Possible use of TVS diodes recommended for model railroads that have engines with sensitive control electronics.

As I expect that you know, every TIU already has a TVS installed on each of its 4 channels. The only reasdon to add  any additional TVS protection is due to operating in Passive TIU mode.

In any case, they shouldn't be necessary on the input side of the TIU, at all.

This and a whole lot more is all in “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at OGR’s web store!

Since the TIU has a TVS across every output, why are you bothering with duplicating it?

For maximum protection, I have always advocated adding the TVS directly to the locomotive (and tender for Lionel engines with a wireless tether).  The best place to add transient protection is as close as possible to the item being protected.

John,

Since the TIU has a TVS across every output, why are you bothering with duplicating it?

Because he operates in Passive TIU mode, as he noted in his post at the top of the thread.

Barry, the TVS is directly across the output terminals, so it's there for passive or active mode.

Personally I think you went overboard with the use of TVS diodes at every terminal connection. But if it makes you feel safe then that's what counts. The TVS units provide momentary voltage spike protection and that is what harms the newer electronics.

With the computer a battery back-up is definitely needed because of possible power drop outs.

I lived in Georgia for about 3 years during the 1990's and had my water pump get an indirect hit from a lightning bolt. Knocked out the fuses at the pump and the main fuse box, my wife said it sounded like a double barrel shot gun going off when it happened. I was fortunate as I had to replace only 4 fuses and call the water pump repair man out, nothing else was effected, water pump was fine after replacing the fuses.

As far as lightning protection for your house; it's mainly a hit or miss(either it hits you or misses you) with the lightning bolt! Power surge protectors are useless against the full voltage of a lightning bolt. Power company protection mainly protects you from feedback from a lightning strike to a power line, and again is not 100% guaranty against a lightning strike, as nothing will guaranty 100% blockage.

Lee Fritz

The OP might be a little over the top, but I always figure you can never have too many TVS's, and since they have no downside, why not? I always install them at the terminals of every transformer output, at the least.

Rod

I also use a voltage regulated UPS in front of my TIU.

I am just getting into command control and, just for the heck of it, I am doing nothing beyond using the manufacturers products as intended. I don't have any really high-value stuff, so the exposure is not great, but I just want to see what happens. I suspect that we "over-worry" most things electrical. However, I am not using any PW transformers, modern power for modern locos is kind of my theory.

My track supply is all PH-180s going through Legacy Powerhouses. No accessories on the PH-180s, just track. NO added circuit beakers, fuses, TVSS or anything. PH-180s are plugged into a computer power strip, the type that sits under a monitor. It may have an MOV in it but I don't know. Uncouplers are connected through ASC2 modules, but they have their own Z-1000 transformer that also feeds the Fastrack switches and a bunch of PW accessories. There is an undersized PTC fuse in the uncoupler feed to protect against "stuck buttons." Command is via Cab/Base-1L. 

Right now I have Legacy, TMCC, ERR conversions, LC+ and PW that I run intermingled in all combinations. No DCS. Stay tuned.  I'll be the first to 'fess up when something fails.

"I don't have any really high-value stuff, so the exposure is not great, but I just want to see what happens. I suspect that we "over-worry" most things electrical."

You may be right to an extent, but most of us become believers after an engine or 2 go fritzo for no good reason. Been there; done that!

Rod

John,

the TVS is directly across the output terminals, so it's there for passive or active mode.

I learned new something today - thanks!  

Willy,

I also use a voltage regulated UPS in front of my TIU.

I have the entire layout powered through a large APC UPS. An identical UPS protects the train room's service bench.

Living in Florida, "the lightning capital of the world", it's prudent to do what one can to protect against lightning-inspired, and other, power surges.

Couldn't agree more Barry!

Rod

The best way to protect electronics from lighting strikes is to unplug them when not in use and do not operate them when lighting or storms are present.  All my vintage stereo gear is unplugged when not in use.  Cheap switchable power strips makes this easy with one plug to unplug for each system.

I learned this the hard way in the 1970s when a lighting strike fried my stereo receiver.

Charlie

If the TVS is so cheap, why don't the engine manufacturers put them on all engines and tenders.  It would save both the consumer and manufacturer a lot of heartaches. Warranty Returns cost manufacturers to ship the item back to the buyer.  ... Or am I missing the point. It's 1:49 in the morning. I'm awake, but my mind is sleeping.  John Rowlen

Barry Broskowitz posted:

As I expect that you know, every TIU already has a TVS installed on each of its 4 channels. The only reasdon to add  any additional TVS protection is due to operating in Passover TIU mode.

 

I know that some appliances sold in Israel have a Shabbat mode.  I am impressed that MTH built a Passover mode into the TIU.

