Lionel KW Transformer - Using Fixed 14v for 022 Switches

[cwburfle]

Sorry to repeat Rob's comment. I guess I skimmed some of the posts.

[ADCX Rob]

cwburfle

If you are using the KW just to power switches, why not use one of the variable voltage posts to get the best operation of your switches?

ADCX Rob

If this is a spare KW, just phase the two transformers with their U terminals as common and Use KW A or B for your switch power. In this fashion, you can fine-tune the voltage to the switches as needed.

[cwburfle]

If you are using the KW just to power switches, why not use one of the variable voltage posts to get the best operation of your switches?

[lionelsoni]

If you connect the KW (either C or U) to the ZW and from there to the track, and if the transformers are in phase, the return currents from both transformers add together in the single common wire to the track.  The worst-case current is 15 amperes for the ZW and 10 amperes for the KW, for a total of 25 amperes, which strictly speaking calls for 11 AWG wire.  You probably wouldn't find that and would have to resort to 10 AWG, which is safe for 30 amperes.

But, assuming a little diversity between the transformers' currents, a slight reduction from 11 to 12 AWG is probably reasonable.  Alternatively, you can wire both transformers separately to the track, with minimums of 14 AWG for the ZW and 16 AWG for the KW.  But, if the transformers are out of phase, then a single 14 AWG common will suffice.

[blhs12]

O.K.  Thanks Rob.  Appreciate the info. I have a better understanding now.

Ed

[ADCX Rob]

As long as the ZW is controlling the trains there is no issue. Phasing is recommended to keep the on-layout voltage potential(s) at 6-20 volts instead of 14-28 volts. 28 volts isn't too bad, but phasing is a good practice to keep up for safety - two Type Z or V transformers out of phase can produce potentials on the layout of 48-50 volts at 14-15 amps.

There are advantages in advanced common return layout wiring of having out of phase power supplies where very long wire runs or marginally sized wiring might cause voltage drops, but for most of our uses it's better safe than sorry.

[blhs12]

Thanks Rob. I thought that it might be possible but wanted to be certain.

Intended to use KW primarily for 022s.  If I did so using the above arrangement, that  is terminal "D" for fixed voltage plugs and connecting "C" terminal of KW to"U" on ZW would it still be necessary to phase the two transformers so that I could run trains on the loop containing the switches? Just wanted to make sure I understand your recommendation.  Thanks,

Ed

[ADCX Rob]

You are VERY close... The anwer is yes, you can do this, but there is one(and a half) extra step... connect the D terminal to the fixed voltage plugs of your 022 switches and connect the C terminal of the KW to the U terminal of the ZW to complete the return.

The half-step is with regard to phasing the two transformers - orient the AC wall plug of the KW so when the ZW A control is set at 14 volts a bulb connected between ZW A and KW D is off or very dim, and then gets brighter as you lower A toward off.

This will limit the versatility of the KW for other uses on the layout, as all output voltages will now be referenced to KW C and ZW U as common ground.

If this is a spare KW, just phase the two transformers with their U terminals as common and Use KW A or B for your switch power. In this fashion, you can fine-tune the voltage to the switches as needed.

[blhs12]

Here's a different questsion regarding using KW Tranformer terminal D (fixed 14v) for 022 switches.

Can I safely connect the D terminal to fixed voltage plugs of my 022 switches and use the U terminal on my ZW as a ground.  ZW provides power to track.  Would I have to phase the two transformers.  Granted I could run the 022's off the ZW but I am curious if the above procedure would work.  Thanks.