> On 13/04/2021 10:49 am, Joe Gwinn wrote:
>> On Mon, 12 Apr 2021 17:59:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
>> wrote:
>>
>>> On Sunday, April 11, 2021 at 8:53:28 PM UTC-7, Steve Wilson wrote:
>>>> whit3rd <whi...@gmail.com> wrote:
>>>>
>>>>> On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
>>>>>
>>>>>> I have never heard of or seen spark gaps in, or added to, panelboards
>>>>>> here (US) other than what appears to be an intentional design to
>>>>>> arc-over.
>>>>>
>>>>> In dry-land parts of this state, a sacrificial spark plug is often
>>>>> added to electric service entrance... but rarely shown to building
>>>>> inspectors.
>>>> What kind of event is the plug intended to fix?
>>>
>>> Basically, dry ground has poor conduction for a ground rod, so
>>> it's for the kind of lightning event that induces currents on long
>>> lines.
>>>>
>>>> What happens if the plug arcs over? Wouldn't the surge current
>>>> available
>>>> destroy the plug and perhaps start a fire?
>>>
>>> Yep. If there's too many joules, that can happen anyhow. Plugs are
>>> cheap.
>>>>
>>>> Don't automotive spark plugs have a resistor embedded to reduce RFI? I
>>>> presume a non-resistor plug would be needed.
>>>
>>> Yes. This is an ancient folk remedy, might pre-date even the
>>> earliest solid-state arrestors of silicon carbide.
>>
>> Telephone land lines have had spark-gap surge arrestors for as long as
>> I can recall, probably dating back to Alexander Graham Bell.
>>
>> Joe Gwinn
>>
>
> Most likely it was Bell's idea. ;-) I worked on some land lines 60
> years ago and
> they were all over the place.
>
>
Before telephone lines there were telegraph lines and the Carrington event.
piglet
Reply by gray_wolf●April 14, 20212021-04-14
On 13/04/2021 10:49 am, Joe Gwinn wrote:
> On Mon, 12 Apr 2021 17:59:00 -0700 (PDT), whit3rd <whit3rd@gmail.com>
> wrote:
>
>> On Sunday, April 11, 2021 at 8:53:28 PM UTC-7, Steve Wilson wrote:
>>> whit3rd <whi...@gmail.com> wrote:
>>>
>>>> On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
>>>>
>>>>> I have never heard of or seen spark gaps in, or added to, panelboards
>>>>> here (US) other than what appears to be an intentional design to
>>>>> arc-over.
>>>>
>>>> In dry-land parts of this state, a sacrificial spark plug is often
>>>> added to electric service entrance... but rarely shown to building
>>>> inspectors.
>>> What kind of event is the plug intended to fix?
>>
>> Basically, dry ground has poor conduction for a ground rod, so
>> it's for the kind of lightning event that induces currents on long lines.
>>>
>>> What happens if the plug arcs over? Wouldn't the surge current available
>>> destroy the plug and perhaps start a fire?
>>
>> Yep. If there's too many joules, that can happen anyhow. Plugs are cheap.
>>>
>>> Don't automotive spark plugs have a resistor embedded to reduce RFI? I
>>> presume a non-resistor plug would be needed.
>>
>> Yes. This is an ancient folk remedy, might pre-date even the
>> earliest solid-state arrestors of silicon carbide.
>
> Telephone land lines have had spark-gap surge arrestors for as long as
> I can recall, probably dating back to Alexander Graham Bell.
>
> Joe Gwinn
>
Most likely it was Bell's idea. ;-) I worked on some land lines 60 years ago and
they were all over the place.
>On Sunday, April 11, 2021 at 8:53:28 PM UTC-7, Steve Wilson wrote:
>> whit3rd <whi...@gmail.com> wrote:
>>
>> > On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
>> >
>> >> I have never heard of or seen spark gaps in, or added to, panelboards
>> >> here (US) other than what appears to be an intentional design to
>> >> arc-over.
>> >
>> > In dry-land parts of this state, a sacrificial spark plug is often
>> > added to electric service entrance... but rarely shown to building
>> > inspectors.
>> What kind of event is the plug intended to fix?
>
>Basically, dry ground has poor conduction for a ground rod, so
>it's for the kind of lightning event that induces currents on long lines.
