Postwar transformers modern trains

Yes, you most certainly can, but there are some protections you'll want to add, namely fast-acting circuit breakers or fast-blow fuses and also transient voltage suppression (TVS) diodes are recommended, though not required.  That's a mouthful but it's actually pretty simple.

The circuit breaker inside the transformer only serves to protect the transformer itself, not the modern electronics in the engines on the tracks being powered by the transformer. In the event of a short (caused by, for example, a de-railment with wheels crossing the inner and an outer rail), the circuit breaker in the transformer isn't fast acting enough to protect your PWC engines electronics. You MIGHT fry them, especially if the derailment occurs where you're unable to reach or while your attention is away.

TVS diodes protect the electronics from unexpected voltage spikes.

So, while not needed, additional breakers or fast-blow fuses are highly recommended.

The additional breakers or fuses are connected on the hot wire between the transformer and track. The TVS diodes are connected across the transformer terminals or, as I do, across the lock-ons.

If you want to take advantage of the Train Master Command Control (TMCC) capabilities of your PWC engines, you'll need a Lionel Command Base and handheld remote control device. Without these, the PWC engines will still run in conventional mode, but you won't be able to access the full set of features like electro-couplers, speed variation, and the like.

Hope that helps get you started.

Required protections you'll want to add would be transient voltage suppression (TVS) diodes to clamp expected spikes(they are ongoing at all times and the damage is cumulative). Fast-acting circuit breakers can be used too though not required as they provide additional protection for the transformer, not the trains, there simply is no fuse or breaker fast acting enough to protect your PWC engines electronics as they are current devices, not voltage devices, and let all spikes through unless there is an overload and they trip.

Thanks so much guys,  How do apply a TVS diode with my wiring from my ZW to my lockon on the track?  Also on my PWC NW2 there are two switches on the back deck. Reading the instructions one is supposed to program a number to the engine then set to run. Not having any system in place, am I just supposed to set it to run?...after I have circuit protection that is.  I'm still laying my track and am looking forward to running a couple PWC trains. Thank you all again for your time and expertise. Hank

I sometimes feel bad that I’ve been running my layout on Post War power without fuses for over 20 years, and haven’t blown anything yet.  TMCC, LionChief, Legacy... all still working.

Jon

@Greenbank Hank posted:

Thanks so much guys,  How do apply a TVS diode with my wiring from my ZW to my lockon on the track?  Also on my PWC NW2 there are two switches on the back deck. Reading the instructions one is supposed to program a number to the engine then set to run. Not having any system in place, am I just supposed to set it to run?...after I have circuit protection that is.  I'm still laying my track and am looking forward to running a couple PWC trains. Thank you all again for your time and expertise. Hank

Just set the NW2 to run if you're going to run it in conventional mode. You'll still have the sounds which are an improvement over the originals. Only set to Program when you're ready to run it in Train Master Command Control (TMCC) mode. For that, you'll need the command base and remote control.

For the TVS diodes, if the leads can reach the A and U terminals on your transformer, that's one way. The other way is across the lock-ons.

Rob is right above. TVS diodes are more important than the fast-blow fuses. The voltage spikes are the real demon (from what I've read from him and others).

Breakers and fuses do not protect just the transformer. They also protect the wiring, if sized correctly. A wire rated to carry 7 amps will melt before  a 10 amp breaker trips.

@KOOLjock1 posted:

I sometimes feel bad that I’ve been running my layout on Post War power without fuses for over 20 years, and haven’t blown anything yet.  TMCC, LionChief, Legacy... all still working.

Jon

Me too Jon.

@Greenbank Hank posted:

Thanks so much guys,  How do apply a TVS diode with my wiring from my ZW to my lockon on the track?

