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Giacomo
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I have a DS300 system with the Pro stop & go box and I use Parma Plus controllers. EDIT: single PSU
I would like to add fuse protection to the track but I am not 100% sure where to install them.
My best guess is to install them on the + wire between the track and the stop & go box one for each lane so I can have the correct sizing depending on the most demanding car and controller resistor. Or should I install it in the main power line but in this case the rating of the fuse have to be the sum of the max Amps of all cars.

Any comment will help me.
Thanks,
JamieG
 

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Giacomo
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Discussion Starter · #2 ·

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99% of power supplies already have circuit protection.

Rick
 

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Giacomo
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Discussion Starter · #4 ·
Rick,
I have a 30A 3-15.4V Rapid PSU.
I have already experience a resistor failure with a hot motor. I had 45Ohms resistors now I am down to 35Ohms and thinking to go down further to use safely some of the hottest motors
I have (mainly NSR with 25k rpm + one 30k rpm and they can drag easily up to 2-3A).

Cheers,
JamieG
 

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Rich Dumas
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If you have a large power supply its fuse or or other protective device will only safeguard the power supply. It is better to have a seperate fuse or breaker for each lane. I would put it in the plus side of the circuit. 2 amps might be a good value to use.
 

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Does not the amperage depend on what load you put on the track and the power supply to the track? If you have multiple cars on the track and LCs, then the amps can add up. I thought the max amperage on the PB-Pro+SH was something like 8 amps (if modified for 2 lane analogue) or higher???

So where would the fuse go on a digital track where both lanes are essentially one?

Anyway, would not a circuit breaker be better than a fuse or is the fuse just faster to respond?

Cheers!
 

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If the PSU senses a short it turns off so nothing on the track can be damaged. Its essentially a fuse.
Not sure why you need resistor on motor?
If you wish to add an additional fuse the place to put it is between rails and PSU.

Rick
 

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Hi JamieG
Your power supply will have circuit protection to stop it going over 30 amps.
I doubt you are running the sorts of cars that need anywhere near that.
As Rich says, it is better to have a seperate fuse or breaker for each lane.
The fuse needs to take motor's maximum current, 2 amps is OK for standard home set type cars, you may well need a higher rating for hotter motors.

You say you have had resistor failure (presumably that's your controller resistor) , resistor failure is usually due to overheating at part power - less than the motor's maximum current.
The fuse needs to take motor's maximum current.
So a fuse will do nothing to protect against this sort of resistor failure.

If all the action happens near the full power band on a hot motor, a lower value resistor will help because it spreads the heat over more turns of resistance wire. It'll probably make the car easier to drive too.

Double barrel resistors get rid of heat better
Adding a cooling fan, or a heatsink will help too.

(Running a lower current motor, or turning the voltage down, will reduce resistor heating. I guess those aren't what you want to do.
Driving the car on full power for more of the time will also reduce resistor heating. I guess you are already driving it as fast as it will go.)
 

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Giacomo
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Discussion Starter · #9 ·
Slotracing Al,
I have Parma Plus controllers, so there is a heatsink. The failure happen with hotter motor as you say near the the full power band. With my old track I tried to have as long as possible straights to have full power but it contains quite few twisted sections so the heat in the controller resistor is there.
With the new 3 lane track in MDF I should have a better flow since the straights are little longer than before and there are no more R1 curves.
Does anyone know if I can install a double barrel resistor on a Parma Plus controller and what Ohms do you recommend (I have now 35Ohms controller resistors running between 11 and 12V i.e. with NSR motors 21 500rpm - 30 000rpm and Slot.it 22 000rpm - 25 000rpm beside conventional Mabuchi motors)?

Going back to the initial question: I understand the best way is to install the fuses between the PSU and and the box (I have a single PSU with separate feeders to the controller DS box) if I follow the readings in Chris Frost holy bible and the previously posted diagram.

Cheers,
JamieG

PS: I should be able to use my Truspeed PWM shortly so in that case I can try the Parma 16D motor
but in that case the fuse must be ...little higher rating, I guess 5A.
 

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Hi JamieG
A PWM controller should solve controller overheating problems

Overheating resistors normally fail near the full power band.
Failed resistors can be repaired - see Chris Frost's web site for instructions on how

If you want to invest in the resistance controller a double barrel Parma "Turbo resistor" would stand up to the heat better.
They will work with any Parma controller, although the plus chassis needs a little work where it curves round over the top of the resistor to make them fit.

I'll leave it to somebody who regularly runs that sort of spec cars to answer how many ohms you need. The right number of ohms for your needs will be the same for either normal or double barrel resistors.
 

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Giacomo
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Discussion Starter · #11 ·
I haven't notice it!!!
Thanks Al
<<<<
If overheated the most common failure is the wire burning out near the full power band. This can be repaired by unwinding one turn and soldering the end on, or by replacing one turn with another piece of resistance wire.

The resistance usually consists of a coil of resistance wire wound on a ceramic core. This is usually NiChrome wire - a nickel chromium alloy that had good resistance properties, is quite hard and will stand very high temperatures. Unfortunately NiChrome is not easy to solder. Satisfactory joints can be made by abrading the wire with fine emery paper, tinning immediately with an aggressive flux, then twisting the tinned wires together and flowing some more solder on the tinned wires.

An alternative resistance wire is constantan - a copper nickel alloy with very good resistance properties (in particular its resistance changes very little with temperature). This is softer than NiChrome and much easier to solder.
>>>>

Actually I have reparied the one with normal soldering but it fail quite quickly. Now I know how to do it, very good tip.

At the end of the article there is also a very useful guideline about Ohms.
<<<<
Basic home set 1/32 45 to 75 ohms Quicker home set type cars 15 to 45 ohms hard tyre cars with metal chassis 5 -15 ohms, Sponge tyre cars 2- 5 ohms.
>>>>

Cheers,
JamieG
 
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