your driver power line.

salmonetin · Jun 10, 2015

...a thermal switch can activate an SSR?... if yes... how to?...

...rufus... some example on thermal switch... ?... i cant remember but i saw a guod answer with something similar... or maybe a thermal switch... but i cant remember the thread or post... im too bad searching things on riu... sorry..

saludos

Atomizer · Jun 10, 2015

Be aware that solid state relays tend to fail "closed", mechanical relays tend to fail "open".

rufus01 · Jun 10, 2015

Atomizer said:
Be aware that solid state relays tend to fail "closed", mechanical relays tend to fail "open".

So in this case a SSR is even better, worst case scenario the plants don't get light for few hours to a day.

rufus01 · Jun 10, 2015

salmonetin said:
...a thermal switch can activate an SSR?... if yes... how to?...

...rufus... some example on thermal switch... ?... i cant remember but i saw a guod answer with something similar... or maybe a thermal switch... but i cant remember the thread or post... im too bad searching things on riu... sorry..

saludos

No, a thermal switch is a switch like the one used for turning on/off any house light, he just operate when a rated temperature is reached.
A relay is an electro magnetic switch that can be activated by the presence of a lover volage, like the fans power supply in this case.
If the power supply fail the switch will open turning off the driver.

Atomizer · Jun 10, 2015

If the SSR fails the power will stay on. With an electro-mechanical relay, it wont

A disc thermostat might do the job, but it`ll reconnect the power once it cools down, a thermal fuse is another option.

rufus01 · Jun 10, 2015

Yes, disc thermostat, sorry my mistake :mrgreen:

salmonetin · Jun 10, 2015

please atomizer can you share more info about disc thermostat and thermal fuse used with reles?

thanks in advance

...i saw your pic... brand?... model?...

...semi-autoanswer... the disc thermostat on pic its a Selco

3/4” Disc Thermostat - Manual Reset - model: SES-L200M

...Wilson... recuerdame mirar cosas del fusible termico... la peña no esta por la labor... asi que Wilson te invito a infusion y petardo en la cueva....

saludos

rufus01 · Jun 10, 2015

available with manual reset, so the light will not keep going ON/OFF as the heatsink temperature drop.

rufus01 · Jun 10, 2015

salmonetin said:
please atomizer can you share more info about disc thermostat and thermal fuse used with reles?

thanks in advance

saludos

Or you use the relay or the disk thermostat or the thermal fuse.
Only one of these solutions.

salmonetin · Jun 10, 2015

...i think i can use all... at the same time.... ...seems to me its a similar way to industrial contactors way... .. but now im only learning your hows to about these hardware pieces...

...thanks a lot Rufus01... but please following sharing more info... electrical squemes ... pros and contras..

...i like a lot learn on all protections way... ...sometimes i need refresh the info with others opinions ... other hardwares pieces... other how too...

...thanks to all for sharing...

saludos

HydroDC · Jun 10, 2015

Atomizer said:
If the SSR fails the power will stay on. With an electro-mechanical relay, it wont
A disc thermostat might do the job, but it`ll reconnect the power once it cools down, a thermal fuse is another option.

Thanks for all the feedback. I read the articles you posted, Salmonetin. And Atomizer, fail-unsafe doesn't sound as good as failsafe, does it?

rufus01 · Jun 10, 2015

salmonetin said:
...disk thermostat or thermal fuse or thermal switch... for my pov....actuators on the control side of reles o contactors way... but repeat... its only my personal opinion...

You do not need any actuator for the relay, he will be powered directly by the 12v power supply wired in parallel with the fans.
When powered the contact is close and the Led Driver is powered.
When/if the 12v power supply fail, the relay will be released and the contact open so the Led Driver is turned OFF.
So you need a realy "normally open" that when receive some VDC change the state to "close".
Is really very simple but if you feel the need i can open MSPaint ad draw something :bigjoint:

dandyrandy · Jun 10, 2015

I used a 145deg thermal on each arctic 11. Normally closed.It's's in the relay coil circuit. 12v supply drives fans and picks up relay. Ac to led supplies is applied through relay contacts. Also have a sail switch on the blower output. No air, no lights. In process of changing design so air circ fan runs only when lights off. I get enough from the arctic 11's (9) when the lights are on. Also need to reduce air flow through carbon filter when lights are off. Need to modify a controller so the speed pots are switched using different pots with relays. I only need a gentle (maybe 40 cfm) with lights out. I think I need to look into a pic controller and write some code.

rufus01 · Jun 10, 2015

The disk thermostat is even simpler, you just connect it somwere in your LED driver main fase input.
Probably it's a good option for people that put the drivers nearby the lamp/dissipator.
If you are running all the powers supply/drivers outside the grow room is easier to stick with the relay option.

P.S. with the disk thermostat, having the main AC connected near to the heatsink require a very good cable/connector managment and possibly a good grounding.

rufus01 · Jun 10, 2015

Well, actually Dandy, having the disk thermostat wired on the 12v line with the relay is safer and smarter :mrgreen:

Now i understand what Salmonetin was asking

Randomblame · Jun 10, 2015

I'm usig this one
ebay part number:

400926743510

rufus01 · Jun 10, 2015

Dandyrandy I think this is more ore less your fail safe setup.
behold the masterpiece :mrgreen:

Failsafe for Fan Cooling

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