>>
>> What happens if the plug arcs over? Wouldn't the surge current available
>> destroy the plug and perhaps start a fire?
>
>Yep. If there's too many joules, that can happen anyhow. Plugs are cheap.
>>
>> Don't automotive spark plugs have a resistor embedded to reduce RFI? I
>> presume a non-resistor plug would be needed.
>
>Yes. This is an ancient folk remedy, might pre-date even the
>earliest solid-state arrestors of silicon carbide.
Telephone land lines have had spark-gap surge arrestors for as long as
I can recall, probably dating back to Alexander Graham Bell.
Joe Gwinn
Reply by Steve Wilson●April 12, 20212021-04-12
whit3rd <whit3rd@gmail.com> wrote:
> On Sunday, April 11, 2021 at 8:53:28 PM UTC-7, Steve Wilson wrote:
>> whit3rd <whi...@gmail.com> wrote:
>>
>> > On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
>> >
>> >> I have never heard of or seen spark gaps in, or added to, panelboards
>> >> here (US) other than what appears to be an intentional design to
>> >> arc-over.
>> >
>> > In dry-land parts of this state, a sacrificial spark plug is often
>> > added to electric service entrance... but rarely shown to building
>> > inspectors.
>> What kind of event is the plug intended to fix?
>
> Basically, dry ground has poor conduction for a ground rod, so
> it's for the kind of lightning event that induces currents on long lines.
>>
>> What happens if the plug arcs over? Wouldn't the surge current available
>> destroy the plug and perhaps start a fire?
>
> Yep. If there's too many joules, that can happen anyhow. Plugs are
cheap.
>>
>> Don't automotive spark plugs have a resistor embedded to reduce RFI? I
>> presume a non-resistor plug would be needed.
>
> Yes. This is an ancient folk remedy, might pre-date even the
> earliest solid-state arrestors of silicon carbide.
Good info. Thanks
--
The best designs occur in the theta state. - sw
Reply by whit3rd●April 12, 20212021-04-12
On Sunday, April 11, 2021 at 8:53:28 PM UTC-7, Steve Wilson wrote:
> whit3rd <whi...@gmail.com> wrote:
>
> > On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
> >
> >> I have never heard of or seen spark gaps in, or added to, panelboards
> >> here (US) other than what appears to be an intentional design to
> >> arc-over.
> >
> > In dry-land parts of this state, a sacrificial spark plug is often
> > added to electric service entrance... but rarely shown to building
> > inspectors.
> What kind of event is the plug intended to fix?
Basically, dry ground has poor conduction for a ground rod, so
it's for the kind of lightning event that induces currents on long lines.
>
> What happens if the plug arcs over? Wouldn't the surge current available
> destroy the plug and perhaps start a fire?
Yep. If there's too many joules, that can happen anyhow. Plugs are cheap.
>
> Don't automotive spark plugs have a resistor embedded to reduce RFI? I
> presume a non-resistor plug would be needed.
Yes. This is an ancient folk remedy, might pre-date even the
earliest solid-state arrestors of silicon carbide.
Reply by Steve Wilson●April 12, 20212021-04-12
whit3rd <whit3rd@gmail.com> wrote:
> On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
>
>> I have never heard of or seen spark gaps in, or added to, panelboards
>> here (US) other than what appears to be an intentional design to
>> arc-over.
>
> In dry-land parts of this state, a sacrificial spark plug is often
> added to electric service entrance... but rarely shown to building
> inspectors.
What kind of event is the plug intended to fix?
What happens if the plug arcs over? Wouldn't the surge current available
destroy the plug and perhaps start a fire?
Don't automotive spark plugs have a resistor embedded to reduce RFI? I
presume a non-resistor plug would beneeded.
--
The best designs occur in the theta state. - sw
Reply by ●April 11, 20212021-04-11
On Sun, 11 Apr 2021 11:10:00 -0600, bud-- <null@void.com> wrote:
>On 4/10/2021 3:04 PM, upsidedown@downunder.com wrote:
>> On Sat, 10 Apr 2021 02:53:20 -0600, bud-- <null@void.com> wrote:
>>
>>>
>>> Francois Martzloff was the surge expert at the US-NIST. He investigated
>>> how much energy might be absorbed in a MOV in a plug in suppressor.
