DSL surge protector

[janclaes47]

On 4/4/2017 at 6:50 AM, westom said:

That FSPD-RJ11-Tele/4S numbers are all good for DSL with phone service. It would also be sufficient for a 'dry' DSL line (ie yours).  Only missing parameter is capacitance.  I would suspect it is low.  But they do not define capacitance and do not define protector technology.  So I can only suspect it is sufficient.

 

It says power levels will drop by less than 0.5 dB.  But is does not say at what frequencies that number applies - audio (phone) or DSL (radio).

 

Earth that on your DSL line.  Then view ADSL modem power levels on that modem's status pages.  If a protector has low capacitance, then dB power levels will remain unchanged.  You would be good to go.

 

Today I received the device pictured in post #24, and checked the SNR and Line attenuation before and after fitting the device.

 

The only difference I can notice is that the Downstream SNR has decreased from 10.3 to 9.6 dB, and the Downstream LA has increased by about 0.4 dB to 18dB.

 

The Upstream SNR seems to fluctuate a bit between 11 and 12 dB, but maybe that's normal, before attaching it stood at 12.3 dB.

 

I haven't connected the earthing line yet, so don't know if that influence the power levels.

 

Edit : connected the earth line, and figures stay as above.

 

 

 

Edited April 28, 2017 by janclaes47

[RichCor]

Your ADSL drop wire should have one of these over-voltage (surge) arrestors already attached to a ground-rod on the outside of your building.

[janclaes47]

23 minutes ago, RichCor said:

Your ADSL drop wire should have one of these over-voltage (surge) arrestors already attached to a ground-rod on the outside of your building.

Nothing like that in the whole of my installation.

 

My wire come in underground, then enters the house where all the electric wiring enters in the loft, and from there goes to the storage where the router is.

[RichCor]

These are usually provided and installed by the Thai Telco/Internet Provider (CAT/TOT), and simply consist of a plasma Gas Discharge Tube (GDT) with the center post connected on shortest possible path to an Earth Ground Rod.  

 

GDT circuit protection devices dissipate electrical 
surge energy safely within a contained plasma gas. 
Commonly used to help protect sensitive telecom and 
networking equipment and lines, GDTs protect from 
damage that may result from lightning strikes and 
equipment switching operations.

[Pib]

GDTs are indeed used but they are slower that MOVs (varistors) to respond to surges although they can handle a higher discharge current..   Higher quality surge protectors sometimes use both GDTs and MOVs, but most now days just use MOVs.

 

https://www.linkedin.com/pulse/comparison-contrast-between-gdt-mov-newman-liang

[RichCor]

 

2 hours ago, Pib said:

lity surge protectors sometimes use both GDTs and MOVs, but most now days just use MOVs.

 

Someone really needs to publish an idiot's Guide to Surge Protection as used to protect sensitive low-power data/control lines, and Mains Current plugged devices.  Whatever Surge Suppression/Protection technology is used, it should also be inspected/tested or replaced on a regular basis as their magical protection properties become exhausted or compromised.  Especially so if a lightning strike has hit nearby.

 

While MOVs can be used to shunt over-current to Ground, they also can absorb energy, and as Wikipedia: Surge Protector states:

 

Metal oxide varistor (MOV)

Cumulative degradation occurs as more surges happen. For historical reasons, many MOVs have been incorrectly specified allowing frequent swells to also degrade capacity. In this condition the varistor is not visibly damaged and outwardly appears functional (no catastrophic failure), but it no longer offers protection. Eventually, it proceeds into a shorted circuit condition as the energy discharges create a conductive channel through the oxides.

 

Gas discharge tube (GDT)

Like MOVs, GDTs have a finite life expectancy, and can handle a few very large transients or a greater number of smaller transients. The typical failure mode occurs when the triggering voltage rises so high that the device becomes ineffective, although lightning surges can occasionally cause a dead short.

[KhunHeineken]

 

I started a thread on this forum a long time ago about surge protectors in Thailand.

 

The theme to that thread was that surge protectors will not work as they should in Thailand because of the 2 pin plugs and no third pin to earth. 

 

This is the one I bought.  Not cheap.

 

http://www.belkin.com/au/p/P-F5C791-C6/

 

I still use it because I already bought it before starting that thread, but was told on this forum that it will not work if the property is not grounded to earth, which most properties in Thailand are not. 

Edited April 29, 2017 by KhunHeineken