Has anybody seen these yet?

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I want the one with the solar panel plug in and straight inverter. Probably want to run it with no grid power.

In it's day these were built right for the conditions. Ferro resonant were not that efficient and could produce heat, but with nasty power, sags, swells, spikes, ferro resonant are extremely reliable and long lived.

I just don't have any nasty power to feed it. Grid never goes down where I am. No big switching events near me either.

But who knows, nasty third world power could be coming back. Along with yurts and peddle bikes.

These things were rock solid. Good bet they still are. These took an expensive type of battery.

Best UPS.JPG
 
I think the ferroresonant UPSs were retired when electronics got better and online dual conversion UPS with pure sinewave output became the norm.
 
Todd0x1 said:
I think the ferroresonant UPSs were retired when electronics got better and online dual conversion UPS with pure sinewave output became the norm.
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Do you know of consumer grade double conversion units? I've looked for them to no avail.
 
zbang said:
California has agricultural checkpoints on the way in; mostly they're looking for large trucks and moving vans that might have ag. pests. I've never been stopped at one in my car.
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I did once a long time ago. Apparently that day 30 years ago they were mostly concerned with out of state oranges. That was all they asked about. I had no oranges in the car so it was a quick pass.
 
gadfly56 said:
Do you know of consumer grade double conversion units? I've looked for them to no avail.
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Yeah, I have a couple powerware 9125 -theyre pretty old now but still work good. There are tons of smaller plug in UPS that are double conversion.
 
Ferro resonant transformers are not that efficient, possibly under 90% and waste the rest out as heat. So in the larger sizes, larger loads running constantly, a double conversion unit running over 95% efficient would be indicated.

But it depends on what you want. If it's not critical uptime and you do not want the expense and hassle of batteries, the ferro resonant unit could be a much better choice for many applications.

In an industrial plant, the main computer you probably want to stay up when the plant goes down. So that's on a UPS (double conversion with batteries). But there are many other control power and instrument loads, sensors, scanners, that maybe you don't care if they go down with the plant, as long as they're protected from transients when the plant comes back up, they come up safely without going poof.

And it's not the whole plant load, just many remote located sensitive loads under 1 kW, the ferro resonant transformer is a great choice for those (no batteries but will otherwise take anything coming in from the line).

The more likely scenario is, they put sensitive non critical loads on small remote UPS's, then never change the batteries. The plant goes down, the sensitive load goes down, and stays down until the battery charges enough to satisfy the UPS controller, and someone comes along and pushes the reset button. Then the UPS gets replaced with another same unit because the batteries are toast after 5 years.

That's when you want a ferro resonant unit instead, indestructible, very long lived, no batteries. The efficiency does not matter much at the low load compared to the rest of the plant.

And back at the beginning, when they saw the cost of the double conversion unit for the large critical load, to save money they were sold line interactive units, which is just grid power with a spd filter network until it swaps to battery. Without the series inductance of internal line reactors, the spd's are kind of a gimmick on an industrial power system. You need them. But you have to be aware of their applications and limitations.
 
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