Now I know I can safely operate my layout with chametz-free power. 

I know that some appliances sold in Israel have a Shabbat mode.  I am impressed that MTH built a Passover mode into the TIU.

Now I know I can safely operate my layout with chametz-free power. 

LOL!

Darned spell checker! 

Why not just intercept the problem at the source by plugging in your transformer to a surge protector.

I have 1 TVS on each loop. Plus I fused it.

As for lightning, speaking as a victim(house)nothing will stop lightning. If there's a storm, unplug it. All my train  plugs are out of the wall unless I am running them.

Why not just intercept the problem at the source by plugging in your transformer to a surge protector.

The source isn't  necessarily going to be the house circuit.
The TVS should be as close as possible to what is to be protected.
Ideally, inside the locomotive.
Which gets back to the question: Why aren't the manufacturers including TVS diodes in their circuits?

"The TVS should be as close as possible to what is to be protected."

Actually you could argue that the TVS should be as close to the source of the voltage spikes as possible. Since the spikes are generated by the sudden start or collapse of current flow in an inductor (ie: transformer winding), why not put them at the transformer connections, to arrest the spikes at the source, at the very least?

Rod

True enough, if you can identify all the possible sources of transients. Unfortunately, a lot of layouts use track-powered switches and accessories, and the constant-voltage track in command mode makes this even more tempting, witness the Lionel Plug and Play stuff. I have never studied the effect of the inductance of the track itself, it might be a factor in the case of a derailment but I doubt it at the moment.

This has been discussed for ever, is this a new revelation?  I use K-line super snap and every terminal track has built in surge protection with cap and TVS.  So does TIU, so does PS-2 and 3 boards and the PH bricks have the fastest breaker.  I have not lost one engine electronic on my layout.  And I have had some spectacular derailments running conventional and command combined on the 4 loops.  G

TVS's are always a good idea, however..

As mentioned, lightning should be a non issue. Unplug your trains when not in use and don't run them during a thunderstorm.

Also mentioned, when running MODERN TRAINS, use a MODERN TRANSFORMER with a modern circuit protection.

Lionel 180w bricks are about as good as it gets. I had sparks that would scare a welder when I ran 2 in parallel and had a derailment. Never a board failure.

 Ill hazard a guess that the folks that run those "cool, inexpensive, retro postwar transformers"  are the ones most often " smoking boards" on modern equipment.

It's always the same people posting,  and they " smoke" boards on multiple locos.

Penny wise, dollar foolish as they say.

Accessories with solenoids or 'vibrotors' can apparently throw nice electrical spikes into your wiring.

I had multiple failures of DZ-2500 switch machines that were on the same bus as the accessories, before I installed a TVS + RC filter on the offending accessories.

What TVS did you use. And do you have some info on the RC filters?  Thanks,

Mark

I know that there are legitimate surge issues, but, yeah - why would your layout be plugged into the power grid when you are not using it? (This computer is unplugged - DSL cable cable as well - when not in use, too; I do fudge with the computer in the winter sometimes when we do not have thunder storms, I'll admit.)  

Why doesn't OGR Forum take all these comments and compile it into an article of "Tips to Protect Your Model Railroad" ?  I am building my fourth layout in the "Age of the Computer Board and the Power Surge."  My life experience was with the Lionel of my Youth.  I am now sixty-six-years old and from a different time when dinosaurs roamed the Earth.  A helpful "Electrical Check-List" would  be a great help to geezers like me.  I like my eggs fried, not my toy trains.  Sincerely, John Rowlen

I just realized, even though I have been unplugging my transformer and it is in a Breaker-equipped Power Strip, I have been charging my handheld 990 Remote in its base that has a communication wire to the track that I had not been disconnecting.  ... I will now disconnect the communication wire from the base when I am charging the 990 Handheld Remote.

I bought TVS units from Roy at royztrains.com.  They are $12 a piece.  They use a simple, but highly effective combination of a zener diode and a resistor.  He provides a nice description of his TVS units on his website.  They are built similar to the early QSI PowerGuard units, which QSI wanted everyone to use after having many board failures from spikes, surges and certain transformers that didn't play well with sensitive electronics.  Power Guard units used to have a light that flashed every time it clamped a spike.  You'd be surprised how many times that light will flash on a normal run session due to the very nature of rolling inductive loads (locomotive motors receiving intermittent power from rollers dragging on tracks). 

Basically every spark becomes a spike!  So clamp it!

Adam

Dennis LaGrua posted:

Why not just intercept the problem at the source by plugging in your transformer to a surge protector.

