I think the hassles Silver is having is not peculiar to the Axpert but most inverters and UPSs cannot accept the current from these portable generators. They tend not to produce a pure sine wave. Your generator is a fixed installation with a proper alternator. My Axpert runs fine on my gennie again a proper alternator.

 

 

I think owning an Axpert is like being the parent of a teenager. The thing works but does stupid things and frustrates you.  I find the Axpert together with a Victron battery monitor a good bit of kit. I looked at several options but the Axpert's price won me over. At a 1/3 of the price of its competitors I am prepared to put up with/work around its idiosyncrasies. 

I think the hassles Silver is having is not peculiar to the Axpert but most inverters and UPSs cannot accept the current from these portable generators. They tend not to produce a pure sine wave. Your generator is a fixed installation with a proper alternator. My Axpert runs fine on my gennie again a proper alternator.

 

 

I think owning an Axpert is like being the parent of a teenager. The thing works but does stupid things and frustrates you.  I find the Axpert together with a Victron battery monitor a good bit of kit. I looked at several options but the Axpert's price won me over. At a 1/3 of the price of its competitors I am prepared to put up with/work around its idiosyncrasies. 

I have a couple of sub-R1000 1000VA up's for PC's, one of which is a Powercom and they don't have any issues being powered from the same genset. But, they're too small to power the axpert in return. 

The 3000rpm gensets doesn't generate a pure enough sine wave for UPS/ inverter use. It is fine for most of the other appliances. I have also found that my friges and freezers doesn't like that power too much. If I run on the genset for too long, it doesn't cool as it is supposed to. I suspect it has to do with the sinewave and the compressor. My 35kva 3 phase 1500rpm genset has no such problems. At one stage I had problems with the rpm / load controller on the genset and the UPS's immediately started complaining once the frequency changed. 

 

I suspect that if you want to run an inverter from a genset, you will need a 1500rpm diesel and they are quite pricey. Haven't seen many below 20kva.

McWidowmaker you beat me to it. The diesel generators have a large flywheel and run slower. The variation when the unit comes under load is less. The little bit of reading I did last night mentions that these portable gennies can produce a sine wave since their basic construction is the same but that the wave is not pure enough (somewhere someone mentioned a tolerance of 3%). I think Yanmar produce a 2kw portable diesel generator but cost something like R18k.

 

Silver your first step would to be to clean and service the gennie (esp the air cleaner) attach an Efergy  monitor and adjust the speed of the gennie until you have 50Hz and see whether it can maintain 50Hz under load. You may still get it to work. The speed of the gennie affects both frequency and voltage. Some fish-tank enthusiasts whose site I had a look at were of the opinion that frequency was more important than voltage as long as the voltage was not too low.

One can also check the wave with an oscilloscope, but it will just confirm what we suspect, not really give a solution to the problem. 

I'm only speculating, but I think the problem is more about the frequency, 1) not being in the range expected by the inverter and 2) changing rapidly under varying loads. I do not think the inverter would be that sensitive to the AC waveform and if it is a little distorted - you should see what the ESKOM waveform sometimes looks like. The gennies with the bigger flywheels probably work better with these inverters because the frequency does not change suddenly with varying loads.

Thanx for the info guys. I'll play around with it over the weekend, perhaps. I have an energy and will see what it produces. 

Silver - how did it go? A friend wants to swap my 10kVA 3 phase generator for a new 7.5 kVA Briggs and Stratton. I am tempted but.... need to know whether small petrol generator cut the mustard.

Silver - how did it go? A friend wants to swap my 10kVA 3 phase generator for a new 7.5 kVA Briggs and Stratton. I am tempted but.... need to know whether small petrol generator cut the mustard.

Hi, 

 

Sorry, I haven't had time to start the genie up yet. Will see if I can tomorrow. 

I know the Victron inverters have a setting that allows it to work with dirty genset power. By default it's also a little particular about what you feed it.

 

Small note on suggestions of testing with an oscilloscope: Be careful not to blow it up when using it directly on mains. The scope ground is often grounded to the mains ground. In that case, you can simply leave the ground clamp on the probe disconnected (as neutral will be bonded to mains earth already). If unsure, there are two ways I know of: 1) use a mains isolation transformer to isolate the scope or 2) if you have a dual channel scope, put live on the one channel, neutral on the other, then tell the scope to "add" the two channels, and invert channel 2 so it subtracts them instead.

 

Also, my scope is limited to 250V. I would probably feel safer using a 10x probe if I wanted to do this.

I don't have a scope ;(

Keep an eye on gumtree. Old analogue scopes sometimes go for as little as R500. Good analogue scopes can be had for as little as 1.5k. A low-end new scope usually starts around 3.5k, and for digital it's quite a bit more. The USB-scopes aren't necessarily much cheaper and often have way less bandwidth (though that won't matter at all in this application).

 

If you buy a secondhand scope, be sure you know how to work one so you can test it before buying it. By that I mean... just google a bit and read some howtos. Every scope has a test point, so all you do is hook the probe up to the test point and toggle the level/timebase buttons until you see the 1khz square wave.

 

I bought this scope for 1k a few months ago:

 

Silver - how did it go? A friend wants to swap my 10kVA 3 phase generator for a new 7.5 kVA Briggs and Stratton. I am tempted but.... need to know whether small petrol generator cut the mustard.

Hi Chris, 

 

What make and model generator do you have?

It is a 3 cylinder ST Lister driving a 10kVA Compton Greaves 3P generator.

Old post, but for the record I wanted to share that I use one of those briefcase type generators which produce a pure sinewave output. I think the brand is called Generac. It has a subaru engine, 2500w pure sine wave output as well as dc output for charging 12v batteries. This works perfectly on my axpert mk2 (2500w) hybrid.

If I remember correctly, I paid R9500 for it about a year ago and it was much cheaper than the honda 2000 or just about anything else around that produced a pure sine wave output.

Welcome wunluv ... thank you for this heads up!