surge protection on washer??

Page 2 of 4  
On 1/26/2014 12:37 PM, Ralph Mowery wrote:

There is no reason to slow the rise time, at least for MOVs.
Inductance stores a surge, it does not dissipate it.
If you had identical MOVs in parallel they would equally share the surge and the cumulative rating would increase (look at MOV curves for surge amps versus number of surges). With an inductance between they do not equally share the surge and you are, in effect, lowering the cumulative rating.
Manufacturers do not put inductance between MOVs. They will tell you not to daisy-chain plug-in protectors. And it is a violation of UL standards for plug-strips (which is one of the listings for most plug-in protectors).
In a building, the inductance between a service panel and plug-in protectors works much different than the inductance for wiring between 2 daisy-chained plug-in protectors.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, January 27, 2014 11:47:07 AM UTC-5, bud-- wrote:

How is that? inductance is inductance. And how about the MOVs inside an appliance? They are a similar distance from a second cord type surge protector if you had two in series.
I'm not disagreing that the amount of surge current the first surge strip would possibly take could be larger than the subsequent one. And I'm not disputing that UL says you shoudn't daisy chain power strips, but I think that is a separate issue, ie they don't want dummies plugging 5 things in one strip, then another 5 in the next one.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Could be one of those UL things for dummies. Not that I did it for protection, but at my computer desk there is a surge supressor strip behind it that has my cable modem and router pluged into it. It stays on all the time. Pluged into that strip is another one that is about a foot square with a switch on the frount and the outlets on the back. It is mostly empty space inside but makes a base for things to sit on. I use the switch on it for the compute, monitor and printer. It may not meet the stupid UL rules but is safe as the current drawn is not very much.
At work there was a big stink about some battery chargers for the handy talkies. There was about 3 strips plugged into each other. They all had the wall wart cubes on them. I am sure there was not a 10 amp load on the whole system if all the chargers were putting out the maximum charge. Safety department saw that and made them move the strips to seperate outlets.
--
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2014 11:07 AM, snipped-for-privacy@optonline.net wrote:

A service panel protector is exposed to whatever comes in on the power service wires. That is, for practical purposed, up to 10,000A surge current. The protector will lower the surge voltage to a reasonable level.
Suppose there is no service panel protector and there is a large surge. At about 6kV between the busbars and enclosure there is arc-over. The voltage across the established arc is hundreds of volts. Since the enclosure is connected to the earthing system, most of the surge energy is dumped to earth. And since the building ground and neutral are connected the surge at that point is all "normal" mode (between hot and ground/neutral).
The inductance of the branch circuit for the very short duration surge caused by lightning then greatly reduces the surge current that can reach a plug-in protector. That is true whether there is a service panel protector or not. The branch circuit inductance is an intrinsic part of the protection provided by a plug-in protector**. (If you have a very short branch circuit you should have higher ratings for a plug-in protector.)
When daisy-chaining plug-in protectors, the inductance between the protectors does not have the same major effect.
But what if the L-N MOV conducts in the first protector and the L-G MOV conducts in the second protector. There is voltage drop across the inductance of the hot wire between protectors that results in a higher L-N voltage at the protected equipment. In a service panel, the lead length is very important (60 volts drop for 6 inches of lead and 500A surge current - from the IEEE surge guide). Is it a problem in a 6 ft power cord? I don't see a reason to find out.
** For plug-in protectors "if included in the manufacturer's instructions the ... connections shall be a minimum of 30 ft of conductor distance from the service...." (2011 NEC 285.25)

Ideally I would rather have all surge protection that is at the equipment at a single location. For interconnected equipment that would have to be common to all the equipment. But I manufacturers include internal protection for sensitive' equipment since users may not add external protection. It is a necessary compromise.
I don't see a reason to add another layer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, January 27, 2014 2:25:22 PM UTC-5, bud-- wrote:

Sure, it's not the same magnitude of effect, but it's still inductance causing a difference.

