Hi Alex,
You provide little information about the equipment, the circuit that the varistor is protecting and your reason for wanting to remove it.
The varistor is likely to be protecting against high voltage surges and transientsbetween Live-Neutral, Live-Earth, Neutral-Earth, Signal/Comms
All
Why are telecommunications port emissions so much higher than AC power ports?
Regards
Andy
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Hi Tony,
The original design authority put it there for good reason and it should not
be removed without understanding why it is there. Varistors are usually not
superfluous in their application.
You're absolutely right. This varistor was populated for the surge protection.
Why do you want
In message 1403257835.918718...@m.mail.ru, dated Fri, 20 Jun 2014,
Alexey Musin amu...@inbox.ru writes:
One thing I keep in mind in all of it.
The varistor can leak, and the leakage current
may be dangerous for the end users.
So I have a lot of doubts about safety of this circuitry.
Which
Hi, John!
So I have a lot of doubts about safety of this circuitry.
Which standard applies to the product? Some standards require a gas
discharge tube (GDT) in series with the MOV so that there is no leakage
current.
It's a mains power filter. It has a number of modules.
One of these
Which standard applies to the product? Some standards require a gas
discharge tube (GDT) in series with the MOV so that there is no leakage
current.
John, your info about that requirement is very useful. I did not know it.
Could you tell what standards do contain the 'GDT+MOV' requirement?
In message 1403262722.268906...@m.mail.ru, dated Fri, 20 Jun 2014,
Alexey Musin amu...@inbox.ru writes:
It's a mains power filter. It has a number of modules. One of these
modules is an SPD (surge protection device). We've got a national
standard, which is very similar to IEC 61643-1. I'm
In message 1403263446.946685...@m.mail.ru, dated Fri, 20 Jun 2014,
Alexey Musin amu...@inbox.ru writes:
Which standard applies to the product? Some standards require a gas
discharge tube (GDT) in series with the MOV so that there is no leakage
current.
John, your info about that requirement
Andy,
Because to my knowledge, telecommunications ports have never caused any
interference ;-)
I'm sure someone else has a better answer.
Larry K. Stillings
Compliance Worldwide, Inc.
Test Locally, Sell Globally and Launch Your Products Around the World!
FCC - Wireless - Telecom - CE
John,
IEC 60950-1 and IEC 62368. However, there is a problem. Both of these
standards are not in a stable condition, so I'm not sure which version,
edition or amendment to direct you to, and I don't have time at present
to do a search. But there are people on this list who are much more
Hi Andy:
I don't know the answer to your question, but it may be due to the fact
that the distribution networks are quite different for telecom than for
AC mains. While an AC mains outlet may be interconnected with
several other residences nearby, a wireline telecom connection typically
goes
Hi Alex:
You can't pass the dielectric withstand test with
the varistor in place.
On the other hand, with the varistor in place, the
insulations supposedly won't see the transient
overvoltages, so there is no need to test whether or
not the insulations will withstand the transient
Hi.
I'm doing some research and am looking for recommendations for fume hoods
for abnormal condition testing for my lab. I have an opportunity to have
an exhaust to outside air system and am looking for your thoughts on what
has worked well for you in terms of cfm capacity and which
Peter,
Other than looking for an approved device, look for recommended CFM ratings
for the removal rates. Most home improvement stores have info on this. I
purchased a squirrel cage fan which removed air quickly and is much quieter
than a standard impeller type. My preference would be exhaust
Hi Peter:
Since you will be doing flammability tests, see
5.1 of UL94 which has specifications for the fume
hood. Note that during the flammability test,
the hood is draft free while permitting normal
thermal circulation of air past the specimen.
Best regards,
Rich
-
My current hood is stainless steel, with a large bubble in the exhaust tube
just above the hood. The bubble has fans fore and aft. The bottom lip of the
hood is used to hang Lexan 'shields' on three sides; this is because I wanted
them removable so that I can also use the underlying bench as
My boss immediately said that below was a Freudian slip. Should have been You
would probably not get this additional functionality on the stuff intended for
chem or bio labs.
Brian
-Original Message-
From: Brian Oconnell [mailto:oconne...@tamuracorp.com]
Sent: Friday, June 20, 2014
Hello Andy-
(Your question seems appropriate for a Friday, asked after the boss and
most everyone else has left for the weekend and you're sitting at the
workbench with eyes to the ceiling and palms up, waiting for the
answer...)
I think Joe has part of the answer, in that the impedance
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