That's pretty simple, because it's more than even money the transient is generated within the layout.  Any coil that has an electric current passing through it and then interrupted can generate a high voltage spike.

Could the Uncoupling Tracks in my layout be doing this as my engines roll over them?

Probably not, but they certainly can when you use them to uncouple something.

I have sent two new Lionel 21" Sound Station Diners back to Lionel that had sparking trucks that even tripped the ZW-L breaker.  I have a couple other 21" passenger cars with trucks that will spark occasionally.  Could this sparking lead the failure of boards in my Lionel Legacy engines? I am sending a Legacy Southern Pacific AC-12 that had pinches wires back a second time to Lionel because potentially a motor board has failed.  ...   Another Lionel 21" NYC ESE passenger car has badly  pinched wires that I can see the silver wire through the cut in the black insulation.  I have sent both of my NYC ESE J3a #5426 and #5429 that pulled these 21" passenger cars to Lionel for service. Could the sparking passenger cars they are pulling be contributing to the NYC J3a engine's board failure?  

PRR Mark posted:

What TVS did you use. And do you have some info on the RC filters?  Thanks,

 

Here's a thread that will help with the TVS parts.

PTC and TVS - Some Commonly Used Sizes and Part Numbers

I don't have the info on any RC filters, but if someone posts the info I will be happy to add that to the PTC & TVS list so everyone can reference it.

I did not use a TVS. I did not use a PTC. I don't even know what they are, but I am happy you do.   I did use UPS to ship 15 engines back to Lionel, five of them for a second time, mostly mechanical or cosmetic issues.   If these trains are so sensitive, why don't the manufacturers warn you not to buy them? 

I use a ZW-L on a circuit breaker power strip and a 990 Remote. (Three of them, (not at the same time) all with mechanical issues, all going back to Lionel, two for a second time.  The 990 Remote vibrates after I stopped my engine. The vibration turns the RED KNOB to speed 2 or 3 on its own, and the engine creeps forward.)  It could be that the 990 Remote is sending power to an engine that doesn't have enough current to move, burning the board.  Is this possible?  I have all wires carefully running into MTH 1014 Boards that are daisy chained to my ZW-L  with surge protection.  What is a TVS and where should I install it?  I have 500 wire drops from Atlas Terminal Joiners. I will NOT be adding 500 of anything to my layout. One , two, maybe. Please tell me where to "stick it", the TVS that is.

John Rowlen posted:

I did not use a TVS. I did not use a PTC. I don't even know what they are, but I am happy you do.   I did use UPS to ship 15 engines back to Lionel, five of them for a second time, mostly mechanical or cosmetic issues.   If these trains are so sensitive, why don't the manufacturers warn you not to buy them? 

I use a ZW-L on a circuit breaker power strip and a 990 Remote. (Three of them, (not at the same time) all with mechanical issues, all going back to Lionel, two for a second time.  The 990 Remote vibrates after I stopped my engine. The vibration turns the RED KNOB to speed 2 or 3 on its own, and the engine creeps forward.)  It could be that the 990 Remote is sending power to an engine that doesn't have enough current to move, burning the board.  Is this possible?  I have all wires carefully running into MTH 1014 Boards that are daisy chained to my ZW-L  with surge protection.  What is a TVS and where should I install it?  I have 500 wire drops from Atlas Terminal Joiners. I will NOT be adding 500 of anything to my layout. One , two, maybe. Please tell me where to "stick it", the TVS that is.

John; in your case the likely easiest spot to add a TVS is at each MTH 1014 terminal block, right from the red binding post to the black. You will likely find that you have way less incidence of electrical failures afterward. The one you want is the 1.5KE36CA as referenced in the link provided by RTR12 above. The TVS simply clamps any voltage transient in excess of 36 volts, so that they cannot fry sensitive components on the boards in your engines. Very simple concept. They are less than 50c a piece, and there is no downside to them.

Rod

Dennis LaGrua posted:

Why not just intercept the problem at the source by plugging in your transformer to a surge protector.

Dennis; with all due respect, a surge protector will not help with transients downstream of the transformer, because they are generated by a collapse in current flow in the secondary coil which supplies power to your layout. you still need TVS's IMO even with a surge protector.

Rod

Any form of TVS can help reduce electronic failure in the trains.  What is critical is the placement, the most effective is to put the TVS after the transformer, TIU, Lionel Brick, etc so that a transient  created on the operating tracks is clamped.  I use the Royztrains item as it is easy to install and works!  Other solutions also exist.

The best place for the TVS is right at the circuit being protected.  Since that's the individual locomotive electronics as a rule, that's a lot of work if you have a ton of locomotives.  Next logical place would be at the track connection, and putting a couple at track drops wouldn't hurt.