It would seem to me that there is a lower voltage at the protected eqpt, because part of the voltage drop is between the protectors.
1000 - 100 = 900
And if there were no second surge protector, the eqpt would see the full 1000V. What works on 15 ft of wire also works on 3 ft of wire, just to a differing extent.
In a service panel, the lead

Now you;re sounding like Wtom how says that without a direct connection to earth, no protection is possible. If 6 ft is a problem for one surge protector, then it's a problem for another one and it's a problem for the surge protection in the eqpt itself, which any with electronics have. How can that MOV in the TV work, but a second surge protector after the first is a problem?

But that surge protection is working with a whole house, a plug-on, two plug-ins, whatever is before it. And you haven't answered the question as to how that MOV in the appliance is different than adding a second surge protector before it.

If I already had two surge protectors that were of equal rating that I had no other use for, I see nothing in the physics that says daisychaining them to protect a $1000 TV is a bad idea.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Where is Wtom when we need him. :-)
--
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/28/2014 11:35 AM, snipped-for-privacy@optonline.net wrote:

So make it H-N at the first protector. That lifts N toward H. Then N-G at the second. That pulls the N at the 2nd protector away from the N at the 1st and adds to the H-N surge seen at the protected equipment. It also increases the voltage between H and signal wires referenced to G.
With no service panel protector, the voltage at the panel could be up to around 6kV. With a H-N MOV the voltage on both H and N wires at the protector could be around 3kV above the ground at the panel. (The protector still protects because, if connected correctly, the voltage between all wires going to the protected equipment is safe for the protected equipment.)

Not at all. Plug-in protectors, wired correctly, provide protection.

As I wrote below protection in the connected electronics is a necessary compromise. (And the circuits for electronic equipment I have seen do not have N-G MOVs.)

I did answer it above. It is a necessary compromise.
(And service panel is different from downstream protectors.)
Using 2 plug-in protectors is an unnecessary compromise. What manufacturer allows daisy-chaining? What manufacturer intentionally adds inductance between paralleled MOVs?

You can, of course, do what you want. Don't expect that either manufacturer will honor a warranty.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tuesday, January 28, 2014 1:57:57 PM UTC-5, bud-- wrote:

Are all these surge protectors defective? They all have similar MOVs and they all should be conducting when the clamping voltage is exceeded.

But they are there and apparently bad things aren't happening from having a second set of MOVs 6 ft further down the appliance cord from a plug-in. So, I don't see it happening with a daisy chained external surge protector either.

Is Polyphaser adding inductance between MOVs good enough?
http://blog.aa6e.net/2005/03/polyphaser-pldo.html
Or look at all these schematics:
https://www.google.com/search?q=images+surge+protector+schematic&tbm=isch&tbo=u&source=univ&sa=X&ei=-AzpUp3pErPlsAS22IFo&ved DUQsAQ&biw08&bihw8
How about Electronic Design News:
http://www.edn.com/design/components-and-packaging/4413082/A-circuit-simplification-for-AC-power-supply-surge-protection-devices

I think the surge protection warranties are a joke. I've seen enough reports of people trying to collect on the alleged "protected equipment" warranties. You try to collect, send the surge protector in to them and then typical response is "The surge event exceeded the design limits of the device. It's not covered"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/29/2014 8:21 AM, snipped-for-privacy@optonline.net wrote:

UL let thorough ratings are in gross steps - I think the bottom 2 are 330 and 400V. If a protector tests with 250 actual let through volts it has a UL rating of 330. If it tests with a let through voltage of 320 it also has a UL rating of 330V.
And even if you have 2 MOVs with the same part number from the same manufacturer the actual ratings can be quite different - they are not precision parts. (If a manufacturer wants to parallel them they should be matched - same manufacturing lot may be enough.)
If you parallel protectors with 6 ft of lead between you are setting up a science experiment with many unknown variables with an unknown time when the experiment will run.

So lets use 3 sets of MOVs with 2 sets of inductance in between. More unknown variables for the science experiment.
Manufacturers do not like this kind of science experiment and do not allow paralleling of plug-in protectors.

Actually engineered with inductance between MOVs. It is likely to be used by hams with antennas that are likely to be hit by lightning. Very high surge ratings. What a typical example.

