TIU Protection

Just so you know, a TIU has its own internal fuse and TVS suppressor protection, but it wouldn't hurt to put a 10A fast blow fuse in-line between each of the transformer hot outputs and corresponding TIU hot input.

If you install fuses or breakers between transformer and each TIU input, which is the preferred location, there is no need for fuses or breaker between TIU output and track.  There cannot be more current flowing downstream from the TIU than upstream of it.  The reverse is also true, except for the situation where there is a short inside the TIU.

Fuses/breakers should be the lowest rating that will not keep popping on the heaviest load you might pull, with the limit not to exceed 10 amp.

I certainly am not telling you to ignore the excellent advice from the experts on the Forum when it comes to adding fuses and breakers, but I have operated my TIU and all transformers with no more than the built- in protection.  This has worked for me for over 14 years with no issues and no damage to equipment or engines.  Maybe just lucky!

Ron

The internal protection of a TIU is 20 amps, which to me is too high.  Much depends on the transformer you use.  Some (like Lionel PH-180) have fast-acting 10 (or fewer) amp breakers which provide adequate overcurrent protection) , while the Lionel postwar transformers have inadequate breakers.

@RON ARNDT 091718 posted:

I certainly am not telling you to ignore the excellent advice from the experts on the Forum when it comes to adding fuses and breakers, but I have operated my TIU and all transformers with no more than the built- in protection.  This has worked for me for over 14 years with no issues and no damage to equipment or engines.  Maybe just lucky!

Ron

It depends on your transformers.  I have the Lionel Powerhouse 180 bricks with excellent electronic circuit breakers.  I have never felt the need for more protection as the bricks trip instantly on any overload.  Since the MTH TIU's have a TVS protection diode on the outputs, I also don't add any more TVS protection.

Thank you for the many suggestions. To clarify, I am using 3 MTH Z1000’s and one Z500. I am considering placing a 10 amp manual reset breaker in between each transformer and each TIU input. I have only had one instance where I needed to change an internal TIU fuse. I’d like to prevent having to do that and any other possible issues.

My suggestion would be to consider something like 4A or 5A thermal breakers, they will take a significant overload for some time before tripping.  The Z-1000 is only rated at 6A anyway.  The breaker on the Z-1000 is slow enough that you can pretty regularly blow the 20A fuse in the TIU with direct shorts across the tracks without tripping the breaker.

Ok, thank you…..And gunrunnerjohn, just to clarify, you would only place these 5A thermal breakers between the transformer and the TIU. Nothing needed between TIU outputs and track blocks?

The new breakers can be in either place, one benefit of placing them between the transformer and the TIU is they also protect against any malfunction of the TIU that causes a short across the inputs.

I have blown 2 channels on 2 TIU's using the Z1000 bricks. I have gone back to using my MRC AH601 for power since it breakers operate much faster and have also wired my TIU in passive mode. Still thinking of getting external breakers/reset-able fuses for between the TIU and tracks.

I have read several times that fast blow fuses are a lot faster than breakers.  Just saying.  I don't have any experience with breakers - I used the 10 AMP fast-blow fuses that Barry B.(I think) recommended years ago.  The fuses in the TIU are not difficult to replace by not real convenient either.  Someone posted a great article here about how to hook them up.

If a TIU is wired in passive mode, what overcurrent does a breaker between TIU & tracks protect against?

Walt, I believe that electronic breakers are faster than fuses.  If you go to the fuse manufacturers; web sites, you'll see time-to-blow charts.  On smaller overloads, blow time of a fuse can be awfully long.  Supposedly, an electronic breaker opens instantly; my PH180's breaker opens instantly.

Thermal Breakers are slower than Fast Blow fuses.

Electronic breakers like those found in Lionel PowerHouse 180, ZW-L, and the newest version of the CW-80 are faster than fast blow fuses.  Since those replacement breakers are presently difficult to find, there are two other excellent stand alone options available that are faster than fast blow fuses: PSX-AC and Airpax Instant.

Airpax Snapac "Instant" Hydraulic-Magnetic Circuit Breaker Internal Mechanisms

I always hesitate to comment on electrical things and don't know why I did here, I just had that 'urge' you know?  The topic was big here on the forum about 10 years ago so my "knowledge" is old apparently.

Sorry if what I posted was not currently true.  I have to learn to shut up

- walt

You were mostly right Walt, so don't be so hard on yourself.   In almost all cases, thermal breakers are much slower than fast blowing fuses!  However, the high speed electronic or magnetic breakers can actually beat fuses.

That's not to say that fast blowing fuses won't provide excellent protection, they will.  The issue with fuses is you have to replace them for every overload, circuit breakers are much more convenient.

@walt rapp posted:

I always hesitate to comment on electrical things and don't know why I did here, I just had that 'urge' you know?  The topic was big here on the forum about 10 years ago so my "knowledge" is old apparently.

Sorry if what I posted was not currently true.  I have to learn to shut up

- walt

Walt, I sincerely hope my reply didn't come across as heavy handed.  I used to use fast blow fuses too.  Now that I'm using the Airpax breakers, it's great not to have to keep replacing fuses.

I was hoping to provide some good information I that recently discovered.  I'm glad you brought this up. Thank you.

Steve, I have regular fuses between my zw-c and my tiu. My 180 bricks trip before I blow a fuse, but in any case even though its probably overkill. I still like the extra protection. Seeing this thread makes me want the airpax breakers. That way I never have to have fuses on hand.

I clicked on the link you provided steve to the other thread. Just was confused with all the info. Could you provide the right airpax fuse model for my application? Second when I attach the wires to the airfex fuse. Does it matter which way the fuse is wired?

