devices for surge protection

one thing I remember, and this was 25-30 years ago, before surge protectors were plentiful, that the article claimed that they only protected hot to neutral or some such and the article put in three MOVs across all three pairs of leads. when I made that I checked it with my cheap three LED electrical tester device and found something reversed. I rechecked my wiring and then plugged mine directly into the wall outlet and all was fine. the 6 outlet strip I had plugged into the wall and plugged my contraption in had reversed H/N. Notified FDA about it, at that time then covered product safety, and was hoping for a big recall but never heard more about it.
bumpy

Hi Mex,

Thanks for the information. Now I'll have to hunt for a "real" surge device. In the mean time the plug in unit may offer some small coverage (even if it is about as useful as a leaky pot).

Looking at what is inside the Progressive Industries product shows they only have MOV technology--and not a whole heck of a lot of it.



I would imagine that Surge Guard is no better--but I have not found a photo of the guts.

BTW the Sola Basic is a "stepped" unit which has 3 layers of boost ( switching in at 110, 100 and 90 volts) and one layer of buck (135 volts).

It switches fast enough to react to surge from the air conditioner. It is quite delightful to see the voltage go UP by 3 volts when the air cycles on. I've observed this on 15 amp, and 30 amp shore power supplies where I was the only user.

Voltage protection devices protect against "out of range" CONSTANT voltages. Many of these devices DISCONNECT the load from the source to achieve protection. SOME of these devices offer transient voltage spike protection via MOVs, TVS devices and Gas Discharge Tube devices.

VOLTAGE CORRECTION is a whole different ballgame. Correction of voltage can either buck or boost "incorrect" voltage. Some do it by automatically engaging or disengaging different transformer TAPS. These are STEPPED voltage correction devices. It is uncertain if Voltage Correction stepped devices contain transient voltage protection. But the are ALL autoformers with one leg of the transformer being common which makes them useless for INHERENT voltage transient protection. There are more variants of these stepped gizmos than Carter has Little Liver Pills. The consumer needs to read and understand what he is buying - what the voltage correction device will and will not do to correct high OR low constant voltage.

With a true ISOLATION TRANSFORMER the absolute maximum of transient voltage spikes is acheived. A square foot of circuit board loaded with GDT's, MOV's, and TVS devices cannot even approach the level of transient voltage protection of a true isolation transformer. But an isolation transformer alone does absolutely ZIP for voltage correction. My stack of 350 watt isolation transformers EACH unit weighs ELEVEN POUNDS. Imagine what a 3,000 watt isolation transformer would weigh!

FERRORESONANT Voltage Correction. Offers stepless plus and minus voltage correction usually 15% - 20% buck - boost. True transformer voltage spike protection. But they are transformers and will make a wealthy man slightly nauseous at the price - try $750.00 for a 750 watt unit, and thirty pounds. SOLA makes the best ferroresonant voltage correctors.

DISCRETE COMPONENTS. Metal Oxide Varistors MOVs are the standard of the industry. They can absorb goodly amounts of voltage spikes, but their reaction time sucks. MOVs can absorb just-so-many voltage spikes then they play possum. End of life. The more MOVs the longer the life. To be worthwhile only larger MOVs 20 mm in diameter should be be considered. MOVs must-absolutely-positively be connected ACROSS THE LINE, hot to neutral THEN MORE MOV's line to earth ground.

Transient Voltage Protectors TVSs are shaped like a little diode. They haave different ratings. I prefer TVS rated 180 volts BI-DIRECTIONAL. Voltage seems high but the devices have to deal with PEAK TO PEAK voltage ratings not merely Root Mean Square voltage values. A 180 volt TVS shunts voltage spikes within 4 NANOSECONDS. Billionths of a second reaction time. But unfortunately affordable TVS devices cannot deal with huge long lasting spikes. TVS will FAIL of overloaded for too long a time. This is where correctly rated MOVS step-in. The slow reacting MOV is supposed to react just in time to keep the TVS from overloading. I like the highest capacity TVS I can get my hands on - 1,500 watts. This rating of for a spike of microsecond duration. Try putting 1,500 watts through a TVS for 1/100ths second and you have a fried TVS. This is where the MOV comes in and lots and lots of MOVs offer a better safety net.

