Circuit Protection

I think you will be told that when wired to the transformer it only protects the transformer, not the engines.  To protect the engines you have to wire the tvs into the engine.

RA

Transient Voltage Suppressor[TVS]will protect against voltage spikes downstream of the transformer,including the engine components, if wired across the transformers hot and common terminals. However we assume that wiring a TVS internally in the engine provides the best possible protection for the engine solder traces and fragile wires.

You can connect TVS between the hot and common at about any location on the layout wire runs including railpower terminal strips as shown on the plate-jumpered T-strip below..

Thank you for your informative reply and photos.  That clarified my Z4000 application questions.  However, how does one install this device in an engine.  I don't believe that I've ever seen that part of protection addressed on the OGR Forum.   Has anyone ever shown a wiring schematic and its placement? Very curious as I have a lot of DCS engines and I'm wondering if 9 Volt models, later 3 volt models and new PS-3 engines all have a different placement of the circuit protection device?

Thanks again.

Moke Mike

The newer TIU's have built in TVS' (not sure about older TIU's?). Having a TVS in an engine is added protection and I don't think you can have too much protection? I think some even place them in various places around the track.

I don't have a Z4000, but I am guessing the red light means it tripped the breaker? I am not sure the TVS would help with melting the couplers? I would think melting would be more a function of the breakers, but I will leave that one to the experts.

The solder traces and fragile wires don't need transient voltage suppression/protection, it's the solid state electronic components(literally, any and all components/chips/devices are susceptible to spikes, and the damage is cumulative).  The solder traces and fragile wires are sensitive to over current, if at all. They are rarely the weak link except for physical damage(vibration, handling, normal operational movements).

Locating TVS diodes as close to the device(s) as practical is the key, and it's as simple as(in the case of the recommended bipolar ones) connecting them to the incoming track power(chassis & center rail) at a convenient location within the loco shell.

When you're talking about speed & time for clamping voltage spikes, you can see where it would be advantageous to have the TVS device located between the rails(power source) and the onboard electronics, especially in the immediate case here where a derailment apparently created a situation generating a series of high voltage spikes.

I assume that once the Transient Bridge Suppressor is hit with a voltage spike that it needs to be replaced?  Or does it take the "spike" to ground?  When wiring it in the engine do you have to run a wire to both roller pickups? That may seem like a stupid question, however; I'd like to think of it more as an uninformed question, as I know that when using an ohm meter and checking for continuity between the front and rear pickup rollers, you get continuity at even the most sensitive setting which would seem to indicate there's no internal circuitry in play between the front and rear rollers.

Please forgive me for the uninformed questions as I certainly know how to wire a DCS layout, load any type lash-up, operate DCS with 11 TIU's and replace boards within a DCS and TMCC engine.  I've just never used this type of circuit protection and the current DCS Companion doesn't cover the subject as most layouts only have one TIU and that really reduces the vulnerability to spikes.  I've had lots of derailments in my operating experience and it usually just a red light situation.  The only exception is a derailment while using a DZ1008 relay under a switch and that can take out the 1008 relay.

I can't figure out what the caused the difference in this incident?  I've had lash-ups derail before and the Z4000 always catches the problem. The TIU 5, that had the power is fairly new.  The only older TIU's I'm still running from 2004, are TIU's 1-4.  

Thanks again for sharing your knowledge.

Moke Mike

Are both channels connected to the same Z4000?  If not, transformers may be out of phase.

Originally Posted by mokemike:

The center rail rollers are connected together, they are the same electrically, as you have discovered.

A TVS diode stays in the circuit, takes a licking, & keeps on ticking. It will clamp overvoltage spikes continuously down to their rating, there is probably a way to demonstrate this with an oscilloscope. They do not require scheduled replacement.

Type in "tvs" in search....lots of useful information.

Thanks so much for all of the information. I appreciate your time and help.

