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Author Topic: Furman AR-1215 has MOVs... Preventative maintenance?  (Read 636 times)

frank kayser

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Furman AR-1215 has MOVs... Preventative maintenance?
« on: April 06, 2014, 11:48:41 pm »

Ugh.  Much to my dismay (but not surprise) the Furman AR-1215 contains MOVs.


"The AR-1215 also features power conditioning that is truly in a class by itself, thanks to the quantity, quality and configuration of the overvoltage suppression devices used. These include MOV's, high voltage inductors and capacitors, and precise high-inrush magnetic circuit breakers. This unique combination can safely divert large spikes as well as filter audible high frequency noise"
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Well, it has been discussed here a couple times before that MOVs are basically sacrificial components.  They "wear out".  They have a limited life that is largely based on how bad the power is that it is connected to.

Rather than dumping one (like one might a $15 power strip), it would seem prudent to perform some repair, or better yet, some preventative maintenance.

Can anyone hazard a guess as to how often one might go in and replace the MOVs?  Yeah, I know, depending on the service severity.

Any other components that I should consider sacrificial or with a limited lifespan?

thanks
frank

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Caleb Dick

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Re: Furman AR-1215 has MOVs... Preventative maintenance?
« Reply #1 on: April 07, 2014, 08:23:59 am »

I've heard, but am not an EE, that today it's more about the overall design, not simply MOV's = bad.  I read a white paper recently, forgot which manufacturer, that put my mind a lot more at ease about modern, higher cost power protection that contains MOV components.

Typed on a virtual keyboard. 

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TJ (Tom) Cornish

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Re: Furman AR-1215 has MOVs... Preventative maintenance?
« Reply #2 on: April 07, 2014, 09:06:22 am »

Ugh.  Much to my dismay (but not surprise) the Furman AR-1215 contains MOVs.


"The AR-1215 also features power conditioning that is truly in a class by itself, thanks to the quantity, quality and configuration of the overvoltage suppression devices used. These include MOV's, high voltage inductors and capacitors, and precise high-inrush magnetic circuit breakers. This unique combination can safely divert large spikes as well as filter audible high frequency noise"
[/size]
Well, it has been discussed here a couple times before that MOVs are basically sacrificial components.  They "wear out".  They have a limited life that is largely based on how bad the power is that it is connected to.

Rather than dumping one (like one might a $15 power strip), it would seem prudent to perform some repair, or better yet, some preventative maintenance.

Can anyone hazard a guess as to how often one might go in and replace the MOVs?  Yeah, I know, depending on the service severity.

Any other components that I should consider sacrificial or with a limited lifespan?

thanks
frank
MOVs can be tested in a rudimentary way with a resistance measurement across the leads (unplug the device before testing, of course).  If the measured resistance is in the meg-ohms range, the MOV is likely good, at least from a leakage perspective, however the MOV may have failed open (this is not likely unless something significant happened that you would likely know about).  Fully-testing MOVs requires a current-limited high-voltage supply to see that they actually do clamp at the required voltage.

From a practical standpoint, if you're using this for portable work and it won't remain plugged in all the time, the chance of MOV damage is pretty low, and the protection that MOVs give is pretty minimal.   I wouldn't worry about it unless you're having GFCI tripping problems or getting system noise.  If you are having problems, since MOVs don't really do much, you can clip them, and though you're out some theoretical surge protection, the voltage regulation function of your AR will still work, and they are still nice power strips.

For installs, MOVs may indeed take hits, and they gradually break down.  There isn't a perfect rule of thumb for device lifespan, because the breakdown is based solely on the surges they have eaten.  If you're in Florida in the thunderstorm belt, they will need replacement a lot more often than in Arizona.

If you really want maintenance free protection, SurgeX is your answer.  Be prepared to mortgage your house to buy them.
« Last Edit: April 07, 2014, 11:03:15 am by TJ (Tom) Cornish »
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TJ (Tom) Cornish

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Re: Furman AR-1215 has MOVs... Preventative maintenance?
« Reply #3 on: April 07, 2014, 09:15:01 am »

I've heard, but am not an EE, that today it's more about the overall design, not simply MOV's = bad.  I read a white paper recently, forgot which manufacturer, that put my mind a lot more at ease about modern, higher cost power protection that contains MOV components.

