On Sun, 21 Sep 2008 20:50:05 GMT
[email protected] wrote:
| Hi Phil
|
| Lets try and answer your questions.
|
| On 21-Sep-2008,
[email protected] wrote:
|
|> If *they* go ahead and change the surge protector designs so that the
|> clamping
|> voltage is doubled for the 120V protectors, then maybe that creates a
|> device
|> that could be used on twice the voltage.
|
| The answer is no, you could not use it at twice the voltage. Only the
| ratings of the MOVs between Live and Ground have been increased in voltage
| rating. The MOV between live and live is still the same (300VAC). If you
| tried to use the unit on a higher rated supply the MOV between live and live
| would fail, as it is only rated for a 240 VAC supply.
Your reference to "The MOV between live and live is still the same (300VAC)"
isn't making any sense here. If you are talking about a device intended for
120V as in USA, then there is no "live and live". There is only one live,
and a neutral, and a ground.
Unless you are referring to balanced power as in NEC 647. And that is quite
a different beast.
If the voltage of ALL the MOVs on a 120V power strip are doubled, then that
means the L-N are doubled, the L-G are doubled, and the N-G are doubled. So
then if I use that device on 240V (USA style) then we change L to L1, and N
to L2. So are yoy trying to say that when the voltage of a surge suppressor
is doubled, it's not really doubled on the L-N pairing (which becomes L1-L2
when used for 240V)?
|> If the clamping voltage in the USA is doubled, but this does not happen in
|> Europe, then the devices in both would end up being about the same, right?
|
| Yes the MOVs would be the same.
So why could the be used on 240V in Europe but not in USA?
|> I'm looking for devices to protect against surges at point of use for 240V
|> as wired in the USA. I could use a protective device from Europe, but it
|> would not be optimal. But my big point is, if they double the clamping
|> voltage of protective devices from USA, they would basically be the same
|> and this gives me another choice to find a device that should work be will
|> be less than optimal.
|
| If the device is a power strip the would it could have the same protection
| circuit, but it would not meet US or Canadian requirements due to the
| sockets been European and not meeting US or Canadian standards.
That's a different issue. I might swap out the receptacle parts, plus other
components that can only handle 120V.
|> So the remaining question is, if they do double the clamping voltage on
|> the
|> the models for the 120V market, are they usable on 240V? Would there be
|> any
|> difference between these "doubled for 120V" compared to the "normal for
|> 240V" models in UK (not considering the NEMA vs. BS outlets and plugs,
|> fusing requirements, etc).
|
| The answer should be yes if you ignore the differences in the standard
| requirements.
| Most counties other than the US base their standard on IEC 60884-1 for the
| electrical safety of the basic power strip and on IEC 61643-1 for surge
| suppression. So what is designed for Germany can also be sold in Holland,
| Spain etc. and what is designed for the UK can be sold in Hong Kong, Cyprus,
| Malta etc. Although Japan use the same socket as Japan it must be tested to
| Japanese standard and have a PSE approval before it can be sold there.
I have some "wall warts" that are rated for 100-240V 50/60Hz, but the plugs
are NEMA 1-15 (e.g. standard for 120V w/o ground pin).
|> Apparently some "experts" think that today's home appliances can withstand
|> some higher surge levels, and that the MOVs are being destroyed more often
|> than desirable in the protectors.
|
| They can, but they will last longer with the lower clampng voltage, It is
| the marketing department like to use the higher energy rating as a marketing
| tool, the engineer still prefer the lower clamping voltage.
But on 240V, the clamping voltage would be "just right" (doubled from 120V).
|> The only reason I see to have any more protection in the USA compared to
|> the UK
|> is that we have areas of the country with more frequent lightning.
|
| Not true some area of the UK have similar lighting strikes frequency as the
| US.
Some areas of the US have substantially more than most of the US. How does
the UK compare to say, Florida?
|> 1. So maybe we don't need a lower clamping voltage in the USA, given that
|> more and more appliances (especially computers) handle all of
|> 100-240V.
|
| As I have already said the lower the clamping voltage the longer the life of
| the protected device will be.
Of course. But I want to run the device at 240V for power efficiency.
|> 1+2+3 = more devices available (but I have to be very careful to choose
|> units
|> that have this doubled clamping voltage else the MOVs will give up their
|> magic
|> smoke as soon as I plug them in).
|
| NO any device rated for 240 VAC should give acceptable life both for your
| equipment and the protection device itself, if purchased from one of the
| major manufacturers. Do not be tempted to buy a cheap no name unit,
| irrespective of the manufacturers claims.
I never do that. I always want to know who to sue (even if that would be a
very unrealistic thing)