Paging through it (without a magnifying glass) I saw 4. 2 uses GDTs - covered elsewhere 2 have no explanation where the circuit is from or of why inductance does anything useful

Was already posted by Ralph. "The circuits all use gas discharge tubes. Far as I know those are not used in the power circuits of plug-in protectors, and I haven't heard of them being used in power circuits of electronics. Gas discharge tubes have a short delay until they operate - the gas has to ionize. Inductors may or may not make sense with gas discharge tubes. The article is probably aimed at Europe."

If the protector is from a reputable company I don't. They want to protect their reputation.
Because the energy at a plug-in protector is small (covered elsewhere) failures are unlikely.

I have never heard that one. I have seen a couple complaints where the protector was not wired correctly (all wires to a set of protected equipment must pass through the protector), and that is likely the cause of most equipment damage. I suspect the manufacturers want to see damage within the protector to indicate a surge got through. They also want evidence that there was lightning (or another event).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wednesday, January 29, 2014 3:04:00 PM UTC-5, bud-- wrote:

Just like the experiment you have with a surge protector at the panel, followed by wire that could be anywhere from 2ft to a 100+ ft, followed by a plug-in surge protector, followed by 6 ft of cord, followed by the surge protectors in the appliance.

Per the above, similar to the science experiment you have with varying wire lengths, varying types of plug-in surge protectors, another unknown length of wire, then surge protectors in the appliance.

What manufacturers like or don't like doesn't change the physics.

Well, that's what you asked for, wasn't it? Surge protectors that had inductance designed in between two MOVs? The very inductance you said was a bad thing? Polyphaser has that design. It exists. QED
It is likely to be

Good grief. You asked for an example. I gave you one from polyphaser, a well respected manufacturer. Ralph and I showed you an EDN article that specifically shows inductors used between MOVs. Polyphaser has exactly that design. Now what's the problem? The Polyphaser is too good of a surge protector?
Also noted is that your position is kind of like John Kerry's I voted against the war after I voted for it. You claim that having a panel surge protector followed by who knows what length of wire, then who knows what kind of plug-ins is great because the inductance helps. But then if you put one set of MOVs after another separated by 3 or 6 ft of wire, that inductance is bad.

Ask Polyphaser. That'a about as real and credible as it gets. Even Wtom likes Polyphaser.

Assuming that's true, electrons work differently in Europe?

I've seen plenty of people report that they couldn't get a dime. These companies sell millions of units. Not paying off on a few thousand who actually put in a claim isn't going to amount to anything. And it's easy to do. The most frequent response I see people bitching about is that the company simply claims the surge exceeded the devices rating. How are you going to prove that it didn;t?

And how exactly does one prove to the manufacturer that you had it wired correctly? There are plenty of reports from people trying to get paid on these equipment claims and they get nowhere. Not hard to find.
I

Yeah, and then they say the lightning exceeded the rating of the device. Now what? Or they say they want the TV or whatever shipped to them for analysis. Are you gonna pay to ship a three year old TV that cost $500 to them, so they can examine it on the hope that they will pay off on it? And if they do, they typically pay the current value of the TV. What's the current market value of a 3 year old TV? So, you can spend a lot of time spinning wheels and *maybe* you get a pittance, if you're lucky.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/29/2014 5:38 PM, snipped-for-privacy@optonline.net wrote:

<redundant stuff deleted>

Below: "I suspect..."

I have doubts that a company like SquareD or Leviton would not honor warranties.
People have a habit of thinking "it was a surge" when their TV dies. If companies paid without investigating they would be out of business.

I don't know what that means and have never seen it in many threads about surges.

What I have read is the TV is taken to a service center, which is usually local.

But when you crashed your 1986 Ford last week insurance payed the value of a new car.

Maybe you should get one without a warrantee.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, January 31, 2014 5:26:07 PM UTC-5, bud-- wrote:

Warranties that are typical of many manufacturers have plenty of terms that give them plenty of reasons to not honor the warranty. From the stories I've read online, the two classic responses are:
1 - We only pay for the protected eqpt if the surge protector show signs of damage from a surge and your surge protector shows no such damage.
2 - Your surge protector was damaged by a surge that exceeded it's specification, so we won't pay.
Another tactic is to require you to file a claim with your own homeowner's insurance. More BS, because homeowner's insurance typically isn't going to cover a $500 TV, but the insurance company may raise your rates. Would you put in a claim for a three year old TV that cost $500? But that's what they want you to do, one more hoop to make you go away. And then if you're lucky and jump through all the hoops, they give you $100.

