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 Post subject: Sola ferroresonant power conditioners
PostPosted: Nov Wed 24, 2021 6:52 pm 
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Location: Portland Oregon
What are peoples thoughts on the Sola power conditioners? I’m thinking that they may be a useful item under the bench to run voltage sensitive devices like tube testers, etc. They also serve as a power conditioner, a surge protector and it looks like it will work as an isolation transformer as well.

I heard that these are auditory noisy devices though.

Does anyone use these and what do they think about them?


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Wed 24, 2021 7:50 pm 
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I have used them to run a sensitive IR detectors that were prone to false triggering from electrical noise.

An older (used) unit may hum, or not, if it is running rather warm then the precision cap may be leaking or had a change in value.

Be aware not to oversize it for the average load or it won't be sensitive to line fluctuations.

GL

Chas

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Wed 24, 2021 8:55 pm 
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Joined: Mar Thu 29, 2018 3:41 am
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Location: Portland Oregon
Hi Caz,

There is a 2KVA unit for sale locally so I am not going to be buying a new unit.

I was thinking of plugging in all of my vacuum tube test instruments into the Sola. I’m thinking that the Hickok Tube tester with the pulsating DC is especially sensitive to line noise and voltage fluctuation. This could also be true of other instruments and potential radios as well. I have a fair amount of line noise in my home and also see the voltage vary probably +/-3 V. I can’t see myself ever loading the unit over 500W and it will be usually being run at less than 100W.

Do you think that this unit is oversized? I am correct in that this is also an isolation transformer, right? According to the schematics, it looks like it is.

I just called Sola and they told me that, ideally, I should load the power conditioner to 40% load. If I don’t, it will run warm, shortening the life of the capacitors. Do you have any experience with running these units lower than 40% power. I’ve read that they will use 25%power running with no load.

Dave


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Wed 24, 2021 9:59 pm 
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Location: Long Island NY
You have to be careful with these as there are many variations. Some have isolated secondaries but others do not. Also, some have radical output waveforms that are full of harmonics. Many radios will exhibit more noise and "buzz" on them. Sola did make versions that were filtered to clean up the harmonics.

Whether it is worth it or not depends on the equipment you intend to plug in. If the equipment has an internal regulated power supply then you probably don't need an outboard regulating transformer. Most tube testers require you to set the line voltage to a mark on the meter scale after you put the tube being tested in the socket. That compensates for loading of the tester's transformer as well as the line voltage, so you still have to do it whether you use a regulating transformer or not.

Where regulating transformers do best is in situations where the equipment is going to be on 24/7 and the area gets a lot of line voltage fluctuations. If the equipment is only going to be on for a few hours at a time and the line voltage is reasonable with no big fluctuations, a regulating transformer is overkill. My opinion FWIW.

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 12:04 am 
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Location: Portland Oregon
Thanks for the reply Chris,

The thing that really attracted me to this unit is that it is a noise filter, voltage stabilizer, and isolation transformer all in one. I’ll take my DVM when I look at the unit. The price seems reasonable as well.

I just don’t know about the life if I run the unit at powers significantly below the nameplate rating.

Dave


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 12:38 am 
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Location: Long Island NY
Well, a 2KVA unit loaded to 40% would be about 7 amps. Maybe you could put some of your shop lights, soldering iron, shop radio, fan or heater, test equipment, etc., on it to load it down enough so it will respond well to line voltage fluctuations. Loading it will also help with the filtering. Or just go ahead and use it at lighter load. If you are going to shut it down when you are not at the bench its life will probably not be materially affected. The regulation might be as good but that won't matter for instruments that have built in regulators. It won't matter to a Hickok tube tester either, since it's a bridge circuit which is insensitive to minor voltage variations. (The requirement to set the line voltage to the mark on the meter is so the tube heaters are at a known and consistent level).

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 12:45 am 
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Be aware that old units (made before 1979) most likely have capacitors filled with oil containing PCB's and are therefore considered to be hazardous waste.


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 1:43 am 
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Location: Portland Oregon
Thanks for the replies.

