Replace MOVs at home in commercial Surge Protectors?

I read up on past threads about MOVs in surge protectors particularly the ones i nthis news group. However I have a question I do not
believe has been asked i nthe past.
I am a electric bass player and use a rack mount amp system. I ahve a Samson Powerbrite Pro7, which is basically a 1u rack mount unit with 6 switched outlets + 1 unswitched, with lights for the front and back that I find very handy. It is a 'power conditioner' which i come to understand means thats its an overpriced surge protector with MOVs. I bought it brand new 2 months ago.
Would replacing the MOV's every couple years be a viable alternative to replacing the unit, or ditching it for a simple strip that offers positive MOV circuit indication, or one of thos BrickWall or Zero Surge units that weigh a bit more and cost a lot more? Can MOV's be soldered in as replacements at home by someone with half-decent soldering skills? (i can mod computer motherboards fine) If so are there certain types of MOVs that are incompatible i nthe same protection circuit?
Thanks.
btw, does anyone know what power amps (such as QSC, Crown, Crest etc) use as their own surge protection? some say that their built in protection is better than pwoer conditioners, rendering them useful only for power distribution anyways.
-john
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The size of transient voltages 'possibly seen' by a plug-in protector occurs typically once every eight years; if in continuous use. If that transient damages a protector (sacrified itself), then protector was not protecting anything anyway; it was grossly undersized and typically overpriced. Grossly undersized is quite common with plug-in protectors (meaning transients too small to damage adjacent electronics still damage a grossly undersized protector).
Replacing internal MOVs is wishful thinking. For if transients were occurring so frequently as to require MOV replacement, then facility has far more serious electrical problems and too much damaged equipment. IOW location manager is trooping weekly to the hardware store to repeatedly replace 'transient damaged' appliances.
Don't worry about replacing internal MOVs. Worry more about getting proper grounding. Worry more about 120 volts rising to a constant 150 volts - which would damage your equipment and be totally ignored (too low to be seen) by every plug-in protector.
Some better power conditioners would protect 120 VAC equipment from a constant and destructive 150 VAC. No surge protector would provide such protection. Worse, that surge protector would act as if the voltage was 120 VAC - do nothing. Surge protector provides neither you nor your equipment a significant advantage - other than providing a single point ground for your electronics - exactly like a $3 power strip (plug mole).
"JohnK." wrote:

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this is a test msg sorry guys

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I agree. A "voltage regulating power conditioner" which will operate over wide AC input range (i.e., 75~150VAC) but keep output within 100~130VAC will be be more valuable than a power strip surge protector. AC mains voltage fluctuation is not common in USA (although during the NE Blackout in August of 2003, a NG user in New Jersey reported voltage swings of 79 to 145VAC which lasted for several hours !!!) but it is VERY COMMON in many underdeveloped countries in Central/South America, Asia & Africa. There, use of "voltage regulator" or "voltage stabilizer" is very widespread since electronic equipment lifetime can be as short as days or weeks when operated without a voltage regulator.
Even a simple isolation transformer based power conditioner (without voltage regulating function) can indirectly protect equipment from over-voltage if the power conditioner has built in fuse or circuit breaker. At 140VAC or higher, core saturation current might be enough to blow the input fuse or trip the breaker in the power conditioner - thus providing an indirect "Over-Voltage Shutdown" feature by accidient (since input fuse/breaker amperage value is chosen to protect the isolation transformer from overheating, but it also works as a protection against high voltage). Most UL listed / recognized isolation transformers also incorporate a thermal fuse which opens the primary winding when winding temperature goes above the thermostat setting which is also another indirect protective feature provided by a high-quality power conditioner with isolation tranformer as its main protective device.
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snipped-for-privacy@tsipower.com (Nam Paik) wrote in message

