Author Topic: Mod inverter question  (Read 3061 times)

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greenkarson

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Mod inverter question
« on: December 14, 2014, 09:43:34 AM »
Not sure where to post inverter question so feel free to move this wherever it belongs.

Let me start by giving too much information for a simple question. Ha

I have a remote cabin. no hydro or cell signal within many kilometers. So I have a 100w turbine in a creek and 200watts of solar a couple of huge agm batteries and a cheapish 1000w mod sine wave inverter. I use a honda eu2000 inverter generator when not on battery power. A couple of months ago I installed satellite internet there (xplornet but the modem says hughs) I've been nervous running the modem off the mod inverter so I've been using only the honda generator. I'm only there on weekends. But Santa is bringing me one of those internet cameras that you can check with a app on your smart phone. So I'm wanting to leave my inverter on when I'm not there to power the internet. But will the mod sine wave inverter kill the modem?  Any input would be appreciated
Thanks

Flux

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Re: Mod inverter question
« Reply #1 on: December 14, 2014, 10:29:07 AM »
Those that have most luck with modified sine inverters are those who don't know about the limitations. If you have faith most things work  ( at least up to a point).

I don't have the courage to try anything I suspect may be a problem so I can only comment on what I see others get away with. TV and radio almost always work. Laptop and drill chargers are a gamble, the simplest chargers work, the complex ones often don't, they die or shut the inverter down. Probably the same with a modem, most will be ok, the odd one may not.

Power tools all work except those with variable speed, the thyristor controllers just can't handle it.

Fortunately most things are now cheap enough to take a risk, quite often even things that don't work survive but that is not always the case.

Wait to get other peoples opinion but I suspect a modem will be ok

Flux

mab

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Re: Mod inverter question
« Reply #2 on: December 14, 2014, 11:48:48 AM »
most modern 'electronic' power supplied don't care if it's MSW, pure sine or d.c. so I would expect your (presumably modern) modem to be fine. most of the smaller UPS's (uninterruptible power supplies) are MSW - I think - and these are designed to keep computers and the like running.

I find that most things will work on MSW but there are odd exceptions:- my battery drill charger doesn't like it - when I heard it making a strange noise I unplugged it and it didn't take any harm. Curiously I didn't have much trouble running a variable speed drill on my MSW, but I suspect that may be because I was running a freezer at the same time, and the induction motor of the freezer may have been making the waveform more sinusoidal (just a guess).

dnix71

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Re: Mod inverter question
« Reply #3 on: December 14, 2014, 12:28:02 PM »
What is the idle draw? A 1000 watt inverter is quite a bit larger than you probably need. I ran a Westell off 12vdc directly. It wasn't what the wall wart put out, but the modem had a full wave bridge inside and didn't care.
The larger problem with MSW inverters is the peak voltage. Many run 145v with a flat top. Real sine is 171v at the peak.

OperaHouse

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Re: Mod inverter question
« Reply #4 on: December 14, 2014, 01:08:19 PM »
As said before, most wall wart converters just convert the power into DC before the switcher turns it into the lower operating voltage.  With an ohm meter toy can check for resistance of the AC pins, under 2000 ohms.  I run all my electronics on DC partially because it is more efficient and because I buy destroyed inverters.  Each fan draws about 120ma so I remove all of them and go for natural ventilation to conserve current.  Get a small inverter and dedicate that to your electronics.   I happen to use a RC filter for extra protection because my chargers are on the AC line to the fridge.  That absorbs any motor spikes.   All my inverters are MSW.  I have a Prosine 2.5 but have never connected it up.

greenkarson

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Re: Mod inverter question
« Reply #5 on: December 14, 2014, 05:00:27 PM »
My batteries and inverter are in a shed about a 100' from the cabin with just a ac line running to the cabin. So I'm limited to one inverter for now.  I'm not to conserned about the idle draw. With the turbine and the solar. I've had good luck so far with the tv no issues. I think I will give it a try.   

That leads to another unrelated question. Does anyone know if these security cameras are constantly uploading or just when they are accessed? Being on satellite Internet I need to keep my bandwith fairly low

dnix71

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Re: Mod inverter question
« Reply #6 on: December 14, 2014, 11:36:40 PM »
Depends on the security camera. The point of uploading is it prevents an intruder from destroying the recording. You should be able to program it to take a still every 4 seconds and that would suffice.

Xan

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Re: Mod inverter question
« Reply #7 on: January 23, 2015, 05:20:01 PM »
I have several circuits powered by MS inverters and although you can get away with much there are a couple of problems I wish to share.

a) I have found it very bad to attempt to run anything with a capacitive fed supply in it. Due to the high harmonic content of the waveform excess current flows in that capacitor. One device I had, the component actually cooked up. In another situation just a couple of weeks ago I was trying a master/slave switch and that fried first time I used it on the circuit. This time it wasn't the capacitor but excess current went through a fusable resistor. Not enough to actually fuse the resistor (it went black though) but the heat cooked the zenner diode next to it. I say NEVER run devices with capacitive fed supplies from a MS inverter.

b) Some MS inverters do not like to feed loads that are on the end of long cable runs. I am picking this is due to the small capacitance inherent in cable runs making the inverter go unstable. Again, this would be due to the high harmonic content.