Postwar ZW Transformer and TMCC

Yes there is a risk.  The PW transformers breaker is not fast acting.  This could cause damage to an engine during a derailment or other situation.  Most folks will put TVS diode protection on the outputs.  See this thread.  Here is another thread.

Also folks added quick acting fuses or modern breakers in line to trip much quicker than the old ZW breakers.

If you are in the market for a new transformer get a modern one with modern protection.

MartyE posted:

Yes there is a risk.  The PW transformers breaker is not fast acting.  This could cause damage to an engine during a derailment or other situation.  Most folks will put TVS diode protection on the outputs.  See this thread.  Here is another thread.

Also folks added quick acting fuses or modern breakers in line to trip much quicker than the old ZW breakers.

If you are in the market for a new transformer get a modern one with modern protection.

I am on a very tight budget; I can only really get $300 every 4 months. It would take my a year to get that $700 modern ZW. I guess I will have to go with thr diode protection. Thanks for the info��

Don't forget to add the modern over current protection too.

slicknick924 posted:

I am on a very tight budget; I can only really get $300 every 4 months. It would take my a year to get that $700 modern ZW. I guess I will have to go with thr diode protection. Thanks for the info��

"Modern transformer" doesn't have to be a $700 transformer!

Since you already have the transformer, I'd recommend you add circuit protection.  You need both the TVS diodes for each transformer output as well as better circuit breakers.

 Here's the proper choice for the TVS diode: 1500W 36V TVS at Digikey

For a circuit breaker, I'd consider something like one of these: CIR BRKR THRM 5A 250VAC, or CIR BRKR THRM 7A 250VAC 32VDC

Thermal breakers are fairly slow to react, so I typically undersize them for the max load, that usually isn't an issue.

Slicknick, just follow the recommendations of Gunrunnerjohn and MartyE.  Your ZW will be fine for your purposes with the TVS and circuit breaker recommendations they provided.

Pingman posted:

Slicknick, just follow the recommendations of Gunrunnerjohn and MartyE.  Your ZW will be fine for your purposes with the TVS and circuit breaker recommendations they provided.

Yep.  I just wanted to make sure if he were to buy another transformer it might be easier and more economical to buy new.  And as GRJ said not all modern transformers are $700.  The options given though should give him peace of mind.

gunrunnerjohn posted:

slicknick924 posted:

I am on a very tight budget; I can only really get $300 every 4 months. It would take my a year to get that $700 modern ZW. I guess I will have to go with thr diode protection. Thanks for the info��

"Modern transformer" doesn't have to be a $700 transformer!

Since you already have the transformer, I'd recommend you add circuit protection.  You need both the TVS diodes for each transformer output as well as better circuit breakers.

 Here's the proper choice for the TVS diode: 1500W 36V TVS at Digikey

For a circuit breaker, I'd consider something like one of these: CIR BRKR THRM 5A 250VAC, or CIR BRKR THRM 7A 250VAC 32VDC

Thermal breakers are fairly slow to react, so I typically undersize them for the max load, that usually isn't an issue.

So will this set up (separate tvs' and separate circuit breakers on each terminal pair) protect against a voltage spike caused when bridging between two separate blocks at different voltages?  

I've read posts on this forum where if one block is at a significantly different voltage from the next (let's say for an incline and decline) the voltage could bridge through the loco and spike as the voltages are added to each other rather that balancing each other out. At least that's how I interpreted it. Is this situation dangerous to LC/LC+ locos? It's my understanding that postwar locos shouldn't have an issue going block to block like this.

Thanks,

JD

The issue with spikes actually gets into a slightly more esoteric discussion about collapsing magnet fields in a coil, etc. but the net takeaway here is to use a good circuit breaker or fuse on each feed and follow that with the TVS protection diode across the power.

So, per this and other related threads, I just got back a "refurbished" Z xfrmr.  I added the external protectiondetailed with these products. Sufficient?  TW

Looks good to me Ted.