That’s a good idea to have this connected to all my bench stuff, and then power up the bench with a flip of the switch. However, the more I think about it, the less I think I need this. I already have a nice toroidal isolation transformer connected to my autotransformer. I’m not sure if it is a good idea to have an isolation transformer powering another isolation transformer. It is a good note about the capacitors having PCB’s in them too.

The power conditioner has 4 capacitors on it: 30uF/330V electrolytic. The size is huge though, 3.5”longx1.5” diameter. I have no idea why those capacitors are so big. Maybe the technical support guy in the Philippines didn’t know how to read the manual. I can believe this, for it was readily apparent that I knew more about the item than he did. I have no idea why the capacitors are this big, physically.

Dave


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 6:01 am 
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Those are oil filled caps , they need to be large due to the power factor .It best to mount it vertical to a bench leg or wall unless it was made to sit on the floor .

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 6:59 am 
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Ferroresonant transformers are frequency sensitive so they need to be used at the frequency they are designed for. That isn't usually much of a problem when using commercial power, but it could be an issue if you contemplate running from a generator or other less than ideal source.

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 7:06 am 
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Joined: Mar Thu 29, 2018 3:41 am
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Location: Portland Oregon
I plan on running this on land power.

Is there anything special with the oil filled capacitors? Would a motor run capacitor work? I don’t think a motor start capacitor will work. Are the caps in this device high precision or ??? The Sola phone support specifically said they were electrolytic but the size isn’t consistent with 30 uF/330V. The size is very consistent with oil filled caps.

Dave


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 11:29 am 
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I picked one up at an auction with the intent to use it to power my bench. Then upon further consideration, I decided that any equipment requiring line voltage regulation to that precision already had precision regulators IN it, and this would just be redundant. Something else to fail, generate heat, and make noise.

So it's still sitting out in the warehouse. I did get a large variac to bring my 127V of AC line down to 110, but that's it. Never had a problem with line voltage .... no sagging, the occasional blip easily ignored by, so far, every piece of equipment I ether have or have worked on.

IMHO a solution looking for a problem. This is not what these things were designed to do .... they're better in an industrial setting where known surges and dips need to be filtered out, which, unless you live next door to a cement mixer factory, you'll probably never see.

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 4:37 pm 
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Location: Manchester, MI
Years ago I used to run one of these to supply my computer systems. That was back before UPSes were ubiquitous and you could buy a 1KW UPS with bad batteries for $50 or less.

I run all my sensitive stuff through a UPS now. Test equipment just gets plugged in to the wall.

They have their uses, but it's something of a niche these days.

A couple years back I did have the power line voltage go up to 265+V because of a utility fault. Putting 135V into some equipment might have been problematic so it could have been useful there. Monitor your line voltage from time to time and you should be fine.


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 4:51 pm 
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Joined: Mar Thu 06, 2014 6:01 pm
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TechyMechy, your same thoughts about sola constant voltage transformers and Hickok tube testers also occurred to me and I do have some actual practical experience that I can share. Sola transformers are fairly expensive new and so I managed to find and purchase several at various meets. They all had very NON-sinusoidal voltage waveforms. They were more like very sloppy square waves, more like the outputs from cheap 12VDC to 120AC volt inverters that are not specifically specified as having sine wave output. The Sola advertisements include some units specifically advertised as sine wave outputs and some not specified. I guess that the ones I have are the second variety.

One of the transformers was about the right size for my Hickok tube tester and seemed to work O.K except for the waveform. One day I inadvertently left it on with no load for a day or two and when I went to use it, it no longer worked. The problem was failure of a fairly large oil filled capacitor rated at 600 volts (non polarized). I replace it with an equivalent non polarized capacitor (600 volts also, but unknown composition, possible mylar or polystyrene) This also worked just fine until I accidentally left it on with no load for an extended period of time, after which it also failed. I eventually replace this with a 660 volt non-polarized capacitor used for the starting windings of AC motors and which also works just fine. So far it still works, but I have made a point of not leaving it on for any length of time without a load of some kind.

