Compatibility issue between MS2000 inverter and Splendide 2100XC Washer/Dryer

In January we installed the new Magnum MS2000 inverter, replacing the failed ProSine 2000.   You can read more about all that here: http://mvvikingstar.blogspot.com/2013/01/a-peek-inside-magnum.html .  All had been well, until we did a test run  of the our Splendide Washer/Dryer running on the inverter - and it failed.  And if you want to get your propeller hat a spinning, read on.  If not, just know I have found some special case where there is a problem and still need to give the parties involved a chance to resolve it.  This post is just talking about what is failing...

OK, if you are reading on - here goes:  About 1/3 of the way into the wash cycle the Splendide starts moving the wash back and forth, mixing things up I guess.  And when on the Inverter it really goes nuts - lights flash, and the washer motion becomes jerky.  Clearly things are not happy.

Searching the internet found an obscure reference to a 'Known issue' between the Magnum inverter and Splendide washers.  An Email to the support department of both did get a quick response,  with each pointing the finger to the other :-)  (More on that to come I am hoping).

Always the inquisitive, I wanted to try to understand a bit better what was happening, so I broke out the Tek 222 O'Scope and started taking some 'pictures'   And here are some pictures of those pictures.  Sorry, I have not yet gotten the O'Scope connected to the Computer to directly download images, so we are doing it Old School - with a Camera.  (Ok, maybe not Old Old School - I am using a Digital Camera, not a Polaroid).

Here is the waveform of shore power, what a good True Sinewave inverter should emulate:

A 'Pure' Sinewave

Now TO BE FAIR - I have seen lots of waveforms from the Magnum that look what is above.  So lets not get the idea that this post is about an overall problem with the Magnum.   I am thinking it is really a case of when all the stars align that things go wrong.   And here is a picture of when things go wrong:

Failing Combination

Notice that kind of Hook circled in red?  What I believe I am seeing here is a problem with how the Magnum handles reactive loads, namely the inductive load of the washer / dryer drum motor.  That hook is when the machine fails.

Here is another picture, notice we still see the same flat-spot, but no hook?  Here the washer/dryer carries on:

This one seemed to work OK.

And here you can see the two images overlayed:

The Good and the Bad!

OK, so what is this all about?   Well, it appears to me there is a limitation in the Magnum inverter with inductive loads. Inductive loads are a special type of load known to cause Reactive Power to be drawn (as opposed to Real Power).  It is a major issue for shore-based power companies to deal with.  The problems, causes, and solutions are all well know.  But the application of this all is rather a dark art.  You can learn more here if you wish: http://en.wikipedia.org/wiki/AC_power#Real.2C_reactive.2C_and_apparent_powers

Back to Viking Star.  When looking at  how the Magnum handles other inductive loads (refrigerator, drill motor, drill press, vacuum)  the waveform shows a little distortion, but nothing dramatic -  and more important, no hooking.  So I am wondering what is special about the Splendide in the load it draws.  Maybe because the washer motor is on/off so much?   Maybe there is one too many corners cut in the Splendide power supply design? .  Another idea:  All the other inductive loads I tried were much larger overall then the Splendide - perhaps the problem is only when a rather light inductive load is placed on the Magnum.  Who knows, but all of this info I am sending to Magnum to see what insight / suggestions they have.

How to move forward, as we do need our washer/dryer working (and always using Shore Power is not an option!): 

• Overwhelm the Reactive Power with a much larger Real Power load.   Turning on a Space Heater to Low does this (tested and confirmed).  But it also uses a LOT of  power.  A 100 or 60w light bulb might do the same, need to experiment.
• Use a different inverter:  We know the Prosine works just fine - as long as it works at all.  It is reported that several 'cheap Chinese Sine-wave' inverters will also.  (This would be a sad situation where the Prosine and Chinese ones best the US Magnum...)
• Splendide to make their washer less susceptible to waveform distortions.
• Magnum to research this and improve their design (or perhaps I have a failed unit??)   Will see what happens next week.
• Add Capacitance to the load to counteract the washer's inductive load and reduce the waveform distortions.

A light bulb might work (can one still buy 40 or 60w bulbs these days??), but again it is wasteful of energy.  The last point holds the most promise.   I will try to secure a motor Run Capacitor - the key here is getting just the right value and that might need experimenting.   A more advanced version is using a 'synchronous condenser', in effect an inductor motor (no, really) driving no load.  This CAN be more energy efficient than just a light bulb or heater, and has the advantage of in effect looking like a self-adjusting run capacitor.  I tried experiments this morning using the unloaded motor on a drill press and a vacuum  - both worked great. (In fact, the 3rd photo above is the 'failing' waveform de-hooked by the unloaded drill-press motor.)   A try with a small box fan that I pulled the blades off of did not work - just too small to have any real impact.

There is a 'Treasure Shop' on the Island here, and will be picking up a car Monday.  I will go there and see if I can find a small motor and/or some run capacitors to try.  I think in the end this will be the real answer.

Will post the conclusion of this invention when get more info.  Till then:  Wow:  Boats and Systems.  SO much more than the house!

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