# Protecting a Lionel KW transformer.

I am using a Lionel KW transformer to power building lighting and other accessories.

For the lighting, I am using the A and B variable outputs as they give me the versatility to adjust the brightness according to what I need at the time.

I measured the output of the A-handle for a small city block with 10 buildings, and the brightness I liked was with a setting of 14 volts, and the resulting current draw was 3 amps. This is about 42 watts, which I guess would be OK for the KW, but I am not sure.

As most of you guys know better than I do, the KW has a rating of 190 watts, consumption I believe; but I really do not know how this is allocated among the two variable and several fixed outputs.

What would be the appropriate rating for a fuse or circuit breaker for the KW variable A and B variable outputs?

Thanks!

Alex

Happy O-Gauge Railroading!

Alexander Müller

See My Mostly Completed Layout Here

OGR  forum member since 26 January 2008

Original Post
Alex, the KW is a single transformer unit and the output is rated at 140W or 10amps. So that would be the Maximum.

Possibly a 10amp quick blow fuse especially if you intend to keep under 10amps. G

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Protecting your transformer and protecting your layout from fires are two different considerations. If you do use a fuse or circuit breaker at 10 amps, consider whether your downstream wiring can carry this amount of current safely. I recommend breaking the accessory feed into smaller subgroups that are fused properly for the actual wire size at the load.
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GGG, Dale -

So a good approach would be to divide the load(s) that the KW will supply, and select the proper breaker or fuse for each output.

Then, the sum of all the expected current draws times their individiual voltages should not exceed 140 (watts), correct?

For example:
Variable A not to exceed 14 volts: Large area building lights, 4-amp breaker or fuse = 56W
Variable B not to exceed 14 volts: Small area building lights, 2-amp breaker or fuse = 42W
Fixed 14v = Operating accessories, 2-amp breaker or fuse = 28W
Fixed 20v = Turnouts, 1-amp breaker or fuse = 20W

These add up to 146 watts, but since the operating accessories and turnouts are intermittent, even if they all were to draw the maximum current simultaneously, it would be for a very short interval.

Is the above about right, ball-parkish speaking?

Thx!

Alex

Happy O-Gauge Railroading!

Alexander Müller

See My Mostly Completed Layout Here

OGR  forum member since 26 January 2008

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Alex,
You are headed down the right road, remember however unless you have had your KW rebuilt it has some time and wear on her, try not to stress the transformer to the max load. I used part of my KW in the same manner you are
going too. I kept the lights some what dim and everything looked real cool on the layout and it never hurt the KW, I even powered some of my old 072 Lionel
switches with her, I did however put LED lights in the old Lionel 072 switches. Old KW & ZW transformers definitely need 10Amp breakers in front of them for any use on a DCS controlled layout.
PCRR/Dave

Never worry about what other people think, be strong and walk in the way of the Lord.

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quote:
Originally posted by Dale Manquen:
Protecting your transformer and protecting your layout from fires are two different considerations. If you do use a fuse or circuit breaker at 10 amps, consider whether your downstream wiring can carry this amount of current safely. I recommend breaking the accessory feed into smaller subgroups that are fused properly for the actual wire size at the load.

Well Hallelujah,

Finally someone says it in a sentence and says it as simply put as it gets.
You don't run 16 gauge wire from your transformer for a buss for building lights then branch of with 28 gauge wire and fuse it with 10 Amps(Just an example) Why?
Because the 28 gauge wire will now be the fuse and if something goes wrong inside one of those buildings the fuse won't blow because the wire is smaller than the fuse that you think will protect it.

Oh you can run the 16 gauge wire for the buss but bring it to a central point mount another fuse block and branch off to your buildings.

You have to consider is the wire the fuse is protecting big enough to handle the rating on the fuse that your using . If it's not and you use it anyway you've just made a nice heating element and if something shorts out a nice fire.

Thanks Dale

David
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quote:
unless you have had your KW rebuilt it has some time and wear on her, try not to stress the transformer to the max load.

Dave,

I acquired it a long, long time ago, probably in the early to mid 1970's, and as far as I know it is in its original state. I have used it very little myself, but I will make sure not to stress it.

Thanks for the advice..

Alex

Happy O-Gauge Railroading!

Alexander Müller

See My Mostly Completed Layout Here

OGR  forum member since 26 January 2008

()
Alex, Not hard to open the KW do a basic inspection. I have had to work on some ZW and KW that had been rode hard. Others hardly ever used. It is worth checking to ensure it has not been modifed, or internally damaged.

Look for terminals that are loose, or replaced with nut style vice rivet. Dull, or melted varnish, broken tabs on the aluminum frame, good insulation on the wires.

I think your principle is fine and you can keep it simple by just using the 2 variable outputs at 5 amps each.

Use smaller gauge (thicker wire) from the transformer to a buss. Than you can use larger gauge (thinner wire) to each accessory. If each accessory is wired individually, then that wire will only carry that load.

The fast blow fuse or a circuit breaker will protect your wiring and transformer (placed between buss and transformer).

I don't think it is necessary to fuse each accessory, unless you are going to string a number of them in series (which I don't recommend).

Remember a PH is 180W at 10 amps, so nothing is really abnormal here. G

MTH Authorized Service Center

Authorized ERR Dealer

Lionel Independent Repair Tech

Virginia Train Collectors Member

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Whenever you open up a "new to you" KW or ZW, you should check the rollers, they're one of the first items I check.

