Microwave blew capacitor inside inverter

[The_Nerdy_Traveler]

I'm out in the field, I hook everything up - battery to MPPT, PV to MPPT, power up via circuit breakers, connect 2000W inverter(most likely modified), Sola Constant Voltage Transformer, then the microwave (700W 1100W/120VAC).

First time using the microwave and CVT.

Microwave powers on, but will not power up to heat up food. I take out the CVT, and it the microwave heats up, albeit louder noise. This really should have been my first clue, but I thought that I had a defective CVT since it is vintage.

Tried to make some microwaved popcorn, nope. Booooom! Out comes the smoke from the back of the inverter. Power is still on, just no more heating up. Immediately turn off inverter. Open it up and the middle capacitor has blown, and it looks the one next it was going that way as well.

Inverter is still producing AC, so I will replace all 3 capacitors.

Any ideas here as to what why the capacitor blew?

From what I read on-line and here: 2000w inverter should have handled the power ( 700*2=1400). Use a long extension cord next time to keep surge down. Inverter probably cant handle the microwave to begin with - too cheap.

 

[chrisski]

Inverter probably cant handle the microwave to begin with - too cheap.

I think this is the answer.

I have an 1100 watt microawave that pulls 1800 watts from the inverter, which with DC to AC losses comes to 2050+ watts from the battery. This was a quality Samlex 2000 watt 12 volt inverter.

There's some good videos cheap, smaller than they should be inverters going up in smoke on YouTube.

 

[tigerwillow1]

A bunch of years ago I looked at the output of a Sola CVT on a scope. I don't remember any details other that the output was a butt-ugly mangled waveform. This was with a sine wave input.

I've done a bunch of testing microwaves with MSW power. In general, conventional microwave ovens run at about half power and may buzz some. Their power draw and cooking power is directly proportional to the MSW voltage peak, so the higher the inverter's DC input voltage, the more power the microwave runs at. MSW peaks are never as high as sine wave peaks for the same RMS voltage. The "inverter" microwaves I tried would not work at all on MSW power.

I realize none of this answers why the caps blew. Just passing info along. Maybe the CVT does a number on the inverter.

 

[Solar Guppy]

The microwave (700W 1100W/120VAC).

Those power levels are the amount of microwave energy which is available to heat and cook food, not the power the appliance draws from the mains. All microwave ovens are listed by their output power.

 

[73powerstroke]

Why the transformer? Maybe that was the real killer. Inverter is probably way too small also. Definitely repair it if you can.

 

[Bud Martin]

Can we see the pictures of the damaged inverter?

 

[wholybee]

Why the transformer? It will add considerably (up to 50%) to the load, and will have significant draw itself even when the load isn't powered. Both bad for battery run time. And an inverter running off a battery should have a rock solid voltage, no need for an additional regulator.

You probably overloaded the inverter, not accounting for the efficiency loss in the microwave and losses in the transformer. But that wouldn't damage the capacitors. Was this an old, used inverter? The capacitors might have just been end of life, and powering it on killed them.