CAN bus lightning protection

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CAN bus lightning protection

James Cameron-2
G'day,

I'm looking for suggestions to give to my electrician to fix a
potential vulnerability in my home power system.

Home is on a farm about 12 km from substation in town.  A 22 kV
two-wire feeder transmission line goes to several other farms, and one
branch comes to a pole-mounted transformer which drops it to 240 V.  A
local earth is established there.

After the transformer is about 198 metres of underground cable, which
comes up into our main panel.  Another local earth is established
there.

Text diagram;

substation --> transmission line --> transformer --> cable --> house

(A telephone copper pair also travels roughly the same route and enters
the house a few metres from the underground cable.  Trenches for both
cable are laterally separated by about three to five metres.)

At the house there are the usual domestic loads, a solar array with
microinverters, and a garage shed.  An underground conduit runs from
the house to the garage shed, about 30 metres.  The shed has a
subpanel, and does not have a local earth.  Shed and house are all
metal construction with concrete slabs.

Inside the garage shed are two backup battery assemblies each with
built-in inverter.  Each battery has a rated capacity of 13.5 kWh.

Main panel has next to it a subpanel with a contactor, and an embedded
computer with WiFi and 3G antennae.  The contactor separates the house
from the grid in order to power the house from the batteries.

A cable links the subpanel to the batteries.  The cable carries CAN
bus and 12V power.  It looks like Cat-5 cable.  It goes through the
underground conduit between the buildings.

Text diagram;

grid --> contactor --> loads <-- solar array <-- battery

Usually, when a grid outage occurs, the solar and battery inverters
cease generating, the contactor opens, and then the battery inverters
resume generating.  Frequency is then locally controlled.

During January, lightning struck nearby, with the thunder coming
within about one second from the direction of the transmission line
and pole transformer, and a grid outage began.  Drop-down fuses on the
22 kV side of the transformer did drop down.

Contrary to design intent, the contactor did not activate, and the
batteries did not resume generating.  All internet communication with
the battery system stopped.

Later analysis suggested destruction of the CAN bus transceivers in
both battery assemblies, and the subpanel.  When a technician tried to
bring up the subpanel embedded computer using a 12 V portable battery,
there was smoke and smell from the PCB.  When they tried the same with
the battery assemblies using a CAN bus USB adapter attached to a
laptop, there was no response.

Repairs of all three components are in progress.

No other appliances were damaged in the event.

At the time of the lightning strike, the batteries were fully charged,
and four air conditioners were on full tilt, so the battery inverters
were supplying power to the loads.  The ground and subsoil is dry,
after years of drought.

I'm looking for how to protect each of the components from similar
events.

It has been 25 years since I last read a text book on lightning
protection.

I don't have specifications of the existing lightning protection and
have been unable to get them.

--
James Cameron
http://quozl.netrek.org/
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
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Re: CAN bus lightning protection

Jason White-20
If all else fails, the company I work for makes CAN bus to fiber optic
modules. I recently worked on a customized version of the product which is
currently being used in the NASA X57 research aircraft (battery electric
drive).

On Monday, May 25, 2020, James Cameron <[hidden email]> wrote:

> G'day,
>
> I'm looking for suggestions to give to my electrician to fix a
> potential vulnerability in my home power system.
>
> Home is on a farm about 12 km from substation in town.  A 22 kV
> two-wire feeder transmission line goes to several other farms, and one
> branch comes to a pole-mounted transformer which drops it to 240 V.  A
> local earth is established there.
>
> After the transformer is about 198 metres of underground cable, which
> comes up into our main panel.  Another local earth is established
> there.
>
> Text diagram;
>
> substation --> transmission line --> transformer --> cable --> house
>
> (A telephone copper pair also travels roughly the same route and enters
> the house a few metres from the underground cable.  Trenches for both
> cable are laterally separated by about three to five metres.)
>
> At the house there are the usual domestic loads, a solar array with
> microinverters, and a garage shed.  An underground conduit runs from
> the house to the garage shed, about 30 metres.  The shed has a
> subpanel, and does not have a local earth.  Shed and house are all
> metal construction with concrete slabs.
>
> Inside the garage shed are two backup battery assemblies each with
> built-in inverter.  Each battery has a rated capacity of 13.5 kWh.
>
> Main panel has next to it a subpanel with a contactor, and an embedded
> computer with WiFi and 3G antennae.  The contactor separates the house
> from the grid in order to power the house from the batteries.
>
> A cable links the subpanel to the batteries.  The cable carries CAN
> bus and 12V power.  It looks like Cat-5 cable.  It goes through the
> underground conduit between the buildings.
>
> Text diagram;
>
> grid --> contactor --> loads <-- solar array <-- battery
>
> Usually, when a grid outage occurs, the solar and battery inverters
> cease generating, the contactor opens, and then the battery inverters
> resume generating.  Frequency is then locally controlled.
>
> During January, lightning struck nearby, with the thunder coming
> within about one second from the direction of the transmission line
> and pole transformer, and a grid outage began.  Drop-down fuses on the
> 22 kV side of the transformer did drop down.
>
> Contrary to design intent, the contactor did not activate, and the
> batteries did not resume generating.  All internet communication with
> the battery system stopped.
>
> Later analysis suggested destruction of the CAN bus transceivers in
> both battery assemblies, and the subpanel.  When a technician tried to
> bring up the subpanel embedded computer using a 12 V portable battery,
> there was smoke and smell from the PCB.  When they tried the same with
> the battery assemblies using a CAN bus USB adapter attached to a
> laptop, there was no response.
>
> Repairs of all three components are in progress.
>
> No other appliances were damaged in the event.
>
> At the time of the lightning strike, the batteries were fully charged,
> and four air conditioners were on full tilt, so the battery inverters
> were supplying power to the loads.  The ground and subsoil is dry,
> after years of drought.
>
> I'm looking for how to protect each of the components from similar
> events.
>
> It has been 25 years since I last read a text book on lightning
> protection.
>
> I don't have specifications of the existing lightning protection and
> have been unable to get them.
>
> --
> James Cameron
> http://quozl.netrek.org/
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>