Moke Mike

All power to the TIU channels is from the same Z4000. All TIU's are powered with a dedicated Z4000.  All accessory power is provided with the 14V port on those Z4000's. All Z4000's are on the same circuit breaker. All receptacles not on that circuit breaker have the wall plate painted red if they are in the same room. There are no Lionel or other makes of transformers on the layout or in the room.

Thanks.

Moke Mike

Thanks so much for the extremely helpful tip

Moke Mike

I just finished reading most of the "posts" on the the search topic of "tvs". The information I have from previous OGR posts is to use 511-1.5KE36CA, 1500W 36V Bidirect.  I'm not running anything older than P2 or TMCC older than 1999. One post stated to use a 276-1.5KE36CA.  Is the 511-1.5KE36CA the correct "tvs"?

Thanks 

Moke Mike

Mike, your post indicates there are multiple transformers on the layout.  These should all be phased. You

can't rely on the polarized plug to assure proper phasing.  

Manufacturer's part # 1.5KE36CA (Littlefuse is the Mfgr.)

Mouser Part # 511-1.5KE36CA

Digi-Key Part # 1.5KE36CALFCT-ND

Not sure where the 276 prefix one is from?

All the same part. Data sheet available at either link. I prefer Digi-Key, cheaper shipping on small orders.

All wall plugs are on the same circuit breaker in a building that is only 12 years old.  All wall plugs are physically connected to the earth ground receptacle at the circuit breaker panel. All receptacles have been tested with a receptacle tester that shows if a receptacle has reverse polarity.  I'll connected a phase wire to all U terminals on all Z4000's to confirm the entire system and the Z4000's.

Thanks for your comments.

Moke Mike

Thanks for the part number confirmation.

Moke Mike

Phasing is more than the building wiring.  You are correct that transformers should be plugged into the same side of the house wiring,

Even apart from the house connection, the transformers themselves have to be in phase.  For example, take 2 simple transformers.  The manufacturer may have wired either end of the polarized line from the 120-volt outlet to either end of the primary, or may have taken the terminal feeds off either end of the secondary.  Thus, you can't always relay on a polarized plug.  There are transformers in use today which differ within the same model number.  Lionel and MTH have both experienced this.

Thus, one should always check phasing when there are multiple transformers on the same layout, even if one is not used for powering trains, because there is always the chance of a cross-connection.  If you have 2 transformers, each at 18 volts, and the phasing is crossed, a roller pair across the gaps causes a 36-votl short.  On most transformers, not all terminal posts are fed through a breaker.  For example, many post combinations on a Lionel Type R are unbreakered, as would be a short among the A,B,C,D terminals of a pw ZW.

FYI, a short or high currentthrough pickup rollers can ruin the springs in them, and I have had axles get very hot without blowing a breaker, as amperage was within transformer breaker limits.

Something has to be wrong, because if the boards overheated, the current had to be flowing through them, and this normally doesn't happen in a short on the tracks.  This is why I use external breakers with low ratings. Note also that a TVS does not limit current flow; it bleeds off excessive voltage.

I can't see how coupler coils would have burned out, unless the wires to them made contact with something.  Check the locos and see if the wires from the pickup rollers could possibly be touch the wires that feed the couplers.  On several of my locos, they come through the same hole, and could be subject to insulation chafing.

This situation bears careful analysis before settling on TVS as the preventative.

It is difficult to determine if a TVS device has failed. They rarely dead short fail, but can fail to not provide the specified protection.

It's better to have them and just replace them if you think they have had multiple shots. usually, not needed.

What board was in the damaged engine?  PS-2 5V or 3V or PS-3?  There are board faults that occur that cause the lights and couplers to get full DC voltage from the board.  That would be the only thing I can think of that causes both couplers to melt along with lights.

Remember TVS is just clamping the AC input to the device protected based on what is being discussed here.  The PS-2 boards actually have TVS on them, the TIU has them on AC side and also on the Var track FET circuit.  Transformers have them on output.

It clamps voltage spike.  Not a high current inrush from a derailment where chassis ground contacts center rail as an example.

