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DCC and electrostatic grass machines


Mike Mackay

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Hi all,

 

Is anyone aware of damage caused to DCC components by the use of electrostatic grass machines (near trackwork, obviously)?  I will shortly be at the stage of scenicing with one of these things and wonder whether any, or what, precautions are necessary.

 

I can switch out the booster, but circuit breakers for each power district are hard-wired to the busses.  Removing locomotives is a minor pain, but I shall probably do that. There are no auxiliary decoders on the layout.  Is there any value in jumping the busses to household ground temporarily?

 

Any comments or experience of this issue would be appreciated.

 

-- Mike

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All computers (and that's what your DCC controller and decoders are) are susceptible to damage by large electro-magnetic force (EMF) fields. Every electricsal device creates these fields including transformers and motors which run in close proximity to your controllers/decoders every day.

 

However large static charges can produce EMF spikes. Since you can't control the spark there is a small risk that you may cause damage to your DCC equipment when using a static applicator in close proximity. Only you can decide if you're willing to take that risk, personally I wouldn't.

 

Cheers

Dave

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  • RMweb Gold

Interesting topic.

My qualifications and experience tells me that it will have no effect as only one electrode is 'exposed' resulting in, in this case, 'floating' potentials.
(Don't touch the electrode inside the applicator!!!)

My brain asks “how much 'charge' is actually transferred when a 'handful' of grass lands into the glue?
(Where there is a path back to the static applicator.)

My heart says :–
“My trains, my trains! Don't let all that voltage anywhere near my precious trains!”


Kev.

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  • RMweb Gold

My brain asks “how much 'charge' is actually transferred when a 'handful' of grass lands into the glue?

 

At the recent excellent RMweb show, at the Ricoh, I was given a demonstration of a Static Grass Applicator.

 

The Vendor extolled the virtues of his design over others, and to be fair, it did work extremely well – especially when a certain member, with a stunning layout/thread here, also said he preferred this Applicator over other more 'expensive' offerings.

 

Anyways I digress, after finishing the demo, (I did not buy but will), a mother and daughter stepped up for the spiel. The Vendor immediately asked the girl, of about eight, if she would like a 'furry green' finger nail!

He did not, at this stage, emphasise the 18kV, (like he did with me!), but just said that she might feel “a little prickly sensation” and with that applied glue to the said nail, added grass to the applicator, switched it on and shook it, and then placed the 'free end' electrode on her finger near the nail and applied grass as if from a salt cellar.

 

Result – one rich even furry green finger nail and a very pleased little girl.

I was really impressed!

 

 

Now, how much voltage is “a little prickly sensation”?

I don't really know but some say they can 'feel' voltages above 12v.

But this is not really relevant.

The 'static' electricity(!), or charge, really really wants to get back to the Applicator.

It WILL take the easiest route too, and the electrode into the glue locally is this route.

The worst case would be to 'static grass' one rail whilst having the return electrode on the other. Would this 'kill' DCC stuff?

 

Again, I don't know but to ensure I never find out I will just follow Dutch_Master's advice and place a coin on the dead rails locally.

 

 

Kev.

:)

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Most people will feel quite low voltages on the tongue which is in a nice moist environment. DO NOT TRY THAT AT HOME.

 

Remember the old saying "It's the Amps that cramps and the Volts that jolts"

 

It may be 18KV, but it will be very low current and, as you correctly point out, what current there is will only be flowing through a few mm of nail and skin.

 

On the other hand a few 10s of volts can kill under the right (or should that be wrong) circumstances. Electrical equipment on UK building sites is (or used to be, I think the EU may have interfered) powered from 110 but this is sourced from a transformer with a centre tap connected to earth, so that no part of the equipment is ever more than  55V above earth potential.

 

It also depends on the individual. As I understand it, approximately 5% of the population will not be protected by a 30mA RCD in their home (way higher than what the static grass machine can source).

 

I wonder if the exhibition's health and safety rep was aware of what he was doing. No matter how safe it might be I can imagine the reaction these days :O

 

Andrew

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  • 6 months later...

To follow up on this issue, I recently asked the same question on the Railways of Germany forum, and Brian Gates posted a link to the following YouTube vid wherein a number of LEDs on the Miniatur Wunderland layout were apparently blown by the use of a static grass applicator.  I will be using suitable precautions when I have mine ready...

 

 

--  Mike

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