--
Jason White
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
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Re: CAN bus lightning protection

Alan Pearce
I would certainly look at using fiber between the buildings, running
data in a power conduit is never good, and especially in conditions
where the ground conditions are dry which has the potential to create
large offsets in the reference voltage between the two ends of the
cable.

A friend of mine had occasion to run a public address system in a
marque at a camp during high summer on very dry sandy soil, with an
audio feed going across the ground to the cookhouse, some 70-80 yards
away. Originally he used standard coax but got a lot of buzz in the
audio at both ends. He ended up running ordinary figure-8 cable which
acted as enough of a balanced line t the audio feed as far as induced
noise was concerned even thorough the transmitted audio was
unbalanced.

On Mon, 25 May 2020 at 11:26, Jason White
<[hidden email]> wrote:

>
> If all else fails, the company I work for makes CAN bus to fiber optic
> modules. I recently worked on a customized version of the product which is
> currently being used in the NASA X57 research aircraft (battery electric
> drive).
>
> On Monday, May 25, 2020, James Cameron <[hidden email]> wrote:
>
> > G'day,
> >
> > I'm looking for suggestions to give to my electrician to fix a
> > potential vulnerability in my home power system.
> >
> > Home is on a farm about 12 km from substation in town.  A 22 kV
> > two-wire feeder transmission line goes to several other farms, and one
> > branch comes to a pole-mounted transformer which drops it to 240 V.  A
> > local earth is established there.
> >
> > After the transformer is about 198 metres of underground cable, which
> > comes up into our main panel.  Another local earth is established
> > there.
> >
> > Text diagram;
> >
> > substation --> transmission line --> transformer --> cable --> house
> >
> > (A telephone copper pair also travels roughly the same route and enters
> > the house a few metres from the underground cable.  Trenches for both
> > cable are laterally separated by about three to five metres.)
> >
> > At the house there are the usual domestic loads, a solar array with
> > microinverters, and a garage shed.  An underground conduit runs from
> > the house to the garage shed, about 30 metres.  The shed has a
> > subpanel, and does not have a local earth.  Shed and house are all
> > metal construction with concrete slabs.
> >
> > Inside the garage shed are two backup battery assemblies each with
> > built-in inverter.  Each battery has a rated capacity of 13.5 kWh.
> >
> > Main panel has next to it a subpanel with a contactor, and an embedded
> > computer with WiFi and 3G antennae.  The contactor separates the house
> > from the grid in order to power the house from the batteries.
> >
> > A cable links the subpanel to the batteries.  The cable carries CAN
> > bus and 12V power.  It looks like Cat-5 cable.  It goes through the
> > underground conduit between the buildings.
> >
> > Text diagram;
> >
> > grid --> contactor --> loads <-- solar array <-- battery
> >
> > Usually, when a grid outage occurs, the solar and battery inverters
> > cease generating, the contactor opens, and then the battery inverters
> > resume generating.  Frequency is then locally controlled.
> >
> > During January, lightning struck nearby, with the thunder coming
> > within about one second from the direction of the transmission line
> > and pole transformer, and a grid outage began.  Drop-down fuses on the
> > 22 kV side of the transformer did drop down.
> >
> > Contrary to design intent, the contactor did not activate, and the
> > batteries did not resume generating.  All internet communication with
> > the battery system stopped.
> >
> > Later analysis suggested destruction of the CAN bus transceivers in
> > both battery assemblies, and the subpanel.  When a technician tried to
> > bring up the subpanel embedded computer using a 12 V portable battery,
> > there was smoke and smell from the PCB.  When they tried the same with
> > the battery assemblies using a CAN bus USB adapter attached to a
> > laptop, there was no response.
> >
> > Repairs of all three components are in progress.
> >
> > No other appliances were damaged in the event.
> >
> > At the time of the lightning strike, the batteries were fully charged,
> > and four air conditioners were on full tilt, so the battery inverters
> > were supplying power to the loads.  The ground and subsoil is dry,
> > after years of drought.
> >
> > I'm looking for how to protect each of the components from similar
> > events.
> >
> > It has been 25 years since I last read a text book on lightning
> > protection.
> >
> > I don't have specifications of the existing lightning protection and
> > have been unable to get them.
> >
> > --
> > James Cameron
> > http://quozl.netrek.org/
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
> >
>
>
> --
> Jason White
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist