MTH Z4000 Waveform Pic

John

It is a pure sine wave on the whole throttle range?

Dale H

Yep, looks very similar to that, it was close enough that I decided one picture would do it.

Except for the zero crossing points, that waveform looks better than my AC from the power company.

grj;

Thanks for posting that.

I had always assumed it must be close to a pure sine wave. Nice to see, especially at a pretty good load.

Rod

By popular demand, I'm posting some shots at medium, and high voltage with no load, then again with a 2 ohm load at low, medium, and high throttle.  At full throttle that gets me around 8.5 amps from the transformer.

There was a shot at low voltage unloaded, but for some reason I captured a blank screen, and I don't feel like doing it again.

As you can see, unloaded there is a bit more distortion in the waveform than when it's under load.  However, in all cases it appears that it's probably close enough to a sine wave to not cause issues with devices that expect a pure sine wave.

We'll call it a semi-pure sine wave.

Waveform at 11 VAC and no load.

Waveform at 21 VAC and no load.

Waveform at 4.9 VAC and 2 ohm resistive load.

Waveform at 12 VAC and 2 ohm resistive load.

Waveform at 19 VAC and 2 ohm resistive load.

just curious (since I'm not too electrically in tune), but why would anyone care about what kind of sine wave is produced with NO LOAD?

Again, just curiousity asking

thanks - walt

It was just an observation of what I saw before I switched on the load.  Since the waveform was slightly different, I figured I'd include it. It's not much different, but you do see a slightly cleaner waveform under load. 

If this were a real function test, I'd have also included different loadings and the waveforms to match.  However, I didn't want to spend that much time doing it.

Note that synthesizing a sine wave is considerably more difficult than the simple chopped waveform control that most electronic transformers perform.  Given that this is done at high power, it's pretty nice.  I've built similar circuits in the past that generated a near perfect sine wave at much lower power for driving aircraft panel instruments.  Of course, I had to do tricky things like vary the phase in relation to a reference, so it was a non-trivial task as well.

Looks better than the wall power here John !

Our wall power flat tops badly here - Overloaded/Saturated  Transformers feeding the lines.  I've seen the RMS drop to 89VAC....

Good for testing, Bad for operations.

89 volts!!!  Yikes!  I have the opposite problem, I see 127-130 volts most of the time here.  I have a dedicated transformer that only feeds my house, so the AC waveform looks just fine.

John thanks for showing us the results and I knew their was a season that I like my two Z4000. Thanks Again.

I've only had it for a couple of days, but it is an impressive transformer.  I've used them at other locations, and they certainly get good reviews.

Can't go wrong with a Z-4000 IMO; ZW-L notwithstanding.

Z-4000's are pretty much all I use for track power these days.

They are also pretty difficult to damage.

Rod

That's because the TIU's die first !

Chris, that was harsh!

I actually like to power my TIU with the Lionel PH180 bricks.  It has a lightning fast electronic breaker that responds before any mechanical or thermal breaker will.

John - Did you do your testing with the typical wire wound power resistor or a non-inductive power resistor?

Well, I don't have a non-inductive resistor of that power rating, so I'm sure these are wirewound.  However, I doubt they contribute significantly to any waveform distortion, the inductance of them has to be pretty small.