Think if I get these I will put them in a small plastics project box and neaty label everything and mount it between my 180s and my tiu for easy access to the buttons on the breakers.

Thanks to the poster also on this topic. Otherwise I would have never known about these breakers.

This is a great community. Thank you for all the information. My 5A thermal breakers came today and I’m placing them between bricks and TIU this evening. Thanks again!

@Lionelzwl2012 posted:

Steve, I have regular fuses between my zw-c and my tiu. My 180 bricks trip before I blow a fuse, but in any case even though its probably overkill. I still like the extra protection. Seeing this thread makes me want the airpax breakers. That way I never have to have fuses on hand.

I clicked on the link you provided steve to the other thread. Just was confused with all the info. Could you provide the right airpax fuse model for my application? Second when I attach the wires to the airfex fuse. Does it matter which way the fuse is wired?

Think if I get these I will put them in a small plastics project box and neaty label everything and mount it between my 180s and my tiu for easy access to the buttons on the breakers.

Thanks to the poster also on this topic. Otherwise I would have never known about these breakers.

For the PH-180 you could add the 10A Airpax as an added measure of safety, if ever the PH180 internal breaker happened to fail and would not trip.

Here's the link:

Airpax 10 Amp Instant Magnetic Circuit Breaker   PP11-0-10.0A-OB-V   https://www.onlinecomponents.c...00aobv-10090622.html

@RJR has stated earlier in this thread:

@RJR posted:

If you install fuses or breakers between transformer and each TIU input, which is the preferred location, there is no need for fuses or breaker between TIU output and track.  There cannot be more current flowing downstream from the TIU than upstream of it.  The reverse is also true, except for the situation where there is a short inside the TIU.

Fuses/breakers should be the lowest rating that will not keep popping on the heaviest load you might pull, with the limit not to exceed 10 amp.

If doing this, I would suggest connecting the hot lead out of the PH180 to the Airpax Terminal with the Arrow pointing up (away from the terminal).  Connect the other Airpax Terminal to the Hot side of the TIU Input.

Hope this helps.

this is just what I needed. thanks steve.

Steve raises another good point:  redundancy.  Breakers, like most anything else, can fail.  A second device in the line is a good backup.  To save the cost of an expensive breaker, I use fuses with a rating higher than the rating of the breaker in the line.

As to fuses vs. beakers for the principal protection, a fuse is certainly cheaper than a breaker, but it won't be long before you are nickel-&-dimed to death.

@SteveH posted:

Walt, I sincerely hope my reply didn't come across as heavy handed.  I used to use fast blow fuses too.  Now that I'm using the Airpax breakers, it's great not to have to keep replacing fuses.

I was hoping to provide some good information I that recently discovered.  I'm glad you brought this up. Thank you.

not at all, i didn't take it that way.  but thanks for making sure!

Thanks again to everyone who gave any type of suggestions on the topic…..one more questions while we are rehashing this:

Is there any need to have breakers/fuse protection between the accessory driving transformer output and say the terminal blocks feeding track switches? LEDs and the like are cheap and replaceable. Track switches are expensive. I am using 14v output from a Z1000 for my accessories. Remember, I’m a total newbie. Thanks for your responses!

IMO, decent circuit protection is never a bad idea.  The Z-1000 has a pretty slow thermal breaker, so adding a better breaker or fuses is not a bad idea.

Good thread. Is the same true if using a Z4K that fuses need to be added to the equation?

Thank you.

Paul

I have 5 & 7-amp breakers in the Z400 hot feeds.  They often ipen before the Z4000's breaker.  I like redundancy, and don't usually draw more than 5 or 7 amps, depending on the route.

@Railrunnin posted:

Good thread. Is the same true if using a Z4K that fuses need to be added to the equation?

It's easy to not have enough circuit protection, it's hard to have too much.   So, to answer the question, adding a fast circuit breaker or fuses is not a bad idea.

@SteveH posted:

For the PH-180 you could add the 10A Airpax as an added measure of safety, if ever the PH180 internal breaker happened to fail and would not trip.

Here's the link:

Airpax 10 Amp Instant Magnetic Circuit Breaker   PP11-0-10.0A-OB-V   https://www.onlinecomponents.c...00aobv-10090622.html

@RJR has stated earlier in this thread:

If doing this, I would suggest connecting the hot lead out of the PH180 to the Airpax Terminal with the Arrow pointing up (away from the terminal).  Connect the other Airpax Terminal to the Hot side of the TIU Input.

Hope this helps.

I followed that link, and they look a bit pricier than what I started using after reading about this in another thread a few years ago.  Unfortunately, I can't find the thread or the part number of what I bought, but IIRC they were $5-10 each and about 1/2" diameter and a couple of inches long.   

@gunrunnerjohn posted:

IMO, decent circuit protection is never a bad idea.  The Z-1000 has a pretty slow thermal breaker, so adding a better breaker or fuses is not a bad idea.

The breakers I bought (wish I could find the link) look similar to what's in the Z-1000.  Are they no longer the product of choice?   

@RJR posted:

I have 5 & 7-amp breakers in the Z400 hot feeds.  They often ipen before the Z4000's breaker.  I like redundancy, and don't usually draw more than 5 or 7 amps, depending on the route.

Do you have a photo or link to these?

Edit:  Here's a link to the circuit breakers I'm using based on previous threads - one is inline for each transformer's output, along with a TVS across the terminals.  Are these no longer in favor for protecting engine electronics?  (I paid $2.40 each for these in late 2017; they're now $3-5 each for modest quantities.)

https://www.mouser.com/ProductDetail/655-W28-XQ1A-8