thanks to everyone who responded, i really appreciate it. i dont play at huge concerts or anything, mostly medium sized gigs, and my power conditioner has an accurate voltmeter and ammeter with a circuit breaker, with warning lights o nthe volt meter, but i have only seen the meter read at 120v with occasional dip to 117 volts, which seems to be well within the 10% range most people recommend, so i guess i ahve nothing to worry about for a while. and the MOVs in the unit are spec'ed to clamp at 250v's which seems to be pretty decent for my purposes. so it looks like i'll just use this thing for a few years, until i decide to get a voltage regulator.
-john
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The funny thing about voltage swings is the thing people worry about the most, their PC is probably the least affected by surges and sags. The switch mode power supply will work flawlessly over a wide range of input voltages. Way back in the olden days before switcher supplies, computers used a ferro-resonant transformer on the input that would automatically compensate for input variations. These had an additional winding that acted in conjunction with a capacitor to work like a buck/boost winding. These were big and expensive compared to a switcher so they quickly fell out of favor when fat power transistors got cheap.
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MOV's are tested for a surge. That is all. If you have had the maximum surge then they are probably toast. Eventually they will die even if they get little hits. I have not seen any unit made for residential use that has any circuitry that is verifiable that it really works on the state of the MOV's. The commercial units cost upward of $10k for the ones I have installed. Fusing is really not the answer either. Though some plug strips install circuit breakers, like they are fast enough to help. Over current no problem CB's work just fine.
As for replacing them. They are an UL listed assembly for a particular use. Replacing the MOV's which will be very hard will void the UL listing. The unit may not work correctly again anyway. Your statement of them being an "power conditioner" is erroneous. All an MOV will do is shunt a set voltage to ground at a particular threshold. Nothing more. If your really worried about surge protection then you should install one at the main and one at the point of use. IEEE on surge protection says you need 2 out of the 3 zones to make a system safer. The third zone is distribution and that is the utilities domain.
I have a surge protector at my incoming service panel and then plug strips at the point of use. I replace mine after each lightning season here in Arizona.
If your on the road playing, then do what a buddy of mine in Iowa did. He got his own isolation transformer, and connects it up and verifies his ground every show. Has not lost a piece of equipment in 8 years since he bought the 75 kva transformer. A low impedance to ground and a low ground impedance will help as well.
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75KVA isolation transformer must weigh over 1,000 lbs - how does he carry it around (unless it is permanently bolted into a bus or van?). It is like carrying a little substation. Are you sure about 75KVA? If the band needs 75KVA isolation transformer, then it means 75000VA divided by 120V = 625 amps.
How does a traveling band get access to 120VAC, 625A service (unless it is playing for 20,000 people in a stadium setting)?
Most 120V output sockets are fed by 15 amp breakers - which limits it to about 1.5KVA of continuous power output only (some hair dryers claim 1800 watt, but that's because it is used for a few minutes at a time - continuous use will trip the 15 amp breaker).
Larger 20/30/50 amp sockets are available only in factories or specially wired rooms. Most larger sockets are normally for 208 or 240VAC to power high-wattage machines such as copiers, heaters, dryers & large freezers, etc.
An isolation transformer with neutral to ground bonded secondary (output side) winding re-generates the "ideal" neutral measuring 0 (zero) volts with respect to earth ground. Of course, a low-impedance ground wire must be used to get the full benefit of such an isolation transformer. Multiple MOV's at the output of the isolation transformer also suppress line-to-neutral surge voltages above a certain threshold (typically 150VAC MOV's are used for 120VAC circuits) as well.
http://www.line-conditioner.com/White-Papers-On-AC-Power-Surge-Protection-And-International-Issues.htm will provide additional in-depth theory & methods of providing coordinated surge protection per IEC 61312.
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snipped

It is bolted to a frame with wheels, like his mixing board, the big amps and lighting boards. Have you set up many road shows? Not one piece of equipment comes out of the trucks with out wheels. I have set up shows like U2, Pink Floyd, The Stones, Phantom of the Opera, Miss Siagon. Usually you have less than 24 hours to set up, test, and preform and sometimes tear down. The 75 was a bargin and bigger than he needs.

Places he sets up are 3 phase distribution. His loads are single phase 120. The transformer feeds panels which have the circuit breakers in them. We got the panels from a used equipment peddler and I tested every circuit breaker with a breaker tester. Yes it is a bit more to lug about. Nothing more than what Floyd does. The last concert I set up, they wanted 200 amps 208v 3 phase for their chain hoists. They generated every volt and amp for their sound and lighting equipment. Some 2 meg, Rolls Royce 8 cylinder engines 1000 hp, and from the outside of the container you could not hear them. The container just vibrated. The welding cords were 15 sets of parallel 500 mcm some 200 feet long. Takes 10 guys to sting out each cable. They had the best voltage and hertz regulating equipment that I have ever seen. Real pros!

http://www.line-conditioner.com/White-Papers-On-AC-Power-Surge-Protection-And-International-Issues.htm
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He
ground
http://www.line-conditioner.com/White-Papers-On-AC-Power-Surge-Protection-An d-International-Issues.htm
With the peak voltage of a 120 VAC circuit being in the neighborhood of 170 V I would be surprised to find a 150 V MOV used. I expect that they would fail as soon as they are installed. In my experience, do to their sacrificial nature, and the likelihood of a short life with a low threshold voltage rating unit used, most mfg. of the cheap protectors use an MOV rated about 330 volts, or more for a 120 V circuit.
Louis-- ********************************************* Remove the two fish in address to respond
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On Sat, 24 Jan 2004 16:54:38 GMT, "Louis Bybee"

Which pretty much negates their protective purpose!
If I want spikes suppressed, I don't want the circuit waiting till the spike rises above 330 volts to get it. That is nearly double the peak voltage of the AC being "protected".
A poor choice for them. That makes their devices ONLY a lightning surge suppressor, and would provide next to zero conditioning on a "normal line" where "normal line" still needs substantial protection at well below 330 volts.
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