TVS diode suppressors

Either way, electrically equivalent.

At the transformer, will protect all powered equipment downstream. On the track, will protect equipment powered in parallel(so if you shut down that track to operate in the yard, the protection won't be there).

They are pretty cheap, I wonder if it makes sense to put a few of them online?

It does make sense.

Thanks guys, I’m going to place at transformers and then some. Will recommend same to my friend as I ordered 25 which should be enough.

Joe---something you might want to take a look at.

I distribute railpower from transformer to rails via plate-jumpered Terminal Strips and mount a TVS on each strip.  The photo below shows an example of a 6 position strip with the HOT (green) and Common(white) conductors* from an 180 watt Powerhouse connected and energizing six screws. Thus, 5 pairs of Hot and Common screw heads are available to connect for soldering wire runs to the rails at diverse points on a single power district.

I also mount TVS at the 12 position Layout Distribution Strip at the Power Center that organizes and distributes to the various power district T-strips. 

* I remove all plugs from my PowerHouse transformer output conductors and solder on spade lug to accommodate virtually all threaded  connecting points on transformers, TIUs etc.

I put mine on the TIU outputs and change them out every four or five months.

Kerrigan posted:

I put mine on the TIU outputs and change them out every four or five months.

Is there a reason to change them out?

The TVS Diodes do wear down over time. Since they are inexpensive, some elect to use multiples per circuit and replace them on an annual or similar schedule. Very cheap insurance against one of the more common causes for fried boards.

Can anyone supply a part number and source of the TVS items please. Thanks.  Joe

For our trains we recommend two models of TVS:

For power supplies in excess of 18VAC use the 1.5KE36Ca diodes.

If you only use supplies that are limited to 18 VAC then you could get by with 1.5KE33Ca diodes.

They can be found on Mouser, DigiKey and similar electronics providers as well as the 'bay.

Guitarmike posted:

They are pretty cheap, I wonder if it makes sense to put a few of them online?

If a TVS fails, it can fail shorted or open. If it fails shorted, you will know it right away if you have a good breaker! If it fails open, you will not know about it, and you will have no protection. So having several do make sense, because if one fails open, the others are still protecting.

If you are installing them in an engine, then I would recommend two in each engine for the same reason. You will have a backup TVS in case one fails, with the added bonus that your protection travels with you if you take any of your engines to a friend's house for a play date! Also, I like the idea of protection right on each engine because that puts the protection as close as possible to the place where it's needed, in this case the sensitive and expensive boards in your engine. I can't prove that there's an electrical benefit to installing them in an engine vs, at the transformer, cuz like Rob said, they are "electrically equivalent", but my gut tells me that it's better.

George

Thanks BMORAN4!   Joe

I've had a whole-house surge protector put on my main panel. Do I still need TVS's?

Wally

Cho Cho Wally posted:

I've had a whole-house surge protector put on my main panel. Do I still need TVS's?

Wally

YES. 

TVS diodes across transformer outputs protect the train electronics from power surges caused by the trains themselves (i.e. derailments etc.).

How does one test a TVS, specifically a 1.5KE36Ca diodes; without destroying it?

You would need to do it on a scope, coming up with a method to induce a spike.

This is not meant to be disrespectful.

So I have a component - a TVS that inoperation has 2 failure modes, open and shorted.  If it has failed open my on test is with a scope.  If it fails open it provides no protection and in operation I willhave no indiction that it has failed.  If it shorts is caused my breaker to trip.

Do I understand?

I too was wondering about a failed open situation resulting with no protection. Would it be possible to put a light bulb in series with a TVS? Just a thought.

TVS components are difficult to test for function.  The test involves a current limited variable voltage to plot the breakdown voltage curve. This can obviously only be done out of the circuit as the voltages required would be very likely to cause more damage than just leaving an open TVS in the circuit.

As for determining if they're open in a circuit with a monitor, there is no effective way to test for that condition.  Obviously, a light bulb in series won't work as in normal operation the TVS is not conducting any current.  The only thing the lightbulb will do is increase the impedance through the part making the TVS less effective.  However, it would indicate a shorted TVS by lighting.

The TVS is not like an MOV that degrades for each spike, they normally have a pretty long life.  Also, the predominant failure mode is shorted, so the chances of having an open TVS aren't that great.

If you're worried about them being open and not protecting the circuit, put a couple in parallel, you are increasing the odds that at least one is intact.

GRJ, is there an issue created with capacitance if to many TVS's are added to a layout?

It is possible to affect the DCS signal with too many TVS diodes across the track.  Each TVS exhibits about 1500pf of capacitance.  If you have then in every locomotive and have a lot of them powered on one TIU channel, you'd probably see some attenuation of the DCS signal.

@gunrunnerjohn posted:

It is possible to affect the DCS signal with too many TVS diodes across the track.  Each TVS exhibits about 1500pf of capacitance.  If you have then in every locomotive and have a lot of them powered on one TIU channel, you'd probably see some attenuation of the DCS signal.

John, which TVS diodes should I buy? Uni-directional or Bi-directional?

Bi-directional ones such as the 1.5KE36CA or 1.5KE33CA as recommend above...

Yes, bi-directional TVS is for AC, the unidirectional ones are for DC.

Thank you both!

@gunrunnerjohn posted:

The TVS is not like an MOV that degrades for each spike, they normally have a pretty long life.  Also, the predominant failure mode is shorted, so the chances of having an open TVS aren't that great.

I agree with John.

To add to what John said, if you have inadequate over current protection (breaker) then the TVS will first short, but may open due to excessive current through the TVS. Fast breakers will should prevent a TVS from going open.

(Pack of 20 Pieces) Chanzon TVS Diodes 1.5KE33CA 1500W 33V DO-201AD (DO-27) Bidirectional Channel 1500 Watt 33 Volt: Amazon.com: Industrial & Scientific

Thanks

I have a copy of an extensive article on surge protection written by Frank Quall’s a member of the DC Highrailers.  In it it he describes testing a number of products that were sold to provide surge protection that did not meet his stringent criteria for protection.

The article also has instructions on how to make a module that would let you know when a spike occurred.

As soon as I get back from vacation I’ll scan it in and e-mail it to any one who is interested.  I’ll also try to scan it in to this forum.

I'm in Wayne!!  billcianci@gmail.com please & thank you!

@WaynePa posted:

I have a copy of an extensive article on surge protection written by Frank Quall’s a member of the DC Highrailers.  In it it he describes testing a number of products that were sold to provide surge protection that did not meet his stringent criteria for protection.

The article also has instructions on how to make a module that would let you know when a spike occurred.

As soon as I get back from vacation I’ll scan it in and e-mail it to any one who is interested.  I’ll also try to scan it in to this forum.

Please forward the article to me as well.  Thanks!!

.

I would like a copy as well.

Thanks much,

Perry

@WaynePa posted:

I have a copy of an extensive article on surge protection written by Frank Quall’s a .. I’ll scan it in and e-mail it to any one who is interested.  I’ll also try to scan it in to this forum.

Wayne, thank you for the offer.  I'm also interested in the article.  My email is in my profile.

Thank you, Steve

One more, please if not posted on the forum. Thanks!

I would like a copy.

I would appreciate a copy as well.  Thanks.

Mark

The search engine is a great tool.  Stan's Track Spike Detector.

We would like one too. Thanks so much.

I would like one too. Thank you,

Bob