Every couple of years I clean out the mesh behind the fan in my SEA inverter




It's a 48V 3.8kW (off grid) unit, very conservatively rated. Was advertised as having a mean time to failure of 20 years, it's 23 years old now and still going strong (it's nice having a working WG inverter with spares a a backup). Took some pics of its innards if anyone's interested.
[


I think SEA went out of business a few years ago. Product too good I guess...
The toroid is big, 240mm diam with windings and about 90mm thick. Primary and choke look to be wound with 16mm cable. I like the way they've mounted the choke on the front of the transformer.



Close up of the power board


And the dirty fan filter

It's a full sinewave inverter, I think they threw in some extras:


From memory that's loaded at about 3kw, maybe a bit more. The distortion is audible sometimes, if you turn on the 1.8kW coffee machine while the induction hotplate is going the hotplate makes quite a buzzing sound.
Never had any electronics fail or complain, can't hear anything untoward through the hifi or tv.
Unloaded the waveform is a bit weird, kind of looks like each half cycle is made up of 6 or 7 straight lines. Again, everything runs no problems.

Loaded up in summer it runs hot, I've measured the toroid at 105C. Keeping the fan clean is a necessity.

Thanks for sharing.  I find it interesting that a 20+ year old inverter apparently has a quite large (toroidal Sendust core?) inductor choke on the transformer primary.  If my understanding is correct, it certainly predates similar designs in the DIY inverters on this forum.
Edited 2026-10-26 03:57 by analog8484

Nice one, they had a name as good inverters back in the day.
They had a factory at Moruya in Southern NSW  a long time back.
There were other inverters made with torroids back in the 1980s, Rainbow Power in Nimbin made some, i had a 600 Watt one of theirs back then. That was in the days when a 600 watt inverter was considered big.
First inverter I ever saw was a Honeywell inverter, which was a 12 volt motor driving a small generator.
pete