So, to further my education at someone else's expense; my old scout growler derails and the circuit breaker pops.  With the TVS at the xfrmr terminals, why doesn't the TVS pop/blow also, or, is it protecting me in another way?  If so, how or what?  How do I know the TVS popped also?  The reset of breaker didn't resolve the short?  Further, is it feasible to remove the shell of say a legacy GS4 and put in a tvs somewhere to provide better protection specifically to the electronics?  Thx in advance again. 

TedW posted:

So, to further my education at someone else's expense; my old scout growler derails and the circuit breaker pops.  With the TVS at the xfrmr terminals, why doesn't the TVS pop/blow also, or, is it protecting me in another way?

It's not really protecting anything on a Scout. You had a current overload... A TVS isn't for that, it's for over-voltage protection. A TVS can be checked/tested easily with an oscilloscope, and not so easily with a number of Rube Goldberg methods that I would not mention in a public forum due to safety issues.

TedW posted:

Further, is it feasible to remove the shell of say a legacy GS4 and put in a tvs somewhere to provide better protection specifically to the electronics?

Yes. Although we're talking about the speed of light and the smallest of distances, the closer the TVS is to the component(s) being protected, the better, especially if it is between the fault and the device. There are diminishing returns though in trying to place one everywhere you might  need one.

Well, it's really more than the "speed of light" Rob.  The key issue is the impedance between you and the TVS.  If the source of the spike is a lot closer to the locomotive and the TVS is on the other side of the loop on the track feed, you'll get a much larger spike through than if the TVS were in the pickup connection of the locomotive.

I spend a lot of time figuring out how to use TVS devices in avionics to best protect circuits, sometimes it came down to minimizing the length of the PCB trace that made a significant difference.  I'm sure that 30 feet of track and/or bus wire would be a lot more significant in terms of protection.

I am a newbie with some problems starting out with the old TMCC. Specifically, another question about using a (rebuilt, properly protected) post war ZW with TMCC: At max output only about 14v is generated. Lionel says this is normal. But is it enough juice to run most trains with the system?

thanks!

cplyons posted:

I am a newbie with some problems starting out with the old TMCC. Specifically, another question about using a (rebuilt, properly protected) post war ZW with TMCC: At max output only about 14v is generated. Lionel says this is normal. But is it enough juice to run most trains with the system?

thanks!

They usually say they require 8 to 18 volts so I would say yes, just enough juice.

OK Thanks!!

I don't know who's telling you that 14 volts is normal for full throttle on the PW-ZW, but IMO they're dead wrong.  I've rebuilt several dozen of them and owned quite a few in the past, and I've never seen one that was nearly that low.  With an 8 amp load, I normally get at least 16 volts out of a PW-ZW.

gunrunnerjohn posted:

I don't know who's telling you that 14 volts is normal for full throttle on the PW-ZW, but IMO they're dead wrong.  I've rebuilt several dozen of them and owned quite a few in the past, and I've never seen one that was nearly that low.  With an 8 amp load, I normally get at least 16 volts out of a PW-ZW.

Wait so let me get this straight, when they are new, they can go 20 volts at full load, bit when they are rebuilt, they can only go 16 volts? Sorry, I'm kind of confused.

Yep Slick, does not compute.

Note that I said with an 8 amp load.  If you have a PW-ZW that outputs 20 volts with an 8 amp load, you have a one of a kind.

gunrunnerjohn posted:

Yep Slick, does not compute.

Note that I said with an 8 amp load.  If you have a PW-ZW that outputs 20 volts with an 8 amp load, you have a one of a kind.

Oh, sorry. I didn't see you saying 8 amps but now I do.

I have a Postwar zw (as you probably know because I created this thread asking about it), and I kind of want to know how much voltage it actually puts out at full load, since I don't have a voltage tester.