Thanks to all for the info and especially Rob for the pics.  I must further expose my electrical ignorance by asking a question concerning Rob's pic.  I see the silver leads with the black diodes ( TVS ? ) that bridge the A and U terminals. It looks like you have them on all your terminal connections and also all Lockons correct?   Is there a rating or wattage amount that I should purchase? And a last question,  what is the black unit with the printing on white that says buss and some ratings?  Keep in mind that these questions are coming from a guy whose wiring looks like spaghetti under the platform because I've never as yet used a bussbar.  So thanks again to  all for your patience and expertise. Joining this group has at least got me into the 80's Lastly, A Merry Christmas, Happy Holidays and have a great safe New Year!  Hank

I'm a believer in TVS like most, but I also like PTCs (polyfuses).  With a PTC you can really cut down on the sparkfest that happens with a derailment or a dropped tool on the tracks.  They shut down things very quickly and are self-resetting.  They are scalable so you can tailor them to your equipment.  Susan Deets is a member here and she has a good write up on them on her web page: https://slsprr.net/technical/CircProt.htm

Excellent discussion here, but how about some part numbers and sources, i.e. "digikey part no xxxx". Thanks

@Greenbank Hank posted:

Is there a rating or wattage amount that I should purchase?

The 1.5KE36CA from Mouser is a good one for the voltages we run trains at.

Rob knows his stuff and you can take his word as solid gold about electronics.  I use the TVS diodes and never had any issues running my DCS system on a Lionel ZW.

Here is a setup that some recommend.  Multiple TVSs are used due to a failure mode that is not detectable.  Besides, TVSs are cheap.

I'll disagree with Rob on breakers not protecting train electronics.  High amperage will toast a circuit board when traces on the board are the only connection between pickup rollers.  Events such as crossing into a shorted power district, where high amps are passing through the pickups,  can be expensive.  I now have Polyfuses in locos.

@Tracker John posted:

High amperage will toast a circuit board when traces on the board are the only connection between pickup rollers...

That is of course a design defect, and has nothing to do with the age of the transformer.

Rob,

Agreed.  Very well said I might add.

Mike

10 minutes back on here and I'm wading into an old favorite subject.

Be generous with your TVSs, and your new trains will be fine.

There are a lot of advocates of fast-acting breakers or(yuck) fuses. Breakers protect your wiring and transformer, not your trains. Any voltage spikes that can kill electronics happen way too fast for a circuit breaker to act, and aside from that breakers react to current, not voltage. If you use fast blow fuses, you'll want to buy them by the case and probably be changing them constantly. Fast breakers can be a pain, especially if you have to manually reset them.

A traditional iron core transformer is perfectly happy supplying a little over its rated current for a while, and can supply large rushes for-for example a motor at near-stall-for a few seconds. The breakers originally installed on postwar transformers will trip in a few seconds in high current situations, like a dead short, and will trip in several minutes if you go a bit over rated current. Check them, and if they meet the spec trip time(it's in the service manuals) use the originals without worry. Rate your layout wiring for at least double the transformers's capacity(i.e. 15A from a ZW) and call it a day. It's served me well for 20 years, and I've never had an electronics failure and don't have to deal with nuisance trips. For the past 15 or so years, my layout has had a pair of ZWs parked on it. They have their original breakers, and a generous sprinkling of TVSs all over the place.

"That is of course a design defect, and has nothing to do with the age of the transformer."

So true.  Do you think the manufacturer would agree and not charge me for a new board?

ADCX Rob, thank you for the part number.I will be ordering a lot of 25 of those TVS's after the first of the year when things calm down. Ben10ben, can you give me a source and part numbers for those fuses and fuse holders you were talking about above? Thank you in advance.

@Tracker John posted:

"That is of course a design defect, and has nothing to do with the age of the transformer."

So true.  Do you think the manufacturer would agree and not charge me for a new board?

Well, not at this point of course. But there are options - cut in a PTC to one(or both) of the roller leads, and that will protect the traces on the board.

Thank you all for the info and diagrams.  We belong to a great group. Here's to a safe and less crazy New Year. Hank