TVS must be bidirectional. They make UNIdirectional TVss but they are useless for royal-screwup-grade line voltage transients. Like MOVs, TVSs must be tripled line to neutral and line to earth ground for proper protection. This means NINE TVSs per circuit. Think about TOTAL CAPACITY! Line to neutral PLUS line to earth ground means transients have two paths to discharge. A wonderful backup indeed.

EACH TVS device should be protected with a 1 or two amp fuse because they can fail, and short, and overheat and well you can guess the rest :( With individual fuses they are ultra safe.

GAS DISCHARGE TUBE devices are the 600 pound gorilla. They react even slower than MOVs but my god do they ever handle gigantic transients. So GDT's are the final link and are useful for major line disturbances like distant lightning strikes. GDT can not short, but they can fail just like MOVs, when enough surges pass through them. GDT must also be connected line to neutral then line to earth ground and they are automatically bi-directional.

So proper component transient voltage protection should be a three step operation to achieve balance and good life.

All of the above is derived from actual real-life oscilloscope examination, and not from advertisements, catalogs, or spec sheets. The 3-component protection actually works. Pure MOV protection is sadly lacking, even using 100 MOVs. They just do NOT react fast enough.

The issue is to minimize the hammering and degradation of electronic components found everywhere in your rig. Pound an integrated circuit with enough 300 volt positive OR PEAK INVERSE VOLTAGE spikes and you will have a failed I.C. The same for diodes. Everything has a voltage rating. Limit the number of line peak voltage violations and you have happier components - read fewer failures.

This piece tore up my arthritic hands and fingers. I am going for an ice-bag and I will never repeat this. So copy and paste it or save it to disc. I will answer questions en breve but ouch, this is it. Thank you.

Hi Bumpyroad,

Here is a pdf article about series vs parallel surge installation.

http://www.emersonnetworkpower.com/documentation/en-us/brands/surgeprotection/documents/white%20papers/wp-30012_seriesvsparallel.pdf

From the article:

"If protection of equipment against destructive high energy transients is required, then a parallel connected device is likely to be the most logical solution."

Because I wanted to know how the Sola Basic was doing when I wired it, I put a 15 amp outlet in parallel to the input, and another 15 amp outlet in parallel to the output.

So I've used a device intended for a 15 amp outlet which I can place in parallel on the input for the Sola Basic. It's not perfect, but should afford me some surge control and offer the Sola some protection, too. It was not in my original idea for the unit but a (happy) afterthought.

Bumpyroad wrote:
years back I followed a pop science type of article and built a sp in a 6 outlet strip using MOVs and isolated the end outlet to plug in a printer and avoid any issues that could cause. don't think my set up was good for 30/50 amp however.
bumpy

years back I followed a pop science type of article and built a sp in a 6 outlet strip using MOVs and isolated the end outlet to plug in a printer and avoid any issues that could cause. don't think my set up was good for 30/50 amp however.
bumpy

It will help for surges. :)

Hi 2oldman,

Thanks for the help--I found out what I hoped to learn. Looks as if I can get some protection simply by plugging in an outlet type surge suppressor into one of the outlets I added to the Sola Basic autoformer.

The one I had to protect the fridge is actually "used up" so I guess it was a good thing to be doing.

2oldman wrote:
MOV surge

The full string turned out to be: mov surge protection circuit diagram

pianotuna wrote:
Hi 2oldman,What did you use as a search string?.

MOV surge

The full string turned out to be: mov surge protection circuit diagram

Hi 2oldman,

What did you use as a search string? Thanks in advance.

2oldman wrote:
Looks like a Mex question. Google shows schematics for such a device.