Sorry for the confusion! What I meant was that when using the TPC together with TMCC the full output  (at the track) of the post war ZW is 14 V.

take all the TMCC controllers etc. away and my voltameter says my ZW puts out 18 V times four.

Something is amiss in either the wiring or the TPC unless this is with a pretty heavy load.  The TPC shouldn't drop more than about a volt, and the wiring shouldn't really be a measurable drop unless you have a pretty long run to the track.

I'm the last guy you could call an authority, but I'm getting this idea from the following quote, from Lionel's "Trainmaster Problem-Solving Guide":

"Using a Lionel ZW Transformer, only 14 volts go to the track. - There is typically a 4-volt drop when a Lionel ZW is used to electrify a Powermaster."

Chris

Well, I don't know where they get their numbers, but it's not the same place as I can verify on my workbench.

cplyons posted:

...the following quote, from Lionel's "Trainmaster Problem-Solving Guide":

"Using a Lionel ZW Transformer, only 14 volts go to the track. - There is typically a 4-volt drop when a Lionel ZW is used to electrify a Powermaster."

I don't remember reading this, but I do get about a 2 volt drop through a PM-1 with 19 volts in.

Here's the link for anyone who wants to follow along:

https://www.lionelsupport.com/...FAQs/70-0000-000.pdf

The 4 volt drop reference is on page 3. 

I have no idea where this is coming from. The Lionel ZW-C has built in Powermasters. The PH-180 bricks put out 18 volts, and 18 volts is what I see on the tracks and meter even when I use the Cab-1 remote to control the Powermasters in the ZW-C.

Sounds like Lionel is making up an excuse for someone's unique problem. Is someone on this forum actually seeing this 4 volt drop in practice?

George

ADCX Rob posted:

cplyons posted:

...the following quote, from Lionel's "Trainmaster Problem-Solving Guide":

"Using a Lionel ZW Transformer, only 14 volts go to the track. - There is typically a 4-volt drop when a Lionel ZW is used to electrify a Powermaster."

I don't remember reading this, but I do get about a 2 volt drop through a PM-1 with 19 volts in.

Interesting...

George S posted:

Here's the link for anyone who wants to follow along:

https://www.lionelsupport.com/...FAQs/70-0000-000.pdf

The 4 volt drop reference is on page 3. 

I have no idea where this is coming from. The Lionel ZW-C has built in Powermasters. The PH-180 bricks put out 18 volts, and 18 volts is what I see on the tracks and meter even when I use the Cab-1 remote to control the Powermasters in the ZW-C.

Sounds like Lionel is making up an excuse for someone's unique problem. Is someone on this forum actually seeing this 4 volt drop in practice?

George

Yep, I am getting that 4-volt drop, which is why I hijacked this thread to ask opinions on whether 14V was sufficient to run Command Control trains. Now that I've seen these responses I think my situation is possibly/likely due to a wiring mistake on my part. So far I haven't been able to get started with TMCC, beyond the most basic conventional-style running (and the trains are S-L-O-W). I will study my set-up this weekend and start another thread to ask for help if I can't make it work right.

Chris

Based on Rob's response, you should be able to get 17 volts in your setup. Use 14 or 16 gauge wire for power between the supply, Powermaster and track, and keep the leads short.

George

George S posted:

ADCX Rob posted:

cplyons posted:

...the following quote, from Lionel's "Trainmaster Problem-Solving Guide":

"Using a Lionel ZW Transformer, only 14 volts go to the track. - There is typically a 4-volt drop when a Lionel ZW is used to electrify a Powermaster."

I don't remember reading this, but I do get about a 2 volt drop through a PM-1 with 19 volts in.

Interesting...

After reading through this some, let me qualify this a little more - I am referring to conventional operation w/ the PM-1. 19v in from a ZW comes out ~17v out at CAB-1 full throttle setting. If you throw the switch to Command, I don't recall there being that much of a drop.