It also won't clamp any DC output side faults, such as a pinched wire, or when a bulb blow naturally.  That is why every so often a bulb that goes bad can take out a fet, or in worst case scenario short a fet and momentarily cause high rush current that can burn a trace.

Every so often I get boards that require a jumped trace after fault.  It happens enough I know where to look for the pinhead burn hole on the PCB.  G

GGG,

If I understand you correctly, then I don't need TVS's on my ZW-C, TIU or PS2 engines?  Even though it wouldn't hurt anything, correct?

FYI,

I read one OGR post that each engine should be addressed separately turning the Clickity Clack off,

That's correct.

The newer TIU's have built in TVS' (not sure about older TIU's?).

All TIUs have TVS protection built-in.

Certainly would not hurt, but if I said not needed that would start a fire storm.  The PS-2 board has a TVS on it, the TIU has output TVS and TVS across VAR channel FETs.  I am not sure what is inside the ZW-C, but I know my Power Houses that feed my ZW-C trip open on the slightest issue.  I Love that.  SO......

I have had one repair of a PS-2 3V board with TVS installed that still failed (shorted audio amp) on a derailment of the front truck.   SO....   of course we don't know what we don't know.   G

The PS-2 board has a TVS on it

Hadn't picked up that info before.  Seems to mean there's no point in installing another one in a loco, save for redundancy.

What about PS3?

This is an update and reply to all that have read or had input for "Circuit Protection". The engine damaged was a 3V version and both boards, couplers and rear lights were damaged and replaced. Using the Forum input, I started by insuring all transformers were in phase. There are ten Z4000's and there were two ZW's a Z750 and a Lionel 1043 transformer. Testing for phase on a Z4000 to a second Z4000 is pretty straight forward as you just connect the TWO red wires from the back of one transformer to the second transformer and connect one wire to both of the black connectors. With both Z4000's on, moving one throttle to greater than 14 volts, causes the second Z4000 volt meter to show the same voltage as the first Z4000.  No red lights or breaker tripped. Repeated the same for the other throttle.  Then using Z4000 #2, with Z4000 #1 at zero volts, advanced the throttle and the #1 should then show the voltage as the #2 throttle is advanced. I also tested for voltage between the red throttle ports and all read near Zero.  All this is covered in the O Scale Companion, 2nd edition, page 68. All Z4000's were in phase. The two Z4000's being tested, that simultaneously indicate each others volts, was not mentioned in the O Scale Companion.  They were, more or less, slaves to one another until the red wires are disconnected for normal train operations. The black wire remains as a phase wire between the two confirmed in phase transformers.

Next the ZW's, which powered some Atlas and Ross switch motors were checked against the Z4000's and they were also in phase with each other and a known good Z4000. Same with the Z750.  However the Lionel 1043, was out of phase, as advancing the throttle while connected to a Z4000 would trip the Z4000 circuit breaker. It also p;roduced a buzz before the throttle on the 1043 reached 8 volts.  I reversed the polarity on the cord and retested and it tested in phase.  Lastly, I tested the Z750 to a Z1000 and they tested in phase to each other, however; the Z750 would not pass the phase test when connected to a known good Z4000?  I tried another Z4000 with the same results and also went to my "carpet central" loading track powered by a Z4000 with the same results.  

Next, I went to several web sites on testing transformers for phase that used either Lionel or MTH as samples. Lionel has a web site that is a 20 minute "how to" video on testing for transformer phase. It has a lot of good explanations about the out of phase waves, however the O Scale Companion had a better test method.  Also, I ran across several web sites that warned not to use a ZW on modern electronics engines as the red light on a ZW is an indicator controlled by a thermal breaker to protect the transformer and not the engines or track. Putting a screw driver across the rails may take the thermal breaker from 5 to 11 seconds to trip as the ZW gets too hot.  In the meantime, the transformer can be similar to a "welder". Discovering that, I uninstalled both ZW's and powered their items with the 14V port on the Z4000's.  The 1043, which was out of phase, has no circuit breaker of any kind. I uninstalled that item and powered its items with another Z4000 14V port.  The distance between the switches and the Z4000 was over 40' and that is why the supplemental ZW's and 1043 were in use.  

