High end UPS for Expensive audio eequipments

@westom

Please describe which power supply design you are talking about? I haven’t done an exhaustive study, but after examining say, two dozen devices, including DAC’s, mostly amplifiers and preamps, headphone amps, etc., I have yet to see a single one that included "robust" surge protection. I will occasionally see UL listed "noise" filters which are not the same thing, so I really would like to see what you are talking about. The one location where I have seen consistently and extensive use of surge protection is in PC power supplies.

Westom, you are also misinformed about the latest surge technology. Series mode does not connect to ground. They use a very large coil (compared to most surge protectors) instead which becomes the high voltage point in the circuit, and dissipate surge energy as heat instead of current. Their UL listing proves the effectiveness, and the normal "joule" rating becomes irrelevant.

A ground circuit is not needed in an SMP, so the quality of the ground for this application is no more needed than for GFCI circuits. As for your parallel devices being "harmless" we had about 2 dozen of these "harmless" protection devices (MOV’s?) in surge strips flame when a glitch in the local switching station occurred. They did protect the systems attached, but the speed of the surge was a lot slower than lightning.

But the cost / value item is another issue. I find the Furman devices inexpensive enough, and my gear precious enough to worry about it.

Best,


Erik

westom

Power supplies already contain robust protection that makes most surges (including mythical ones from household appliances) irrelevant.

That's absurd. Few devices contain serious protection against power surges. And I'm not sure why you call appliance surges "mythical" when they can be both heard and measured.

An effective protector must connect low impedance (ie less than 10 feet) to single point earth ground ... Effective protectors (as installed for free on phone, satellite dish, and TV cable) always have a low impedance connection to single point earth ground. 

That's not only mistaken, but typically a violation of current code, at least in the US. Multiple ground rods are now required at a service entrance and if that's not part of an installation now, it will almost certainly be required if the service is ever upgraded. Also, the length of the connection to the ground rod is not usually the determining factor of the safety ground's impedance - that's established by soil conditions. Moreover, a household's ground isn't really through those grounding rods - those are just the safety grounds. The real ground is back through the utility connection - as required by code - unless you have some type of electric problem or malfunction.

@cleeds I think @westom is talking about how traditional surge protection works, which is to short over-voltages to ground.

I should note, just for being complete, that the series-mode protection is (by design) a low-pass filter so it works great on power lines but if applied to Cable TV or satellite signals it would block the signal too, so it's application is limited to AC line protection.

Because of this, units for home have multiple filtering "modes" for POTS (copper phone), LAN, Cable, etc. even if they use series-mode for power.

Best,


Erik

>  Please describe which power supply design you are talking about?
Long before PCs existed, international design standards required 120 volt electronic to withstand up to 600 volts without damage.  Today's PSU are more robust.  I recently saw a Seasonic spec that defined protection up to 1800 volts.  

Appliances already have robust protection.  To know otherwise means a denial comes with numbers.

Series mode filter is not a surge protector.  Lately those manufacturers have hyped a filter as a protector. Hyping it in sales brochures as a surge protector means a massive profit increase.  As naive consumers spend $hundreds only because they are told they need it.  How many consumers now believe a UPS does surge protection?  Most.  Subjective lies (rebranding it as a surge protector) can massively increase profits since so many ignore numbers.  Furman is another example of big hype and near zero protection.  Your reply should include Furman numbers that define protection.  Good luck finding them.

How many joules does that series mode protector absorb?  About 600.  A 600 joule surge is easily converted by electronic power supplies into rock stable, low DC voltages to safety power semiconductors.   That series mode protector is protecting only from something that is not destructive.  Otherwise you would have posted numbers for it rather than a subjective (advertising) expression.

Nobody said an earth ground is needed for a SMSP.   Where did that come from?

MOVs that flame mean a protector was grossly undersized.  Designed in violation of what MOV manufacturers require. That catastrophic failure must never happen.  MOV datasheets make that obvious.  Plug-in protectors typically claim to protect only from near zero surges (ie 600 joules).  Contain circuits to disconnect protectors parts as fast as possible.  And leave that surge still connected to equipment.  Due to superior protection, equipment protects itself from tiny surges that destroy or flame a near zero protector.

Effective protection is for surges that might overwhelm robust protection already inside every appliance.  Facilities that cannot have damage properly earth a 'whole house' solution.  It costs tens or 100 times less money.

A surge too tiny to overwhelm protection inside equipment turned a near zero (ineffective) protector into flames.  Fires are created by near zero joule protectors.  APC recently admitted some 15 million protectors must be removed immediately due to fire.

And finally, UL says nothing about hardware protection.  UL is only and completely about protection of human life.  Who is the UL?  National Fire Protection Association.  An ineffective (near zero) protector can still be UL Listed.  UL says nothing about protecting appliances.  Never cite UL as proof of effective surge protection.

Once learned, those many facts expose myths that promote obscenely profitable and near zero protectors.

>  Also, the length of the connection to the ground rod is not usually the determining factor of the safety ground's impedance - that's established by soil conditions. 

You have confused resistance with impedance.  Wire length, sharp bends, metallic conduit, etc can significantly increase impedance and not change resistance.

From Jensen Transformers' "Understanding, Finding, & Eliminating Ground Loops in Audio & Videa Systems":
> An EARTH ground is one actually connected to the earth and is necessary for LIGHTNING protection.

From Mike Holts  "Grounding vs Bonding":
>An effective, low-impedance ground path is critical for the successful operation of an SPD. ... Therefore, an evaluation of the service entrance grounding system at the time of the SPD installation is very important.

From Dr Standler's book "Protection of Electronic Circuits from Overvoltage":
> It is essential that every arrester be connected to ground, because the charge in a lightning strike flows to ground. However, providing a low-impedance connection to ground is one of the most difficult practical problems in installing a surge arrester.

From George Kauffman in Electrical Engineering Times:
> Another aspect of impedance ... of a wire is predominately related to
> its length and weakly related to its diameter. ... The length of the
> cable increases the impedance dramatically.

From CRITEC's Technical Note TNCR019:
> The rule of thumb is each foot of wiring adds an additional 50-200V of let-through voltage.

Mike Holt even defines voltages for a tiny 500 amp surge on a 14 AWG wire:
> 6 inches  460 V; 20 inches 582 V; 30 inches 782 V. ...

You can do the math.  That is not resistance.  That is impedance.

Denials come only from hearsay; not from basic electrical knowledge and not from informed professionals. Power outage does not damage hardware. Adjacent protectors do not provide effective protection.  Effective protection always means a potentially destructive transient is not inside a building.  Then robust protection inside all equipment is not overwhelmed.