>>> Branch circuits were 10M and longer, and the surge on incoming power
>>> wires was up to 10,000A. (That is the maximum that has any reasonable
>>> probability of occurring and is based on a 100,000A strike to a utility
>>> pole adjacent to the house in typical urban overhead distribution. Only
>>> 5% of strikes are stronger.) The maximum energy at the MOV was a
>>> surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less.
>>>
>>> There are 2 reasons the energy is so small. One is that at about 6,000V
>>> there is arc-over from the service panel bussbars to the enclosure (this
>>> appears to be a 'feature' of US panels). After the arc is established
>>> the voltage is hundreds of volts. Since the enclosure/ground/neutral are
>>> connected to the earthing system (US) that dumps most of the incoming
>>> surge energy to earth.
>>
>> The professional method is to have proper spark gaps in the main
>> distribution panel with known turn-on voltages. Better yet, have the
>> spark gap outside the house.
>>
>> In countries with long mains lines, the customers at the end of the
>> line is in the worst situation, since over voltages are largest. Think
>> about an open transmission line, in which the forward wave is
>> reflected back from the "open" end of the transmission line,
>> increasing the voltage. Getting spark gaps at into the last pole of
>> the long line would be the best solution. You could try to get the
>> utility company to install such devices and even offer to pay for the
>> installation.
>>
>
>I have never heard of or seen spark gaps in, or added to, panelboards
>here (US) other than what appears to be an intentional design to
>arc-over. A short duration 10kA max surge is well within the
>capabilities of MOV based protection.
Most electric meters have spark gaps.
Here in California we rarely see lightning; it's a real novelty. The
power lines don't generally have the high ground wire like most places
have.
--
John Larkin Highland Technology, Inc
The best designs are necessarily accidental.
Reply by whit3rd●April 11, 20212021-04-11
On Sunday, April 11, 2021 at 9:12:25 AM UTC-7, bud-- wrote:
> I have never heard of or seen spark gaps in, or added to, panelboards
> here (US) other than what appears to be an intentional design to
> arc-over.
In dry-land parts of this state, a sacrificial spark plug is often
added to electric service entrance... but rarely shown to building
inspectors.
Reply by bitrex●April 11, 20212021-04-11
On 4/11/2021 12:37 PM, upsidedown@downunder.com wrote:
> On Sun, 11 Apr 2021 10:56:17 -0400, bitrex <user@example.net> wrote:
>
>> On 4/10/2021 5:04 PM, upsidedown@downunder.com wrote:
>>> On Sat, 10 Apr 2021 02:53:20 -0600, bud-- <null@void.com> wrote:
>>>
>>>>
>>>> Francois Martzloff was the surge expert at the US-NIST. He investigated
>>>> how much energy might be absorbed in a MOV in a plug in suppressor.
>>>> Branch circuits were 10M and longer, and the surge on incoming power
>>>> wires was up to 10,000A. (That is the maximum that has any reasonable
>>>> probability of occurring and is based on a 100,000A strike to a utility
>>>> pole adjacent to the house in typical urban overhead distribution. Only
>>>> 5% of strikes are stronger.) The maximum energy at the MOV was a
>>>> surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less.
>>>>
>>>> There are 2 reasons the energy is so small. One is that at about 6,000V
>>>> there is arc-over from the service panel bussbars to the enclosure (this
>>>> appears to be a 'feature' of US panels). After the arc is established
>>>> the voltage is hundreds of volts. Since the enclosure/ground/neutral are
>>>> connected to the earthing system (US) that dumps most of the incoming
>>>> surge energy to earth.
>>>
>>> The professional method is to have proper spark gaps in the main
>>> distribution panel with known turn-on voltages. Better yet, have the
>>> spark gap outside the house.
>>>
>>> In countries with long mains lines, the customers at the end of the
>>> line is in the worst situation, since over voltages are largest. Think
>>> about an open transmission line, in which the forward wave is
>>> reflected back from the "open" end of the transmission line,
>>> increasing the voltage. Getting spark gaps at into the last pole of
>>> the long line would be the best solution. You could try to get the
>>> utility company to install such devices and even offer to pay for the
>>> installation.
