Re: What are you using to protect your studio audio equipment from power issues?

Soundhaspriority wrote:
"bud--" <remove.budnews@xxxxxxx> wrote in message news:2bc57$4a82eb86$cde8d570$21213@xxxxxxxxxxxxxxxx
westom wrote:
On Aug 11, 12:17 pm, "Soundhaspriority" <nowh...@xxxxxxxxxxx> wrote:
Perimeter protection is best, and it starts with the design of the building.
Modern communications building are built from the ground up to implement the
practical equivalent of a Faraday Cage, in which no voltage potential can
exist. Unfortunately, none of us have the resources to implement what is
done in a multimillion dollar data center.
The best information I have seen on surges and surge protection for more 'ordinary' buildings is in a guide from the IEEE at:
<http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf>
And also guide from the NIST:
<http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf>

The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the unwashed masses.

Either we earth a 'whole house' protector.
Service panel suppressors are a real good idea.
But from the NIST guide:
"Q - Will a surge protector installed at the service entrance be sufficient for the whole house?
A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

Service panel suppressors do not prevent high voltages from developing between power and signal wires. To limit that voltage you need a *short* wire connecting the cable/phone entrance protectors to the ground at the power service. A ground wire that is too long is illustrated in the IEEE guide starting pdf page 40.

What does a protector do? Connect a surge to earth.
Nothing more. What did those plug-in protectors do?
The IEEE guide explains plug-in suppressors work by CLAMPING (limiting) the voltage on all wires (signal and power) to the common ground at the suppressor. The voltage between wires going to the protected equipment is safe for the protected equipment. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40).

The NIST guide, using US insurance information, suggests that most equipment damage is from high voltage between power and phone/cable wires. The example above shows how that high voltage can develop and be protected against.

Earthed the
surge destructively through the network of powered off computers.
Only if installed by incompetents that can't understand installation instructions.

All interconnected equipment needs to be connected to the same plug-in suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. These multiport suppressors are described in both guides.

A
protector is only as effective as its earth ground.
Everyone is in favor of system earthing.
According to the IEEE guide plug-in suppressors work primarily by clamping, not earthing.

How to make a protector even better? Upgrade the earthing.
Francois Martzloff, who was the NIST guru on surges, has written "the impedance of the grounding system to `true earth' is far less important than the integrity of the bonding of the various parts of the grounding system." That means a short ground wire from phone and cable entry protectors to the ground at the power service. After that you might consider earthing upgrades.

Will a plug-in protector stop or absorb surges? Stop and absorb is
what a plug-in protector must do.
For those with minimal reading and thinking ability the IEEE guide explains that plug-in suppressors work primarily by clamping. They do not work by "stopping" or "absorbing".

NIST says so bluntly
What does the NIST guide really say about plug-in suppressors?
They are "the easiest solution".
And "one effective solution is to have the consumer install" a multiport plug-in suppressor.

Contrary to w's beliefs, both the IEEE and NIST guides say plug-in suppressors are effective. The only 2 examples of protection in the IEEE guide use plug-in suppressors.

The type of UPS usually used has no intrinsic surge protection. The same protection as in plug-in suppressors is commonly added. High ratings are much easier to find in plug-in suppressors. Any surge protector in the US should be listed under UL1449.

According to the IEEE guide, "the vast majority (>90%) of both hard-wired and plug-in protectors use MOVs [metal oxide varistors] to perform the voltage-limiting function. In most AC protectors, they are the only significant voltage limiters."

As Scott wrote, at about 6000V there will be arc-over from service bussbars to the enclosure. After the arc is established the voltage will be hundreds of volts. Since the enclosure is connected to equipment-grounds/neutral/earthing-electrode (US) this dumps most energy from a large surge on power wires to earth.

Francois Martzloffs has written "The fact of the matter is that nowadays, most electronic appliances have an inherent immunity level of at least 600 V to 800 V". He suggests that the common 330V clamp level is more marketing than engineering, and better overall protection may use a higher clamp level. (Suppressors wouldn't clamp surges that are not a threat.)

What the OP should use depends on what he is trying to protect against.

--
bud--

Bud, I like your summary. It is a complex problem. The statements made by others that anything is absolutely true, or absolutely false, are themselves incorrect. I do note, however, that the IEEE guide falsely implies that all suppressors work by clamping. 99% is no all. This is true of Transzorb based protectors, but not series/avanlanche diode protectors. These bleed the surge off to ground so slowly that no significant rise in ground potential occurs -- due to the suppressor. Of course, other factors, such as induced currents and conditions elsewhere in the structure, can allow this to occur, but, at least, the inevitability of it is removed by using a series type suppressor.

The IEEE (and NIST) guide cover how the vast majority of suppressors (service and plug-in) work. Transzorbs, as you are probably well aware, have substantially the same effect as MOVs. Transzorbs limit the voltage better. MOVs have a very high current rating in a small package, which is why they are widely used.

I have not seen reliable information (i.e. other than from manufacturers) on series suppressors like you are describing. They are not, for example, in the IEEE "Emerald" book (on protecting sensitive electronics) that I have.

The statement that all protected equipment must be plugged into the same suppressor reflects an ideal that frequently cannot be achieved in practice. In my office, I have four separate UPS units, all plugged into a single dedicated 30 amp line, and have an eyewitness account of how this caused an equipment failure. The equipment is interconnected by gigabit ethernet. I had lost one router three months earlier, due to unknown cause, but this time, I was a witness.

It is an inherent risk of using plug-in suppressors where all wiring to a set of protected equipment does not go through the suppressor. Both of the examples in the IEEE guide, which use plug-in suppressors, carefully show how to route all wiring through the suppressor (that is, how to correctly use them for "multiple-link" equipment). Ethernet has a pretty high surge immunity level. Another option would be wireless or optical ethernet.

If there is a power service suppressor, and the phone entrance protector connects with a short wire it covers most surge problems for equipment connected to phone and power. A cable entrance protector does not limit the voltage between center conductor and shield (which the IEEE guide says can reach 2000-4000V). Some service panel suppressors include ports to run phone and cable and probably dish through. That would cover the vast majority of surge hazards. If all wiring does not go through downstream UPSs it would be preferable that the UPSs have minimal or no shunt surge protection.

It was a clear day. Local power, PECO, had been having some trouble with their switchgear. The power went off and on in the space of a second. I was staring at the Netgear router when the lights started flashing in unision, an indicator of total failure.

The most problematic surges come from lightning. Second worst are from utility operations both normal (like switching power factor correction capacitors) and abnormal (like clearing faults).

--
bud--

The flaw in the hookup was that the Transzorbs and chokes in each of the UPSes had shaped a rather minor surge in different ways. This caused a voltage differential on the ethernet lines that blew it out. The differential could not have been caused by a spike on hot/neutral, because of the low capacitance of the switching supplies. And, of course, the computers themselves were undamaged. But the transzorbs lit up the ground. No other equipment in the house sustained any damage whatsoever.

A series type regulator reduces the risk of this kind of event.

Bob Morein
(310) 237-6511


.

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