I set the Z750 aside and added a Z1000 that passed the Z4000 phase test. It's powering some Atlas turnouts that require a voltage higher the 14V.  All transformers now have a phase wire connecting each transformer to one another for all ten Z4000's and the Z1000.  

I can only conclude that the lead engine of the lash-up, that was damaged during its de-railment, that allowed the wheels to contact the center rail, wasn't protected since the 1043 transformer was out of phase putting combined voltage on the track to about 32 volts during the short, and no circuit protection when using a 1043 for a period just long enough for the Z4000 to trip off, but leaving the 1043 still producing voltage?

The Lionel video on phasing did an excellent job of explaining that any transformer out of phase, regardless if it's powering switch motors, accessories or the track, has dire consequences during a short.  The web sites describing the old ZW's that have a thermal breaker, have no place on a layout with modern electronics.  You can always install an in line after market breaker on the ZW on the red connection, but why trust that to work fast enough when the consequences of it not working can easily exceed $300, which is almost is the price of a modern brick or transformer? I'm sure an in line circuit breaker would work, but I don't have the knowledge to insure that is the case. I'm talking about 

track and engine protection during a short and not transformer protection.

I'm not a graduate of any electrical engineering school, however; I've learned a lot from this incident and from the help of the Forum members.  I just read the latest post and it seems the tvs's aren't required either when using Z4000's newer TIU's and MTH, Lionel or other modern electronics engines?

The only other powered transformers on the same circuit now, are three cordless phone 6V transformers that do not have a polarity plug.  The same, with three 6V tranformer for the transmission of signal to a closed circuit TV system.  I'm not sure how to correctly handle those.  There is a second circuit in the building, in the same room, that is on a different leg of the 220V service.  Those outlets have the cover plates painted red. I could power all those 6 volt transformers with extension cords to their transformers if required?

Please feel free to amend any actions or conclusions, as I just want to get the layout running again and do so with confidence that another derailment of an engine won't damage the engine.  As I look back in retrospect, I've had several freight car derailments, but rarely an engine derailment that actually allows the wheels to touch the center rail. 

Thanks.

Moke Mike

Phasing is only an issue if the transformers can be put in parallel. This can happen if 2 or more transformers are hooked to the same loop and pickup rollers bridge the center rail; plastic pins or gaps. Paralleling transformers,even identical ones is not a good idea IMO. 2 bricks for example would have 20 amp potential and would generate a good spark during an overload,even with fast acting breakers. Breakers protect in general the wire and transformer,not the equipment run. An added thermal breaker to a PWZW is adequate to protect the wiring,assuming it is properly wired. If used, small branch lines may need additional protection.

You can not really phase a Z750 with a 1043. You can in the sense of polarity that both waves are positive or negative but the sine waves are a different shape and would not superimpose on a scope. Not good for the 1043 if they are in parallel.

Quote

"I'm not a graduate of any electrical engineering school, however; I've learned a lot from this incident and from the help of the Forum members.  I just read the latest post and it seems the tvs's aren't required either when using Z4000's newer TIU's and MTH, Lionel or other modern electronics engines?"

TVS protection is needed regardless of transformer used IMO. Voltage spikes are potentially generated off any equipment run with inductance. If anything, I would think older transformers with their iron cores would be less prone than a modern ones. The TIU has a 33 volt TVS in it,so it is protected. Further TVS units would not hurt anything and give spikes additional paths to take. PW equipment is not prone to spike damage but anything with PC chips are,including accessories.

As far as the Lionel phasing video,it is at best misleading. You can activate accessories with 2 out of phase transformers as long as they are not in parallel. Sharing a common is not an issue.

