w_tom wrote:
Bud-- wrote:

...
Question:
If plug in surge suppressors are not effective, why does the paper,
divided into 7 sections, contain
section 5: Multi-port point-of-use (plug-in) protectors
section 6 Specific protection examples (all using SREs)
Place your answer in a separate post from other responses. I guess in
your excitement you forgot to explain this.



Every cited paper - and now we add Mike Holt to the list - does
not blindly recommend plug-in protectors. These papers discuss merits
(pluses and minuses) of such protection....

Major progress - IEEE (NIST, ...) now are recognized as recommending
plug-in surge protectors. There are, of course, pluses and minuses for
any protection scheme. Not obvious what other "cited paper" you refer to.

Figure 8 shows a plug-in protector adjacent to TV1. How much voltage
difference between that protector and earth? 8000 volts. Is that TV
going to charge up to 8000 volts and not find other, destructive paths
to earth? Of course not. 8000 volts can find paths - some
destructive - to earth via appliance. 8000 volts again demonstrates
why protection must be located at service entrance - why plug-in
protectors are not effective. Mike Holt makes a specific reference to
"properly used", and demonstrates why plug-in protectors can even
contribute to damage of adjacent electronics.


This paper is not Mike Holt's. It is from the IEEE. Mike only provides a
link to it. If Mike provided a link to the Bible, it would not become
Mike's document.

The IEEE provides this example to show how a SRE can protect the first
TV, and says that protection is effective. The IEEE paper says a second
SRE is needed at the second TV. If the CATV entrance is distant from the
power entrance, as this example describes, there can be a large
difference in the ground potential at the CATV ground block and the
power service ground, 10 kV as this example describes. A single point
ground reference at the power service for all incoming wires is
desirable but not always present.

In additon, the CATV ground block, as you have said, provides no surge
protection for the signal conductor - the limit being the flashover
voltage at connectors. IIRC the IEEE paper said this was about 4 kV,
which could appear at the TV antenna connection. The SRE has surge
protection on this wire, which is not provided in 'whole house'.


How curious? A point 1 in that Martzloff, et al paper says same
thing:


No link, or even name provided for paper. Hey, wasn't that a major issue
for larry moe 'n curly's reference to Consumer Reports??

Even personal experience by
tracing a surge through plug-in protector and then through powered off
and networked computers was cited. How many times need we cite but
another failure (damage) made easier by plug-in protectors?

The whole point of SREs is that they protect against this exact hazard.

AND where
does this mean Mike Holt recommends plug-in protectors? Bud - just
because Mike Holt discussed plug-in protectors does not - not for one
minute - mean that Section 5 *recommends* plug-in protectors.
Section 5 demonstrates numerous reasons why plug-in protectors can even
contribute to electronics damage. Mike Holt demonstrates difficulty in
making a plug-in protector effective.


You need to learn how to read. The IEEE (not Holt) provides section 5 to
show how SREs can provide protection, and follows with section 6 to
demonstrate specific examples of protecting with SREs. To say the IEEE
doesn't recommend SREs is remarkably dense.


Remember - they are shunt mode protectors. They shunt transients
to earth - to provide both conductivity and equipotential.

A MOV clamps the voltage across its terminals. Surge supressors
fundamentally clamp the voltages on the protected wires to a common
reference point. We both agree the ground path fom an receptacle to the
power service panel is relatively high resistance. The protection
provided by plug-in surge supressors is primarily by clamping, the
conduction to earth is secondary. In the fig 8/fig 9 TV example, most of
the earthing of the surge on the CATV service is via the "Coax sheath
ground bond" from the CATV entrance ground block to the power service
entrance (IIRC the paper says that).

How curious. The protector works by connection to earth ground. Why
does the plug-in protector manufacturer 1) not provide the dedicated
earthing connection, and 2) does not discuss earthing? Why does
plug-in manufacturer avoid discussing that 8000 volts? That's 8000
volts that will find other earthing paths within the room - except if
the room is constructed as part of the protection.


The plug-in protector works primarily by clamping. Essentially the whole
problem in this thread is that your religous views recognize only
earthing, not clamping. The IEEE recognizes SREs are effective, thus
action primarily by clamping can be effective.


BTW, Bud, everyone has a limited budget. $100 or $10,000 does many
times more at the 'whole house' as compared in plug-in protectors.
There is no separation between 'whole house' and plug-in solutions.
It all comes from the same dollar bills. More of one means less of
the other. Plug-in protectors typically cost tens of times more money
for inferior and complicated protection.

'Whole house' and single point ground are good ideas.

For power/phone/CATV/... entrances not immediately adjacent you won't
have single point ground. CATV ground blocks don't arrest surges
arriving on signal wire. Surges can arrive in other ways. Plug in surge
protectors can provide protection, as recognized by the IEEE (and others).


Show me every housewife who will address all those grounding
questions? Most men lurking here don't even fully understand the
concept.

Most men (and women) lurking here can read the IEEE paper and understand
it better than you.


Mike Holt describes another problem with plug-in protectors:

Typically, protector manufacturers cite a Joule rating
for the protector that is the sum of the (MOV
manufacturer's) Joule ratings for all the MOVs in the
product, and this has become a sort of "horsepower
race". However, especially in protectors of the 6C
design, the fusing may be set to such a low level that
the fuse opens (eliminating the surge protection) long
before the stated capability of the MOVs is reached.
If this happens, the claimed Joule rating is meaningless.


[The IEEE says Joule ratings are substantially meaningless.] Every
protection scheme is a series of tradeoffs. The circuit of 6B, with the
protected equipment downstream from the fuse, will disconnet the
protected equipment with the MOV. And the manufacturer may or may not
set the fusing to an appropriate level. The IEEE doesn't seem to see
this as a critical problem. Surge protectors installed at the electrical
service also have overcurrent protection which is subject to the same
problem.

================================================== ==============
Another relevant article is
http://www.ecmweb.com/mag/electric_o...ald/index.html
This is an article from "Electrical Construction and Maintenance"
magazine reviewing the book "IEEE Recommended Practice for Powering and
Grounding Sensitive Electronic Equipment" (the Emerald book in the color
book series)

A quoted definition from the IEEE Emeral book is:
"Surge reference equalizer. A surge-protective device used for
connecting equipment to external systems whereby all conductors
connected to the protected loads are routed, physically and
electrically, through a single enclosure with a shared reference point
between the input and output ports of each system."


With comment from the article:
"It has been found that, with multiport loads (such as computers with AC
power input and data communication ports, televisions with AC power and
CATV ports, or fax machines with AC power and telephone ports), a
transient voltage surge event on one port, even if protected by
transient voltage surge suppressor (TVSS), causes a transient voltage
surge to be impressed across the other ports, often causing damage to
the load equipment. One potential solution is the use of a surge
reference equalizer to prevent differences in the ports' ground
references under transient voltage surge conditions."

Fig 8 from the IEEE paper above is repeated in the book, and SREs are
recognized as a tool in protecting electronics - same as the IEEE paper
above.

bud--