That's precisely part of the whole point, that it's often not practical or impossible to "prove" the claim. Some of the warranties include that the investigation includes you shipping the damaged TV to them for analysis. How practical is that for the typical claim?

It means every surge protector has a maximum rating and if the one you sent back has blown up components, then they can say the surge exceeded the max rating and the claim is denied. And as you pointed out, the catch 22 is that they can also deny it if there is no evidence of a surge damaging the protector. So, it has to be like Goldy Locks. If they say that the surge is too big or didn't exist, then they don't pay.

I wouldn't have collision insurance on a 1986 Ford for two reasons. First, financially, the cost of the insurance makes no sense. If you had $3000 worth of damage, they will pay you the book value of the car, $500. The other reason applies to the surge protector warranties. The hoops you'd have to go through to collect and what you *might* get if it;s decided in your favor, means in many cases, it's not practical and I would not rely on collecting a dime.

A protected eqot warranty or lack thereof wouldn't make much of a difference to me. And I sure wouldn't have much faith that I would ever be able to collect anything on one that did.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/31/2014 8:19 PM, snipped-for-privacy@optonline.net wrote:

I don't see a problems with that. I don't know of another way manufacturers can determine damage was actually due to a protector problem.

Looking at many threads on surge protection I have never seen that, and I have major doubts.
But suppose a MOV exceeded its ratings. The normal failure mode is to conduct at normal voltages causing heat (which will be after the surge is over). Thermal protectors, included in UL 1449 listed protectors since at least 1998, disconnect the overheating MOV.
The IEEE surge guide goes on at length that the protected equipment can be connected across the incoming line, or across the MOV. In the second case, disconnecting a failed MOV also disconnects the protected equipment and it is not exposed. According to the IEEE surge guide, UL now requires that protectors that do not disconnect the protected equipment be labeled as such.
I expect that all protectors with warranties disconnect the protected equipment, so MOV failure should not be an issue.
And I really think companies like SquareD and Leviton will honor warranties.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, January 27, 2014 2:25:22 PM UTC-5, bud-- wrote:

That's kind of my point. If there's only 3 ft of wire between the MOV's, then there isn't going to be a lot of inductance. Again, I'm not saying that if you had two of the same MOVs separated by that additional 3 ft that it would be as good as having one that was twice the rating. But I don't see it as being bad either. The surge would probably get split between them, but not 50-50. I wouldn't go out and buy two surge protectors to use that way. But if I had two sitting around I don't see the downside in the physics to daisy chaining them.

The MOV will all be conducting if the clamping voltage is exceeded. And I don't see how part of the voltage drop being across the inductance of the hot wire in the cord is a bad thing. If the voltage drop is across the inductance of the cord, then it's not across the appliance. It would seem you could make exactly the same case for the interaction between a panel protector and a plug-in, or between the plug-in and the internal MOV's in the appliance. All of those are separated by wire with inductance.
In a service panel, the lead

Well, yeah because they are dealing with potentially 10K amps and the shorter the path to ground, the less impedance. But at the typical appliance you already typically have 25 - 100 ft of wire to deal with, then an appliance cord that's 6 ft, then surge protection in the appliance.
If it's a problem for a second surge protector at the end of a 6ft cord, why isn't it a problem for one surge protector followed by the MOVs that are at the end of the 6 ft appliance cord?

Except I've never seen that in any surge protector manufacturer's instructions. Have you?

Yes, but the point is, it's in fact more surge protection, MOVs, situated 6 ft down the cord from a plug-in protector. If that doesn't result in bad things happening, I don't see why a second plug-in daisy chained that can handle substantially more surge current will.

From a practical standpoint, I agree. But I don't see anything in the physics that says it's a bad thing either.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/29/2014 7:51 AM, snipped-for-privacy@optonline.net wrote:

The numbers quoted above are for 500A surge current, not 10k.
And it is not the path to ground (that is someone eases fetish). It is the path between H-N, H-G and N-G, which determines the effective clamp voltage between those wires.

