zw and kw coils

The ZW & KW have one secondary coil. The individual handles control rollers that run across the winding making contact, thus creating a variable voltage. The available output wattage of a ZW or KW is about 75-80% of the input watts. thus, a zw has about 180w available. since you are using only one output, all 180 watts go to the TPC. It is possible to connect two lionel 135W or 180W transformers to the TPC input, but I would not try it using zw's or Kw's, as you cannot gaurantee that the inputs from each ZW are equal.

Hop this helps---

You can get 220 measured watts out of a ZW(R) for a fairly extended period, I ran it at that level for over an hour and the temperature rise wasn't sufficient to alarm me.  It did get warm, but certainly not hot.  The ZW (not the R) would be slightly less continuous, but I doubt it's as low as 180 watts.

I agree you can't really parallel these safely, you may have excessive current between them negating much or all of the additional power.

I think you would be amazed at how hot a PW ZW gets with extended use at even 160 or 170 watts.

Why not just get a Z-4000?

You can pull nameplate rating of 400 watts all day, and the fan keeps it cool.

Just my opinion.

Rod

This is one of those discussions that seems to pop up every now and then.

ZW 250's, ZW 275's and ZW 275 Type R's can all put a total of 180 Watts rms to the track out of 1 handle or added up over all 4 handles. 

KW's are 140 Watts rms output to the track total.

The ZW "250"or "275" are the rated input from the wall outlet.

You can read it in the original service manuals from Olsons right here below or look it up in the service manuals from Greenberg or Kline.

KW

http://pictures.olsenstoy.com/cd/transfmr/pskw1.pdf

ZW

http://pictures.olsenstoy.com/cd/transfmr/psvw1.pdf

Or here where some nutcase with nothing better to do tested them because he didn't believe it either.

http://www.tranz4mr.com/site/Z...._ZW_275_Type_R.html

The type R seems to have a little less heat rise for the same power output, at least for a sample of one.  I connected my ZW(R) four 8 ohm 75W resistors in parallel to give me a load of 2 ohms, then added a couple of auto headlight bulbs to get the measured current up to 10 amps at full throttle.  After all night running that way, the actual temperature rise inside the case measured with a thermocouple was 22C, still a long ways from any damage.  The measure RMS voltage out from the output was 15.9, the ammeter reading was right at 10.2 amps.  That was 162 watts, but it was all the constant loads I had handy.

The limiting factor for the output of a ZW

is the 14 amp circuit breaker not watts.There is

no way for the ZW to measure watts.If your load

on the 4 outpus of the ZW is equal to 3.5 amps per output,

you will get more power output and less power loss inside

the ZW than if yoty draw the full 14 amps from a single output.

I'm afraid I don't understand your logic of not measuring output watts.  I have a true RMS meter and a resistive load, so I should be getting pretty close to the actual wattage.  I agree that equal power distribution on the outputs is probably better, that way less current is going through each roller, which is a high-resistance circuit.

The ZW is just a dumb box with only a 14 amp circuit breaker

to limit the the output current. The ZW cannot shift output

from one output terminal to another terminal. The ZW cannot

measure power only current.

The output from the ZW is a sine wave and with a resistor

load, a plain multimeter should give voltage and current readings

when multiplyed together should give a corrent power

output valve.

The newer ZW does not give a sine wave output so a true RMS

meter is required to give a correct voltage or current reading.

That is why Lionel made 2 different volt/amp meters

one for the sine wave voltage from the old ZW and a different

meter to measure the shark fin signal from the new ZW.

All true pa, however the point about equal distribution of the loads does make sense, just to equalize the current flowing through the respective rollers.  Other than that, I agree 100%.

Let R be the resistance of the roller , wiring to the terminals,

output terminal.Power drop is I Sq R. so if all 14 amps come from

a single terminal, the power loss is 14 *14 * R or 196 R. If only 3.5 amps comes from each of the 4 terminals,then total power loss is 4*3.5*3.5 * R or 49R.

Drawing the full 14 amps from a single terminal will result in 4 times the power loss

 than if only 3.5 amps is drawn from each of the 4 terminals.

Correct PA, I was agreeing with that part.

Hi Taylorra, To put it simple, your friend is mistaken.  The postwar ZW has only 1 big coil with throttles. Each throttle has the potental for the full power. If you use only 1 throttle you get full power to it. If you use 2 throttles (or more) then the throttles will have to share that full power. The full power can be used on one or more throttles until the circuit breaker goes open.

   For example suppose you use just 2 throttles. Divided by 2 that would seem... to be rounded to 135w per throttle. But it's not like that. On the left throttle you could run a gigantic train triple headed with 3 locos using 220w. On the right throttle you could run a little 2026 steamer off of 50w. That is what is great about the old ZW. Of course using full power like that the transformer would soon overheat, but you get the picture.

    A KW is built very differently but the 2 throttles work the same as how the ZW does. The difference here becomes the accessory windings are fixed, not adjustable. But accessory power still has to be shared with throttle power.

   None of this takes into account the whistle controller windings. Watt rating of old transformers is how much power it could take from the wall, not how much it puts out, but there is usally a strong correlation between them.

    Very best, Don Johnson