>>
>> Yes, over distances like a hundred miles the electrical length of the
>> line at 50-60Hz is enough to cause reflection-effects like with RF in an
>> unterminated cable and give a nice boost at the end, there's an analysis
>> in e.g.:
>>
>> <https://www.worldcat.org/title/transmission-lines-and-networks/oclc/600926364>
>
> Lightnings are RF. Just listen with a radio at LF/MF bands and even
> up to lower part of the HF band and you can hear crackle all over,
> especially in the summer.
>
> While the "standard" lightning current pulse is 8/20 us, some sources
> claim a 3 ,s rise time, i.e. 10 us cycle time or 100 kHz frequency.
> This translates to a 3 km wavelength.
Ya, the same math of course applies to "shorter" transmission lines with
higher equivalent frequencies
> In the 230/400 V world low voltage distribution lines can be longer
> than a kilometer, which is a significant part of the wavelength and
> transmission line issues must be observed. Since the power line RF
> impedance is a few hundred ohms and one or both ends of the
> transmission line has an open circuit., the RF pulse will reflect a
> few times back and forth, until attenuated by resistive losses or
> flashovers.
>
I thinking about what happens if a surge is generated internal to the
utility from e.g. a switch-over or break in a long-distance high voltage
transmission line; if those are always arrested at a substation prior to
being coupled into low voltage distribution or if they can propagate
down to the user. Those lines must be very dispersive at high frequency
over tens of miles so the RF from a lightning strike or transient of a
cut-out would disperse over that distance I would think but there's
still the possibility of transmission line effects from the low
frequency/dispersed transient over that distance
Reply by ●April 11, 20212021-04-11
On Sun, 11 Apr 2021 11:10:00 -0600, bud-- <null@void.com> wrote:
>On 4/10/2021 3:04 PM, upsidedown@downunder.com wrote:
>> On Sat, 10 Apr 2021 02:53:20 -0600, bud-- <null@void.com> wrote:
>>
>>>
>>> Francois Martzloff was the surge expert at the US-NIST. He investigated
>>> how much energy might be absorbed in a MOV in a plug in suppressor.
>>> Branch circuits were 10M and longer, and the surge on incoming power
>>> wires was up to 10,000A. (That is the maximum that has any reasonable
>>> probability of occurring and is based on a 100,000A strike to a utility
>>> pole adjacent to the house in typical urban overhead distribution. Only
>>> 5% of strikes are stronger.) The maximum energy at the MOV was a
>>> surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less.
>>>
>>> There are 2 reasons the energy is so small. One is that at about 6,000V
>>> there is arc-over from the service panel bussbars to the enclosure (this
>>> appears to be a 'feature' of US panels). After the arc is established
>>> the voltage is hundreds of volts. Since the enclosure/ground/neutral are
>>> connected to the earthing system (US) that dumps most of the incoming
>>> surge energy to earth.
>>
>> The professional method is to have proper spark gaps in the main
>> distribution panel with known turn-on voltages. Better yet, have the
>> spark gap outside the house.
>>
>> In countries with long mains lines, the customers at the end of the
>> line is in the worst situation, since over voltages are largest. Think
>> about an open transmission line, in which the forward wave is
>> reflected back from the "open" end of the transmission line,
>> increasing the voltage. Getting spark gaps at into the last pole of
>> the long line would be the best solution. You could try to get the
>> utility company to install such devices and even offer to pay for the
>> installation.
>>
>
>I have never heard of or seen spark gaps in, or added to, panelboards
>here (US) other than what appears to be an intentional design to
>arc-over. A short duration 10kA max surge is well within the
>capabilities of MOV based protection.
>
>Also don't know of spark gaps in bigger commercial/industrial service
>switchgear.I have seen MOV based protection. The max surge should still
>be something like 10kA (less because of 4 wire 3-phase, more because
>transformers only supply one building).
For instance Phoenix Contact used to make spark gaps for 230/400 V and
400/690 V. They had blow holes to exit the hot plasma, so mot nice in
an EXplosive environment :-).
While we visually see a single lightning, it usually consists of
multiple bolts within half a second. The surge protector of any type
must be able to handle these multiple bolts without overheating.