Hi ,
Just some suggestions :
I´ve found this thermal fuses on voelkner , just if you want to be really sure and don´t have this on/off effect , they can handle 10 A and react at 93 C° so for one PCB it´s enough , but in worst case they must be replaced. The advantage is , that they cut the complete power off and it remains off. So you can use them direct to power.
----> http://www.voelkner.de/products/3382/Temperatursicherung-93-C.html
I don´t found something similar on mouser , maybe someone else?
Other Idea that i have was to use a circuit breaker like this ----> http://de.mouser.com/ProductDetail/TE-Connectivity-PB/W28-XT1A-7/?qs=sGAEpiMZZMvNllHT6Fj2fjyJLrUxEIJB5lXHI1hSl5Q%3d (There are no pics , but look into datasheet and you know how they look.)
They offer a overload protection of 7A , this is just right for one PCB , and they are very sensitive to ambient temperature , so if the airfow form fan works, they opperate normaly , but when the fan stops they overheat and break the circuit permanently , even there is no overload related to the current. The big advantage is that they are resetable , so they remain off even you push the button
But this might take some time to find the real life conditions and for testing to find the right one. But if it works , it´s sureley a real secure and comfortable sollution , whitout replace any parts or have this switch between on /off. There are also higher ones , with 15 A so its posible to realize one sollution for both PCB. I think this can work , but it´s hard to find the sweet point , so that they dont react under normal condition but quickly react under overtemp.
If you find the right one , its possible to drill a hole in the original cooler and bring them inside like a temp sensor.
This is what i mean : (ok nearly like this
)
http://i59.tinypic.com/hs759c.jpg
Maybe some suggestions from the experts here?
I don´t try with those circuit breakers so far, but i have a bimetal switch at home and at the right place it´s possible to bring them to react only if the fan is off. For those circuit breaker i think you have to operate them to the limits , maybe something near to overload point, so that they remain on if they are cooled from the fan, but without cooling and with the additional heat from the chips , they can switch off quickly.
If someone want to try this, the best thing is to choose one sensor for both PCB , so if there is an overheat both PCB´s goes offline, and to find the sweet point, choose a summer day with high temps, so that you can be sure that it´s not react under "normal" conditions, but also check under lower outside tems if it works properly, then get the fans off and check if they break the circuit. In the datasheet are the reaction times for different situation of overload, so you have to add the ambient temperature correction factor , to calculate wich one to choose.And you want to do real perfect , you can use a 3 Pin Screw terminal for soldering on PCB , one pin without connection to PCB just directly to the circuit breaker , and the original + pin is conected to PCB and you wire this directly form Sensor.
This is the affect of the ambient temp to the reaction:
http://i57.tinypic.com/vn164l.jpg
What do you guys think?
Just some suggestions :
I´ve found this thermal fuses on voelkner , just if you want to be really sure and don´t have this on/off effect , they can handle 10 A and react at 93 C° so for one PCB it´s enough , but in worst case they must be replaced. The advantage is , that they cut the complete power off and it remains off. So you can use them direct to power.
----> http://www.voelkner.de/products/3382/Temperatursicherung-93-C.html
I don´t found something similar on mouser , maybe someone else?
Other Idea that i have was to use a circuit breaker like this ----> http://de.mouser.com/ProductDetail/TE-Connectivity-PB/W28-XT1A-7/?qs=sGAEpiMZZMvNllHT6Fj2fjyJLrUxEIJB5lXHI1hSl5Q%3d (There are no pics , but look into datasheet and you know how they look.)
They offer a overload protection of 7A , this is just right for one PCB , and they are very sensitive to ambient temperature , so if the airfow form fan works, they opperate normaly , but when the fan stops they overheat and break the circuit permanently , even there is no overload related to the current. The big advantage is that they are resetable , so they remain off even you push the button
But this might take some time to find the real life conditions and for testing to find the right one. But if it works , it´s sureley a real secure and comfortable sollution , whitout replace any parts or have this switch between on /off. There are also higher ones , with 15 A so its posible to realize one sollution for both PCB. I think this can work , but it´s hard to find the sweet point , so that they dont react under normal condition but quickly react under overtemp.
If you find the right one , its possible to drill a hole in the original cooler and bring them inside like a temp sensor.
This is what i mean : (ok nearly like this
)http://i59.tinypic.com/hs759c.jpg
Maybe some suggestions from the experts here?
I don´t try with those circuit breakers so far, but i have a bimetal switch at home and at the right place it´s possible to bring them to react only if the fan is off. For those circuit breaker i think you have to operate them to the limits , maybe something near to overload point, so that they remain on if they are cooled from the fan, but without cooling and with the additional heat from the chips , they can switch off quickly.
If someone want to try this, the best thing is to choose one sensor for both PCB , so if there is an overheat both PCB´s goes offline, and to find the sweet point, choose a summer day with high temps, so that you can be sure that it´s not react under "normal" conditions, but also check under lower outside tems if it works properly, then get the fans off and check if they break the circuit. In the datasheet are the reaction times for different situation of overload, so you have to add the ambient temperature correction factor , to calculate wich one to choose.And you want to do real perfect , you can use a 3 Pin Screw terminal for soldering on PCB , one pin without connection to PCB just directly to the circuit breaker , and the original + pin is conected to PCB and you wire this directly form Sensor.
This is the affect of the ambient temp to the reaction:
http://i57.tinypic.com/vn164l.jpg
What do you guys think?