Typed on a virtual keyboard.
You were presumably reading the Furman SMP whitepaper: http://www.furmansound.com/page.php?div=01&id=SMP

There was a discussion of this a few years ago (I think I started the thread).  I have not spent any significant time investigating since then, and have not vetted their claims one way or the other.  An interesting note - they claim their tech is designed to not degrade over time, however they also say the MOV is actively used to absorb energy.  On the surface, that seems contradictory.
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frank kayser

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Re: Furman AR-1215 has MOVs... Preventative maintenance?
« Reply #4 on: April 07, 2014, 09:52:15 am »

You were presumably reading the Furman SMP whitepaper: http://www.furmansound.com/page.php?div=01&id=SMP

There was a discussion of this a few years ago (I think I started the thread).  I have not spent any significant time investigating since then, and have not vetted their claims one way or the other.  An interesting note - they claim their tech is designed to not degrade over time, however they also say the MOV is actively used to absorb energy.  On the surface, that seems contradictory.


Actually TJ, I hadn't read the paper - interesting - of course a sales pitch - a "substantive" one at that.  It does seem contradictory... I was considering an additional unit I found used. Your rudimentary check could be helpful - my "experience" is that a MOV that has failed will show some external signs from heat - discoloration, cracking, discoloration of surrounding mounting or components, etc.  Granted, not always, and your test may show one that is near failure.   


Your logic of using as a portable vs. installed unit makes good sense (and offers some relief).  Since my existing unit is not exhibiting any of the faults you outlined, I feel even better. 


As far as a Surgex, I don't have enough equity in my home...


 
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TJ (Tom) Cornish

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Re: Furman AR-1215 has MOVs... Preventative maintenance?
« Reply #5 on: April 07, 2014, 10:27:04 am »


Actually TJ, I hadn't read the paper - interesting - of course a sales pitch - a "substantive" one at that.  It does seem contradictory... I was considering an additional unit I found used. Your rudimentary check could be helpful - my "experience" is that a MOV that has failed will show some external signs from heat - discoloration, cracking, discoloration of surrounding mounting or components, etc.  Granted, not always, and your test may show one that is near failure.   


Your logic of using as a portable vs. installed unit makes good sense (and offers some relief).  Since my existing unit is not exhibiting any of the faults you outlined, I feel even better. 


As far as a Surgex, I don't have enough equity in my home...
I left out a sentence in my earlier reply - since MOVs provide relatively little protection, for portable use, you can simply clip them and solve any noise issues that way.

I have several rack mount power conditioners - an old Furman LED ladder one that the MOVs did start to fail on - ground contamination resulting in noise.  I clipped the MOVs and am still using it.

I have one SurgeX, and one Furman SMP.  I actually like the Furman SMP - they do seem to fill the middle of the road in a reasonable way between garbage MOV-only stuff and the space-grade-priced SurgeX stuff.

My big beef about the Furman SMP is that the meter is switched - I want to know the voltage of the circuit BEFORE I switch it on and risk my gear, not after (yes I know this is not a complete receptacle testing procedure).
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frank kayser

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Re: Furman AR-1215 has MOVs... Preventative maintenance?
« Reply #6 on: April 07, 2014, 06:00:52 pm »

I left out a sentence in my earlier reply - since MOVs provide relatively little protection, for portable use, you can simply clip them and solve any noise issues that way.

I have several rack mount power conditioners - an old Furman LED ladder one that the MOVs did start to fail on - ground contamination resulting in noise.  I clipped the MOVs and am still using it.

I have one SurgeX, and one Furman SMP.  I actually like the Furman SMP - they do seem to fill the middle of the road in a reasonable way between garbage MOV-only stuff and the space-grade-priced SurgeX stuff.

My big beef about the Furman SMP is that the meter is switched - I want to know the voltage of the circuit BEFORE I switch it on and risk my gear, not after (yes I know this is not a complete receptacle testing procedure).


Good note about clipping out the MOVs. 
I also would like the meter to show input voltage before I flip the switch.  The Furman AR-1215's meter is also switched, and shows just regulated output voltage.    Unless there's a fault, it really shows absolutely nothing.  Minor complaint, but could be so much better.  And no, not a complete receptacle test procedure by any means, but ...
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