10 amp breakers

JohnGaltLine posted:

PLCProf, 

You're probably right that the meter is adding resistance, but I don't know that it is going to be enough to matter when addressing how much current the transformer is going to deliver with a short.  From a scientific stand point, there is a huge difference between our results, but from a practical stand point we both have the same results,  A fuse is needed if you want to avoid the chance of melting your layout and starting a fire.  

As I think about the issue it does make some sense that this is the result of the test.  The brick puts out 100 watts (or so).  What does it care if it is 5 amps at 20VAC,  or 20 amps at 5 VAC?  I'm sure that's not the correct math, but it seems to line up well enough.  

After doing the test, it seems my reply was garbage.  With an alligator clip from hot on the barrel jack to hot on the accessory post I saw over 50 amps on the clamp meter before burning my fingers and melting the alligator clip's insulation.  

Net result is still, if you want to avoid burning your house down, put a fuse on the hots.  

JGL

Very good. 

FWIW, ADCX ROB's comments on the current between circuits of the ZW are probably correct, but I haven't done any measurements. The difference is, the ZW uses carbon rollers specifically to limit the short-circuit current when the wiper is resting simultaneously on 2 adjacent turns of the secondary winding. But, the resistance of the carbon roller is also included in the load circuit! In the case of a circuit-to-circuit fault, you now have two carbon rollers limiting the current flow, one on each handle. Plus, intentionally, necessarily, or otherwise, the magnetic circuit of the ZW provides a lot of current limiting; the loose lamination structure on the original version, plus the non-interleaved structure of the "R" version provide less-than-perfect coupling and high leakage reactance. In both versions the magnetic circuit is long. The transformer in the Z-1000 brick, on the other hand, looks like a standard industrial design intended to minimize those factors.

JGL, the price difference between 14 & 16 gauge is minimal.  I have some runs pushing over 30 feet.  My experience running trains is that voltage drop is always a problem, whicih an operator may or may not recognize.  Also, I have found that too thin a wire, on a circuit carrying a good load, seems to reduce the DCS signal.  I'm sure there will be disagreements on this, but it's my railroad, and probably my last, so when building it 25 years ago I drew on my experience dating from the 40's to make sure all ran well.

PLCProf posted:

... the ZW uses carbon rollers specifically to limit the short-circuit current when the wiper is resting simultaneously on 2 adjacent turns...

Good point, I did use the rollers in the circuit. This was on a 1948-49 version ZW.

And, make no mistake, by the time the voltage setting got to 6 volts difference, the needle was jumping off the scale at well over 20 amps.

I will try it again when I get a chance using taps right off the secondary, bypassing the rollers.

It seems now that an inexpensive 6 amp breaker on each hot leg of a Z-1000 would be a good idea.

1. Lee F. (or anyone)- What is a TVS unit? Purpose?

2. Since I have 16 ga wire as all my power feeds, do I need to rewire with  #14 for my DCS?

3. I have "homerun" wiring (individual feeds to terminal strip at ZW) to various points but I did not insulate the track into blocks; could that affect my signal?

4. I have a 2023 UP that does everything but move; any suggestions? (I know this is a "traditional" question but you guys are good!)

Wally

Wally,

1. A TVS is a device that connects between hot and ground.  If there is a high voltage surge, it makes a connection to bleed (short) off the surge, protecting components on the line..  If the high voltage were prolonged, I'm sure it would break.

2.  If layout is built (in your profile, it is a good sized layout), I wouldn't go back and re-wire, unless you find problems out at the far reaches.  For any furthe track wiring, I'd go to 14-gauge stranded.

3. I would point out that if you are operating old conventional locos, you can get a lot of flexibility by severing the layout into blocks and putting toggle switches on each block's feed.  You are quite possibly affecting the DCS signal with multiple feeds.

4. You have to give a model number for the UP and describe the symptoms.

RJR:  UP 2023 A-A, silver (1952?); wiring seems all O.K. except for uncoupler pickup pad; headlight works; E-unit lever rises and "hook" seems to rotate the barrel; dry-cleaned the barrell surfaces a bit; a "hum/buzz" but armature does not rotate; I want to next check current flow through the various parts to see if something is not powering up. Have not taken E-unit out of mounting. Used Lionel diagram to help identify connections.

Wally

It's been almost 45 years since I last worked on an e-unit, so I've forgotten most of what I knew.  Be sure that there's no gum buildup on the solenoid plunger.  Lionel said it should not be oiled.  I'll defer to others on trouble-shooting.