On my layout I share a common with a DC circuit and run hundreds of relays off it to activate accessories and route trains. I have not experienced any issues with this. Certainly AC and DC current can not be phased.

Dale H

RJR,

   I can't remember who advised me that the P2 engine boards had a built in TVS, I do believe it was George (GGG)when I talked to him about sending some parts to Bill for fixing my DCS hand held remote Control, I probably should have talked about it on the forum, it's the main reason I only use the TIU TVS when running my P2 engines, Barry turned me on to this TIU TVS years ago.  It is my understand the P3 engines are safe guarded in the same manner, however I own no P3 engines at this time, so I can not speak from actual experience.  Maybe George will come back and let us know for sure.

PCRR/Dave

Dale, some of your reply was a little over my level of electrical knowledge, however; 8 of the 10, Z4000 transformers are powering track/tracks that are separated by a cut rail or a plastic center pin. A lash-up of two or more engines is often on two different transformers, at the same time, as it transitions from power block to power block as it moves around the layout. I would assume that phase would be very important in that configuration.  The derailment happened about 8 feet beyond such a power block transition.  The 1043 transformer was powered at the time of the derailment and was out of phase. It was plugged into the same circuit breaker in the building service panel as the Z4000's that were powering the engines at the time. From what I could determine from your reply, the 1043 is not compatible with the Z4000's. 

Thanks for your input

Moke Mike

Mike

All transformers are compatible with each other as long as they are not somehow circuited in parallel. They can all share a common,assuming the common bus can handle the load. Your house is wired so half is out of phase with the other half,with a common return. 

The problem is that you are putting them in parallel via the pickup rollers. This is like a sometimes arrangement.  Small wires in lighted cars between the pickup rollers are inadequate to carry a large amount of current. These should be protected with a polyfuse or opposing diodes. This does not completely solve the jumping problem since there is still the rollers on the engines and a single roller could fall in the gap connecting them. 

If paralleling transformers,then they should be identical and set at the same voltage. If they are not, and if they are the PW type,they can bleed back into one another causing damage. When paralleling transformers, indeed phasing then also becomes an issue.  If paralleled  opposite phased,the breakers may not even trip,depending of the transformer design and a lot of damage could occur.

Again this is a sometimes arrangement you have. I don't know your layout conditions. Lets say you have 4 transformers connected to the loop, each capable of putting out 10 amps each. If the stars line up right and 3 trains connect the 4 together,you have 40 amps potential if a derailment occurs at that moment. Even with fast breakers,and 4 would have to trip, this is a lot of potential,even at 18 volts. 18 volts at 40 amps is 720 watts,the surge may even be greater. Bury a 100 watt light bulb in some insulation and light it and see how hot it gets very fast. Your potential is 7 times that,OK for a short duration but still what you have is a mini arc welder. 

If I were going to parallel transformers,something really to avoid,I would do it like it was full time and run them all through super fast breakers or maybe 1 single breaker and use beefy bus wire. This may result in nuisance trips though. 

The sine waves generated by power companies are sinusoidal. On PW type this is replicated by inductance through the windings. The Z750,to my understanding puts out a chopped type sine wave,made with solid state circuitry. The two can be matched as far as both negative or both positive together each cycle, but the waves will not line up or transpose. In each millisecond in time they would be different potentials.  As a matter of fact a Z750 would not line up with a Z4000 either or maybe even another Z750. There are variations in manufacturing.  The Z4000 puts out a pure sine wave but made with solid state circuitry. 

To sum up paralleling transformers is not a good idea IMO. It should be avoided. If jumped by pickup rollers it is not avoided.  2 diodes or a polyfuse between pickup rollers in lighted cars can avoid some of the problem but not all of it.

If transformers are put in parallel,adequate circuit protection is needed and they should be identical type waves and set at identical potentials and of course in phase. Modern transformers,depending on design  may not bleed back into each other but PW types will.

Simply sharing a common is not an issue as far as the electrical circuit issues.  I don't think it messes up the DCS signal but I do not know much about DCS. 

Dale H