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Author Topic: Electrical installations: Spot five (hundred) errors..?  (Read 1681 times)

Hande

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Electrical installations: Spot five (hundred) errors..?
« on: March 08, 2016, 12:58:13 PM »

Please, look at my plan and come back with identification of errors  :D

The layout roughly represents the physical location of the components, although the location of the battery is dictated by ballast considerations.

There will be an "upstairs" electronics tray as, I have learned, is more or less state of the art.

Where are the sources of interference?
=> how should the corresponding components be installed rf. each other

How have you grounded your vessels?
I thought of putting in a proper ground wire around the bottom of the hull. That way ground would be available everywhere without a lengthy wire for that. All and any remaining lengthy wiring (exept the channel controls, of course) - which shall be minimised - would be "hot" and run "upstairs" as much as possible.


My build is: bit.ly/Neddie_of_Hande (in Mayhem)
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nemesis

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #1 on: March 08, 2016, 04:04:28 PM »

I have used a grounding plate bonded on the bottom of the hull. No need when you consider you can use the shaft outer instead. nemesis
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inertia

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #2 on: March 08, 2016, 04:50:01 PM »

As a schematic it looks fine. I don't really know why you want to run a ground cable all the way around the boat. All of the devices shown are designed for parallel cables + and -, so you would probably find that splitting them (i.e. running all the -ve wires to ground) would be a lot more like a rat's nest than sticking with convention. If you're intent on "earthing" the model then you could run just one cable from the P92 -ve to one of the prop shafts, as Nemesis says.
BTW don't forget that if you are using the BEC feed from P92 in conjunction with ESCs which also have BEC then you'll need to disable the Red Rx connection in both speed controllers.
As regards interference, the sensible things such as keeping the main power cables (battery to P92, P92 to ESCs, ESCs to motors) as short as possible and well away from the receiver aerial always apply. If you're using brushed motors and a 2G4 radio then you can get away without suppressor capacitors across the brushes, although I'd fit them anyway in case your motors might affect someone else's radio.
DM
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malcolmfrary

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #3 on: March 08, 2016, 05:42:58 PM »

Quote
Where are the sources of interference?
=> how should the corresponding components be installed rf. each other


How have you grounded your vessels?
I thought of putting in a proper ground wire around the bottom of the hull. That way ground would be available everywhere without a lengthy wire for that. All and any remaining lengthy wiring (exept the channel controls, of course) - which shall be minimised - would be "hot" and run "upstairs" as much as possible.
Interference usually originates with inductive components being switched.  Motors (brushes are a sort of switch and PWM ESCs work by rapid switching) and relays.  Both can create large back-emfs, these voltage spikes can either radiate as radio waves covering a wide spectrum (not as high as 2G4) or introduce odd voltages to the power lines.  Good quality suppressed motors cures one, properly designed circuits around relay coils sorts the other.  Motors that overpower their supply can also create voltage fluctuations that can look like interference.
I have never felt the need to ground - modern systems are designed to plug in in a star configuration, a dedicated ground line does not improve anything and has a very good chance of introducing problems by giving the potential for multiple paths in the ground line or ground connections where they are not wanted.  It is quite possible that it was thought a good idea back when many motors were not very good around radios, and there was a combination of desperation and wishful thinking. 
It is a different matter if a lot of items are fitted that are worked by switchers in the positive line - a solid common ground return makes sense then for the accessory wiring.
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Hande

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #4 on: March 08, 2016, 06:12:49 PM »

I'm grateful for your experienced remarks!

My urge about "grounding" is probably more than anything else a question about not ever seeing the cabling of a working model boat. The photos that I've seen are not very articulate about that.

I take that people don't usually seek earth from the propeller shaft tube? As an (over)engineer, I would like that in principle, but cannot think of a practical reasoning... :embarrassed:

Intertia's reference to convention is right, of course. As a newbie, I haven't seen conventions much. This is exactly why I am so glad about being sensible enough to join you smart  and experienced people!

I will drop the idea of a common -ve.
I will suppress the motors (which are 540, in fact) against interference - if they are not delivered with capacitors (they are on their way).
I am counting on my Graupner ESC's technology to be properly designed.

I like the engineering philosophy of Action Electronics, to be sure :D !!


Thank you again!!!  :-)

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Hande

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #5 on: March 09, 2016, 08:49:01 AM »




Thank you, Malcomfrary, for this. I will hang it on the wall of my man-cave. I do have some education on electricity and I understand your summary.  - Luckily, I had just read tutorial material about pulse-width modulation in R/C control :-)





Interference usually originates with inductive components being switched.  Motors (brushes are a sort of switch and PWM ESCs work by rapid switching) and relays.  Both can create large back-emfs, these voltage spikes can either radiate as radio waves covering a wide spectrum (not as high as 2G4) or introduce odd voltages to the power lines.  Good quality suppressed motors cures one, properly designed circuits around relay coils sorts the other.  Motors that overpower their supply can also create voltage fluctuations that can look like interference.
I have never felt the need to ground - modern systems are designed to plug in in a star configuration, a dedicated ground line does not improve anything and has a very good chance of introducing problems by giving the potential for multiple paths in the ground line or ground connections where they are not wanted.  It is quite possible that it was thought a good idea back when many motors were not very good around radios, and there was a combination of desperation and wishful thinking. 
It is a different matter if a lot of items are fitted that are worked by switchers in the positive line - a solid common ground return makes sense then for the accessory wiring.
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inertia

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #6 on: March 09, 2016, 10:59:10 AM »

Hande
This one's for you!
DM
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Hande

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Re: Electrical installations: Spot five (hundred) errors..?
« Reply #7 on: March 10, 2016, 08:04:42 AM »


Thank you, Dave! :} :} :} It's simply beautiful!
Like a diploma of sorts  ;D
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