Chris108, the classical Hickok transconductance circuit, functionally, is not really a bridge circuit in the classical sense (Wheatstone bridge, for example) but IS insensitive to the applied voltage. However, the control grid test ac voltage for the tester is derived from a separate winding on the main transformer and will reflect changes in the primary voltage and so the measurement will be affected by any line voltage variations. That is why the better Hickok testers, like the 539A/B, allow the input voltage to the transformer to be adjusted before each measurement.

Mike


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 5:51 pm 
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Location: Portland Oregon
Thanks for the replies.

The Sola device I’m looking at doesn’t specifically say it produces a sin output, which probably means that the output is nasty. I really appreciate all of your input. I think that I’ll pass on this item.

It’s great to get input from you all and have this documented on the web.

Dave


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Thu 25, 2021 7:35 pm 
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Y'all reminded me of how dirty these type transformers can be. We had some large-ish ones powering an old TV production truck. They were so bad we had to add filters to get them back to something resembling a sine wave. I always wondered if we'd be just as well off getting rid of all that stuff and just hooking up directly to the incoming power.

This was back before all the equipment had well regulated power supplies, and some kind of regulation on the input was actually needed. So, damned if you do, damned if you don't I guess. Today, not really needed.

As noted, a smallish UPS would be way better.

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Fri 26, 2021 1:39 am 
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Motor starting capacitors are not appropriate for this application. They have a limited ON time spec, usually something like 30 seconds. A motor run capacitor is more in line with what is required.

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Fri 26, 2021 9:42 pm 
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Location: Oswego, NY, USA
If one uses an older Sola unit; it's a good idea to first make sure that none of its oil-filled capcitors contains any really toxic compounds, such as any PCB's. About 30 years ago I had one of the larger Sola units literally explode, smoke and fill an instrument room (walls, floor, ceiling, etc.) at my worksite, with smokey-colored slimey soot which was very high in several types of very toxic PCB's (we tested it in our college's environmental labs) and toxic combustion products. It required a special cleanup procedure. Unfortunately, often older oil-filled capacitors do not indicate which type of fill-oil is inside them; and from research I've done on it, few, if any, original capacitor manufacturers kept archived track of the oil's contents. Those days were pretty much prior to EPA, Osha, Ansi, etc. In other words, "if in doubt, throw it out".


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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Sat 27, 2021 3:18 am 
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Location: Long Island NY
I've had several of those transformers offered to me over the years free for the hauling, and I did not take them. It wasn't out of concern over PCB capacitors or anything like that. PCB capacitors were really excellent for power handling applications and I don't mind them a bit as long as they are not leaking. However as with any old things I test them and get them to the recycling center on hazardous materials collection day if they show signs of leakage, impending breakdown, or overheating. Modern silicone oil capacitors are available in the same shapes, sizes, and ratings. They are not cheap but they make it possible to replace any PCB cap that you don't want to keep around.

Nevertheless, I simply asked myself what a transformer like that was going to do for me before I burdened myself with something so heavy and clumsy. Power where I live is clean enough and reliable enough that dips and variations are minor and don't disturb what I am doing. I can adjust line voltage manually if I have to with a variac, I've got a couple of isolation transformers for working on stuff that's live, and none of my radios or test instruments are so sensitive to line voltage variations that I really have to worry about it. The sophisticated equipment already has internal regulation and the unsophisticated equipment doesn't really care. As others have pointed out, a desktop UPS is a better bet for anything containing a microprocessor. Bear in mind that many constant voltage transformers do not offer EMI shielding between input and output. Without that, EMI noise arriving on the primary is likely to couple right across to the secondary.

If the power in your area is really that bad, a Sola transformer might help, but if the power is pretty good, it is likely to turn into a white elephant.

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 Post subject: Re: Sola ferroresonant power conditioners
PostPosted: Nov Mon 29, 2021 4:54 am 
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Joined: Mar Thu 29, 2018 3:41 am
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Location: Portland Oregon
Hi All,

Thanks for the replies.

I decided not to get the Sola power conditioner. At first look, it seemed really cool. After these discussions and looking around the web, it really isn't very useful for the things I was hoping it would deliver (clean sin wave, constant power, isolation transformer). I have a nice isolation transformer now and a couple of auto transformers. That should get me bye. I'm just starting to make my instrument shelving unit and am planning how to power it, etc.

Dave


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