# Lionel KW transformer help.



## Blk69 (Feb 23, 2010)

Hello, been out of the hobby for a while. Inherited two Lionel KW transformers. Was abel to make one working unit from the two. Replaced orginal circuit breaker with a Buss (think this is a busman) 10 amp unit...this is the one you see all over the net.

Connected transformer to my layout and ran a engine for 5 minutes. Bad things happoned. Had a derailment took a long time for the breaker to trip. Wheels on engine have all kinds of pit marks on them. Just not working as it should.

Disconnected KW from layout and connected to a piece of test track. Shorted the center and outside rail with a #18 wire. Wire was wielded to track. A whole bunch of white smoke came out of the KW. Have never used this model before.....assume this is not supposed to happen.

Was hoping this KW would be strong enough to power my whole layout....it seams to strong. Was thinking of installing 5 amp circuit breakers on each channel/seconday to see if this helps. Anyone have a similar experence with this transformer? Looks like nice unit, just prefer to not distroy my trains and layout. Any help/advice greatly appreciated.


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## Blk69 (Feb 23, 2010)

My pervious experence was with a Lionel 1033 transformer. It works well, just expanded my layout and needed multiple transformers.


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## njrailer93 (Nov 28, 2011)

What kind of fuse are you using a glass fuse? I use a fast acting fuse that trips automatically if I have any over current. I use a kW on my layout great transformer


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## sjm9911 (Dec 20, 2012)

Sounds like a bad breaker. Try this site for some info http://www.tranz4mr.com/KW_Page.html


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## Blk69 (Feb 23, 2010)

The original circuit breaker didn't trip at all so knew that one was bad. Truthfully I am at a bit of a loss. My 1033 gives a very small spark on faults and never had anything close to wielding a short. 

My thoughts are getting some sort of circuit breaker to protect the individual channels/secondary's. Each channel is rated at 5 amps, so max I would go was the 5 amps for protection. Issue is that most AC circuit breakers are rated for 125 V, I'm going to be operating at around 15V. 5 Amps at 125 v is around 625 Watts. 5 Amps at 15 Volts is around 75 Watts. Thinking this this maybe an issue leading to very long trip times (if ever). Believe circuit breakers trip on wattage (rated in amps at various voltage rating). If this is the case, than I should be looking for a 1/2 to 3/4 amp circuit breaker.

Need to review my electrical books for reference.


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## Wood (Jun 9, 2015)

*Blk69 posted: My thoughts are getting some sort of circuit breaker to protect the individual channels/secondary's. Each channel is rated at 5 amps, so max I would go was the 5 amps for protection. Issue is that most AC circuit breakers are rated for 125 V, I'm going to be operating at around 15V. 5 Amps at 125 v is around 625 Watts. 5 Amps at 15 Volts is around 75 Watts. Thinking this this maybe an issue leading to very long trip times (if ever). Believe circuit breakers trip on wattage (rated in amps at various voltage rating). If this is the case, than I should be looking for a 1/2 to 3/4 amp circuit breaker.*

That is an interesting formulae for determining circuit breaker size. Is it pertinent? I am not an electrician or that knowledgeable and would like someone to chime in who can affirm Blk69 estimate of breaker size on our layouts operation at >20v.

I have two ZW transformers and one KW. I recently purchased 10 amp 120-250v thermal over load breakers and a porting station. They work very well. The breaker pops in 3-5 seconds after shorting.

Have I made a mistake?

Here are the links to the equipment:

http://www.delcity.net/store/Thermal-Push-Button-Circuit-Breakers/p_539615.h_539678.t_1

http://http://www.delcity.net/store/Blue-Sea-Systems-Circuit-Breaker-Blocks/p_808912.h_808913.t_1


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## sjm9911 (Dec 20, 2012)

Im with you wood, I just followed what others recommend. Grj will chime in. But for now I will post this for some info, http://www.modeltrainforum.com/showthread.php?t=14195


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## T-Man (May 16, 2008)

I just order one, 20-22r from the Train Tender. If you need specs Jeff has a picture of it. It is a modern circuit breaker.


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## gunrunnerjohn (Nov 10, 2010)

Blk69 said:


> My thoughts are getting some sort of circuit breaker to protect the individual channels/secondary's. Each channel is rated at 5 amps, so max I would go was the 5 amps for protection. Issue is that most AC circuit breakers are rated for 125 V, I'm going to be operating at around 15V. 5 Amps at 125 v is around 625 Watts. 5 Amps at 15 Volts is around 75 Watts. Thinking this this maybe an issue leading to very long trip times (if ever). Believe circuit breakers trip on wattage (rated in amps at various voltage rating). If this is the case, than I should be looking for a 1/2 to 3/4 amp circuit breaker.


Actually, each channel of the KW or ZW transformer is capable of delivering the full rated power of the transformer, there is no "per handle" rating.

As far as circuit breaker voltage ratings, those are not a determining factor in trip times, only the current is a factor. The breakers you are evaluating are doubtless thermal circuit breakers, and they only respond to current. The voltage rating is derived from the contact gap and the composition of the contacts, in order to have a higher voltage rating, the breaker has to be able to interrupt a higher voltage, thus more contact gap. Similar reasoning exists for the difference in AC and DC voltage ratings for circuit breakers. The fact that AC crosses zero volts 120 times and DC is a constant voltage dictates a different rating. For DC, the contact gap has to be wide enough to interrupt the maximum voltage without a sustained arc, for AC the arc will be extinguished as the voltage crosses zero volts. 

The "long" trip times are pretty standard for thermal circuit breakers. Here's the curves for the TE W28-XQ1A family, this is a typical circuit breaker found in many hobby transformers, including some of the Lionel and MTH transformers. If you want faster trip times, you need to go for magnetic or electronic circuit breaker designs.

Notice that at 135% overload, it trips in one hour! If you have one of the two amp models, at 175% overload it takes an hour to trip! At 200% overload, it'll take up to 15 seconds for the breaker to trip.


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## captaincog (Oct 7, 2012)

My understanding is that the breakers on the old transformers like the KW and ZW were to protect the transformers first and not necessarily the trains like modern transformers do.


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## gunrunnerjohn (Nov 10, 2010)

Correct, most breakers don't really protect the trains, even on modern transformers. The breaker above is used on most of the MTH transformers, including the Z-4000. The best circuit breaker on any brick I've found is the Lionel PowerHouse 180, it has an electronic breaker that is very quick.


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## Wood (Jun 9, 2015)

Sjm9911, thank you for that link. I think I am good to go with my breakers. What I learned from the link is about transient voltage diodes and I am going to investigate that protection. 

Another value to this hobby and forum. I learn something new every day.


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## sjm9911 (Dec 20, 2012)

Glad it helped! One day you can explain it to me


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## Wood (Jun 9, 2015)

sjm9911 said:


> Glad it helped! One day you can explain it to me


What a team. The blind leading the blind....


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