Which greatly lowers the surge current that can reach the protectors. (Below 500A?)

Which can increase the clamping voltage seen at the protected load.

So use 3 sets of MOVs with 2 sets of inductance between.
Electronics is likely to only have a MOV from H-N with an unknown clamp voltage and lower surge amp rating.

Plug-in protectors are "Type 3 SPDs" and I believe testing is done with 10 ft of branch circuit wiring. I have seen a 10 ft requirement in Leviton literature. It may also be part of UL1449 3ed (2004).

So do whatever you want.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The better ones do. Here is one example.
http://www.edn.com/design/components-and-packaging/4413082/A-circuit-simplification-for-AC-power-supply-surge-protection-devices
.
I did not make it clear abou the inductance. Becuse many surges will have a very steep rise time, the inductance acts similar to a resistor and prevents some of the surge from getting past it. Much like an RF choke in a radio circuit.
--
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2014 11:14 AM, Ralph Mowery wrote:

Why are those "better ones"?
The circuits all use gas discharge tubes. Far as I know those are not used in the power circuits of plug-in protectors, and I haven't heard of them being used in power circuits of electronics. Gas discharge tubes have a short delay until they operate - the gas has to ionize. Inductors may or may not make sense with gas discharge tubes.
The article is probably aimed at Europe.

Far as I know, the inductors in plug-in protectors in the US are for noise filtering (and I am not convinced that does anything useful). MOVs are faster than surges and inductors are not necessary for protection.
An inductor is likely to lower the rise time and lengthen the surge.
I don't know of MOV based plug-in protectors that use multiple MOVs with inductors between them (in the US).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Then read this and learn what the inductors are for in the beter surge protectors. http://www.eetindia.co.in/ARTICLES/2003MAY/A/2003MAY29_POW_AN9.PDF?SOURCES=DOWNLOAD
This one is from a company in the US.
The inductors can provide two functions. One is the RFI protection that keeps the 'trash' from the device from going back to the power line in normal operation. When a surge comes on the line it has another function.

--
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 1/27/2014 2:10 PM, Ralph Mowery wrote:

Why are those "better"? And why were the circuits in your previous post "better ones"?

Interesting that the link is from ee times - india.
The app note is from Littelfuse. It is for using gas discharge tubes in combination with MOVs. As I wrote previously, GDTs have a time delay because the gas has to ionize. The app note uses MOVs to protect during the time delay so GDTs can be used. Coincidentally Littelfuse makes GDTs.
From my last post - "far as I know [GDTs] are not used in the power circuits of plug-in protectors, and I haven't heard of them being used in power circuits of electronics."
According to the IEEE surge guide (which has been linked to here often), "the vast majority (>90%) of both hard-wired and plug-in protectors use MOVs to perform the voltage-limiting function. In most AC protectors, they are the only significant voltage limiters." MOVs are so widespread because they have high energy dissipation capacity in a small package at relatively low cost.
And from the Littelfuse app note: "The clamp-type devices [MOVs] have faster response times but are limited in their current handling ability because most of the energy of the transient must be dissipated by the clamping device." Most of the energy of the transient is _not_ absorbed by the MOV. As I have often posted, an investigation by the surge expert at the NIST found the energy that was absorbed at a MOV in a plug-in protector was surprisingly small - 35 joules max. In 13 of 15 cases it was 1 joule or less. The service wire surges were up to 10,000A, the maximum with any reasonable probability of occurring. And the largest energy at the MOV was not caused by the largest surges. Protectors with ratings far larger than 35 joules are readily available.

Noise filters are likely real useful in electronic equipment.
I am not convinced they do anything useful in plug-in protectors.

That is if you are using Littelfuse GDTs for protection, backed up by MOVs for the hole in GDT protection.
--------------------------- I would not daisy-chain plug-in protectors. The inductance between the protectors can work to your disadvantage. And no manufacturers I know of allows daisy-chaining.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I ment to post this link. http://www.littelfuse.com/data/en/application_notes/ec640.pdf
To understand how inductors work you need to understand the rise time and dv/dt.
--
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.