Nothing is so easy as the job you imagine someone else doing.

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quote:
Old KW & ZW transformers definitely need 10Amp breakers in front of them for any use on a DCS controlled layout.

What does the above quote mean? Where is "in front"?

And what breakers to buy?
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quote:
What does the above quote mean? Where is "in front"?

Generally, in "front" of a transformer means before the primary, and "behind" means after the secondary.

Arthur P. Bloom TCA 86-23906 "I love the smell of smoke pellets in the morning!"

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Sorry but none of this makes any sense.

What is a primary and what is a secondary?

When i look at the "front" of a KW, there are no wires, at the back, there are both 110 volts and smaller connection.

I do appreciate all the info here but wading through terminology is confusing.

Is there a wire diagram someplace?

Thanks!!
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Opticsguy,
Again I recommend purchasing Barrys DCS companion book Vol 2 and the OGR Video guide to DCS, they both explain how to set up your transformer for DCS running.
Simply put, you must have 10 Amp breakers or fuses between any ZW or KW transformer, and your DCS TIU, to safe guard your TIU. The old ZW & KW slow blowing circut breaker, will allow the old transformer to fry your TIU, if something goes wrong. Rich Melvin does a great job of explaining all this on the DCS Video Guide, both Barrys book and the OGR Video Guide will save you a lot of time, and money, both are well worth the money expened to purchase them.
I know we were also talking about the breakers use, in a slightly different way here in this thread, all this is understandable once you read and view the Video, it is not really complex at all.
The technical information in both these formats is just outstanding. Before you start building your DCS layout read and watch these two instructional
guides, they save a lot of time.
PCRR/Dave

Never worry about what other people think, be strong and walk in the way of the Lord.

()
Originally Posted by GGG:
Alex, Not hard to open the KW do a basic inspection. I have had to work on some ZW and KW that had been rode hard. Others hardly ever used. It is worth checking to ensure it has not been modifed, or internally damaged.

Look for terminals that are loose, or replaced with nut style vice rivet. Dull, or melted varnish, broken tabs on the aluminum frame, good insulation on the wires.

I think your principle is fine and you can keep it simple by just using the 2 variable outputs at 5 amps each.

Use smaller gauge (thicker wire) from the transformer to a buss. Than you can use larger gauge (thinner wire) to each accessory. If each accessory is wired individually, then that wire will only carry that load.

The fast blow fuse or a circuit breaker will protect your wiring and transformer (placed between buss and transformer).

I don't think it is necessary to fuse each accessory, unless you are going to string a number of them in series (which I don't recommend).

Remember a PH is 180W at 10 amps, so nothing is really abnormal here. G

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Originally Posted by GGG:  Hi,  Have you replaced the binding post before?  What the best way to remove the old binding post from the KW Transformer?
Alex, Not hard to open the KW do a basic inspection. I have had to work on some ZW and KW that had been rode hard. Others hardly ever used. It is worth checking to ensure it has not been modifed, or internally damaged.

Look for terminals that are loose, or replaced with nut style vice rivet. Dull, or melted varnish, broken tabs on the aluminum frame, good insulation on the wires.

I think your principle is fine and you can keep it simple by just using the 2 variable outputs at 5 amps each.

Use smaller gauge (thicker wire) from the transformer to a buss. Than you can use larger gauge (thinner wire) to each accessory. If each accessory is wired individually, then that wire will only carry that load.

The fast blow fuse or a circuit breaker will protect your wiring and transformer (placed between buss and transformer).

I don't think it is necessary to fuse each accessory, unless you are going to string a number of them in series (which I don't recommend).

Remember a PH is 180W at 10 amps, so nothing is really abnormal here. G

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Here's a link to Olsen's. Also a good place you can order parts.

franktrain

franktrain

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For a copper conductor the amp capacity of a conductor is based on the wire size, insulation type and number of wires in a bundle.  For wires down to 14, the capacity information is available in the NEC. What do you use for amp capacity for conductors smaller than 14?

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Dale thanks for the reference.  It appears that a 10 amp circuit breaker is appropriate down to 22 gauge wire as long as it is at least class B insulation.

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Remember that the ampacity isn't the whole story.  There is also a table of voltage drop per amp per foot that may indicate that a wire run is too long for the amount of current and allowable voltage drop, especially when you are starting out with only 12 or 18 volts.  A similar table for house wiring may allow a 5% drop for a run, but at 120 volts that is a 6 volt drop.  That amount of drop would be disastrous on a train layout!!

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Note to Alex:

I have purchased a number of 5 ampere circuit breakers that I use for all my circuit power. I insert 1 breaker between my KW  ouitput (I have 4 units)) and my TIU (I have 2).  I also insert another circuit breaker between each TIU output and the wiring to the track. I also have a circuit breaker and fuses for power to all my MTH RealTrax tunouts since the turnouts are powered separately (not using track voltage).

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With 5 amp breakers I would guess you aren't running any dual-motor postwar diesels with lighted cars.

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All my engines have "can" motors.  All my passenger cars are being converted to "low power" LED lighting systems.   All my turnouts are externally powered by a separate KW supply.  I have multiple TIU outputs poweed by multiple KWs which will power different blocks.  Even if I run multiple engines in lashups on a single track I will not exceed 5 amps per KW.

I also have 10 amp circuit breakers which I can use.

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