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FET cemetery
Regular Member

Joined: 17/04/2024
Location: Australia
Posts: 77

Posted: 10:17am 25 Oct 2026

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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.
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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

No stone unturned, no FET unburned.

FET cemetery
Regular Member

Joined: 17/04/2024
Location: Australia
Posts: 77

Posted: 10:36am 25 Oct 2026

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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.

No stone unturned, no FET unburned.

analog8484
Senior Member

Joined: 11/11/2021
Location: United States
Posts: 245

Posted: 05:56pm 25 Oct 2026

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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

Godoh
Guru

Joined: 26/09/2020
Location: Australia
Posts: 715

Posted: 08:39pm 25 Oct 2026

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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

davros
Newbie

Joined: 24/02/2025
Location: Canada
Posts: 31

Posted: 10:20pm 29 Oct 2026

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Now THAT is a toroid!! swoon....

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