Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter

meledeleon
meledeleon Registered Users Posts: 3
in Advanced Solar Electric Technical Forum #1
Hi, this is my first posting in the forum.
First, let me tell you that english is not my native language, so please forgive any mistakes in my writing.
Situation is this:
I´m running a new Samlex PSE 24275 inverter on an off grid solar panel array to power a rural home in Guatemala.
Installation has been made and, since this is a replacement inverter, we did not consider any modifications necesary. (Used to have a Xantrex 2424 120 60 which worked well, until we accidentally made a wrong connection and burned).
My problem is that even though my AC load is most of the time lower than 300 watts (which is the lowest reading in the inverter´s scale), the cooling fan has been working full time. It has only been seen to stop during very early in the morning (like from 3 a.m. to 6 a.m.) which is the most refreshing time of the day. Here, average environmental temperature is around 28-34 °Celcius during the day, dropping by morning to aprox. 16-18°C. I have not been confortable with this situation, so I place and aditional fan to provide some aditional cooling to the case of the inverter with no luck.

Wrote to the tech support representative from Samlex and mentioned high ambient temperature/poor ventilation could be the problem. However, acordingly to what I read from the owners manual, adecuate environmental temperature when operating the inverter ranges 0-40°C and I am sure, we have not reached such a high temperature, probably never will in this region. About ventilation, I think it´s more than enough, but even if it wasnt, I came out with something to force fresh air in through the windows of the room where the equipment is kept. Ventilation was greatly enhanced and temperature in the room droped significantly....nogthing happened. So, ambient condition, in my opinion, shoud not be a factor.

This is what the guy from Samlex said:

The fan in this unit is operated by a temperature sensor that senses temperature of a hot spot located on one of the internal power transformers and switches on the fan when the hot spot temperature reaches around 70 C. The temperature of this hot spot will tend to rise as the load increases. The temperature rise of the hot spot will also depend upon the amount of heat dissipation due to natural convection cooling (till the time the fan starts when the heat dissipation will take place due to forced air circulation and natural convection). Heat dissipation due to natural convection cooling depends upon the ambient temperature and natural air convection. If ambient temperature is higher, as in your case, heat dissipation is lesser and the temperature of the hot spot rises and triggers the fan at a lower power of the load. Your additional external fan that is blowing hot ambient air on the surface of the unit does not help in bringing down the temperature of the internal hot spot.

It is assumed that you have placed the inverter in a cool, open area with unrestricted air circulation. If the load increases, or ventilation is not adequate or environmental temperature is higher, the temperature of the hot spot may rise despite the fan running and once the hot spot reaches around 100 C , the unit will shut down due to over temperature protection.

Like I said before, the cooling fan does stop for a few hours a day, so, the automatic switch appears to be ok. I think this temperature sensor could be the problem.

The inverter works OK. My consern is to unecesarily operate the cooling fan, thus it will wear prematurelly.

Shoud I worry about it?
Can any body tell me how to locate this hot spot/heat sensor to try to reset-fix it?
Any alternatives?

Thank yor for taking the time to read this. Any help would be greatly appreciated.
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter

    Welcome to the forum.

    I'd certainly worry about it, as 300 Watts is nothing to an inverter supposedly rated for 2750.
    First thing to do is get a thermometer right near the inverter and see what the ambient temperature is around it when the fan is coming on.
    The second thing to do is check the wire size feeding the DC to the inverter to make sure it isn't having to draw too much current to provide the output Watts.
    That should cover the basics. In all likelihood the internal temperature is actually rising to where the cooling fan needs to turn on. With ambient temperatures approaching 34C that is not too difficult to imagine. The additional fan was a good move on your part. But you may have to do a little more rearranging to increase airflow over the unit.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter

    i have to correct you in your thinking as that 0-40 degrees c is not the environmental temp, but rather the operating temp of the inverter.

    http://www.samlexamerica.com/documents/product-specs/PSE-24275A_Samlex_Specifications.pdf

    when the ambient temps are to 34 degree c there is only a 6 degree margin left and the inverter does generate its own heat when operating so the fan most likely will not shut off even with the additional fan. do you have an infrared thermometer to easily measure the temps around the inverter as i would be cautious it could overheat and blow out?
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  • meledeleon
    meledeleon Registered Users Posts: 3
    #4
    Re: Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter

    Thanks for your replay Cariboocoot.
    All the DC connections were made with SAE 10 wire. Please tell me if the size is OK.
    I´m afraid I don´t have a thermometer at hand. However, I find hard to believe that under the same ambient conditions in which the Xantrex we used to have, a 3500w PowerBrite we borrowed for a few days and a small 300w Cobra, have worked as expected (cooling far operation), this unit has to be air cooled all the time. I very deeply respect your opinion, and I understand that you guys are the experienced ones, I´m just trying to explain my point why my primary suspect is that the inverter´s temp sensor could be damaged or not properly calibrated. Please let me know your thoughts.
    Thanks.
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  • meledeleon
    meledeleon Registered Users Posts: 3
    #5
    Re: Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter

    Hi Neil, thanks for your help. I actually had understand that the them of 40C was the top margin of ambient temperature for the inverter to operate properly. If as you said, it´s the operating temp of the device, then what does the 70C (the guy from Samlex mentioned) mean.
    Again, thanks for helping, and please let me know what you think.

    P.S. I have visited Pennsylvania several times and I liked it there very much.
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  • ywhic
    ywhic Solar Expert Posts: 621 ✭✭
    #6
    Re: Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter

    I would go with SAE Wire 8 or 6.. 10 SAE is rated for aprox 34 amps.. and the 8 is 45 amps.. 6 is 61 amps..
    (and yes I understand from reading that SAE is not as thick as out AWG size we use here in the US)..

    Maybe the slightly better wire will help drop resistance and let it run cooler as well.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Re: Cooling fan-Temperature sensor problem on Samlex PSE 24275 inverter
    meledeleon wrote: »
    Hi Neil, thanks for your help. I actually had understand that the them of 40C was the top margin of ambient temperature for the inverter to operate properly. If as you said, it´s the operating temp of the device, then what does the 70C (the guy from Samlex mentioned) mean.
    Again, thanks for helping, and please let me know what you think.

    P.S. I have visited Pennsylvania several times and I liked it there very much.


    that's a good question and one i can't answer. it may be they need to clarify what they are referring to with the temps, but to me listing an operating temp range is what the inverter's temperature is that it can safely operate at. you may need to confront them about it.

    what part of pa as there are big differences in various parts of pa?
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