modern transformers

John, could you please provide just some general info on the type of modern transformer and the time period for what you consider modern?   Are you looking at something like the MTH Z-500 through Z-1000? A K-Line Powerchief? Lionel CW80? Or a Lionel powerhouse?

@bluesman posted:

I currently run my layout with a post war lionel zw transformers.  I have circuit breakers between the transformer and the track.  

am I correct that the new transformers do not need any extra circuit breakers?  Thanks

I would generally call this a questionable conclusion IMO. Flat out, just because an electronic controlled transformer can sense current and can trip in in overload- most allow the overload for several seconds (example 5 or more) BEFORE tripping in order to not trip on momentary real load surges.

At the same time, many modern recent cars are coming with thinner and thinner pickup wiring. All it takes a derailment short and poof.

You add breakers and TVS to protect BOTH sides of this equation. Modern transformers can be damaged by inductive spikes and short circuit load currents. You specifically choose more advanced and controlled breakers and TVS diodes to protect to KNOWN STANDARDs of voltage and current trip points, as well as faster times to prevent expensive damage. Again, you pay a slight cost for buying the extra protection- but it's just that- an extra known protection layer you are specifying in hopes of protecting your expensive trains, transformers, and control systems. This cost is often near nothing when you look at your total investment in your layout and collection.

Just like buying insurance, you may look at it as a cost- something you cannot tangibly see the use of immediately. Flip that around to the day something goes wrong. What does one repair of your most expensive loco cost? What does having a Z4000 (now $500-$700) or ZW-L transformer ($1000) even CW80s have gone up!! Just replacing even ONE device in a failure or accident- how much did that breaker or TVS diode cost you?

Again, risk analysis is simple:

Rate of occurrence- typically high in this hobby- derailments shorts, accidents

Cost of even a single incident- again what is the minimum repair bill- again typically now day this can be a high dollar value

What is the maximum possible risk cost- example derailment kills MTH Premier loco PS3 board and at the same time kills a TIU channel or transformer channel

Cost of protection VS reduction in risk of damage? If breakers and TVS diodes cost you $40, but reduces the risk of even one occurrence.

Risk of doing nothing and rolling the dice- "I don't need protection"

It's your trains, your layout and your wallet.

Personally, when it comes to power sources and circuit protection, I nearly always take a "better safe than sorry" route.

You don't NEED extra circuit breakers between the MODERN TRANSFORMER and track BUT I would HIGHLY recommend a fast-acting fuse between your transformer and the track, and one or more TVS to protect from voltage spikes.(I'll stay away from TVS and voltage spikes for the rest of this posts so as not to give you an info overload)

Whether or not you want extra circuit breaker or fuse protection depends on the modern transformer you are using. Not all modern transformers' internal circuit breakers work properly consistently, nor do they protect against voltage spike.

I use 10amp inline auto fuses between my transformers and track. Here is how I power the track on 2 different blocks on my layout. For simplicity, in the first instance below I will NOT show the BPC I use on my layout but it will be included in the 2nd "flow diagram"?lol 

Key: "-->" - denotes the electrical flow from one component to the next

Track 1:

AC Ground: Two Lionel 135W Powerhouses*-->TPC400-->terminal board-->Track

AC Hot: 2 Lionel 135W Powerhouses**-->TPC400-->10amp fuse-->terminal board-->Track

Track 2:

AC Ground: Two 180W Powerhouses***-->Lionel 360w Legacy PM-->Terminal Board-->Track

AC Hot: 2 180W PHs-->360W Legacy PM-->10amp FUSE-->BPC-->FUSE-->Terminal Board--> Track

NOTES: -All fuses are 10amp, fast acting fuses(2 ATM, 1 ATC, 1 AGC)

*- The 135w Powerhouse has a 7.5amp circuit breaker

**- The wire connecting the Powerhouses to the TPC has an inline fuse for AC Hot)

***- The 180w PH has a 10amp, fast-acting circuit breaker

Before I mentioned not all modern transformers have reliable internal circuit breakers. For example, when a short occurs on the track powered by the180w powerhouses, the powerhouses will trip quicker than the external fuse. On the other hand, the 10amp fuse between the TPC400 and next component will blow BEFORE the 135w Powerhouses.

Thus, I only consider 4 or 5 modern transformers to be reliable and perform as told, those would be: The Newest Lionel ZW(I believe ZWL) , the Lionel GW180(a 180w PH connected to a CW80 like "controller"), the Lionel 180w Powerhouse, and maybe the new/revised CW80 and MTH4000- can't speak for much on the later 2 as I don't know much about them. I'd never run a modern loco without an external fuse between the transformer and track UNLESS the power source was the 180W Powerhouse.

In terms of newer transformers with internal circuit breakers that I believe need an external fuse or breaker between the transformer and track include: Lionel 135w PH, MTH Z-500, Z-750 and Z-1000, K-Line Powerchiefs(both versions), Lionel CW40, older Lionel CW80s, Lionel RS-1. Don't have enough info regarding the MRC 270w.

Hope that helps!

Fuses are cheap insurance. If you short out and blow a board you will find out the meaning of high dollar.

TVS diodes are a must too.

@bluesman posted:

I currently run my layout with a post war lionel zw transformers.  I have circuit breakers between the transformer and the track.  

am I correct that the new transformers do not need any extra circuit breakers?  Thanks

john,

It depends on how quickly those breakers trip.  If you've added fast ones, or the fuses as suggested by @feet and @StevefromPA, their fast tripping speed will ensure, to the greatest extent possible, that you will not harm any of your locomotives or powered rolling stock.  Also remember that the breakers or fuses handle excessive-current overloads.  There are also excessive-voltage overloads.  @Vernon Barry mentions the addition of TVS diodes to deal with over-voltage spikes.

Remember also that this arrangement, generally located between transformer and track, isn't perfect.  It would be much better to have a breaker (and TVS for that matter) inside the locomotive or car, close to what's being protected, but it may be hard and/or inconvenient to place the protection there, so we live with it outside.

Mike

To answer your question, to my knowledge the only newer transformers that give out of box total protection is the Lionel 180 brick or the ZWL transformer. I started with the brick/powerhouse combo and moved up to the ZWl. I’ve never lost any electronics from derails or crashes. I don’t use TVS’s or added breakers.

Depends how much money you can spend on repairs, for example a ps2 3 volt board the audio ic can short just from a track short derailment, generally not that expensive! but a ps 3 Diezel board which Costs $200.00 each with the same track short can be blown with one derailment track short and can sometimes be nonrepairable! An ounce of prevention is worth a pound of cure. highly recommended Tvs diodes before TIU and output of TIU to track! some asc tech's even install tvs diodes inside engine and also track terminal's around there layout! Alan