Lionel PH 180 voltage

1) Check the voltage with a known good meter.
2)Check the line voltage and see if it is proportionately higher.
3)It really won't make any difference regardless.

My line voltage is 126 VAC measured with a Fluke true-RMS meter.

Unloaded, a PH180 measures 18.95 volts, with a 8 ohm resistor, slightly more than a 2A load, it's 18.62 volts.

The date code of the transformer I tested was 2006 12

My PH-180s read just a little bit less than GRJ's, but still somewhere in the 18 and a few tenths range (18.4-18.6 or so). I don't remember exactly what it was, but that's pretty close. However, I have never checked my house power at the outlet feeding the PH-180s. I'm sure GRJ's testing methods are probably a little more thorough with more accurate results than mine as well, but at least I was using a TRMS meter (although it is a low end one and not a Fluke).

Does anyone know how accurate the PS3 engine's voltage readings are? Probably close, but could there is a slight margin of error introduced there?

Thank you GRJ and Rob!  My track had very little load, just the engine and a few track sections.  So, 19v measured through the engine isn't too far out of spec.  I will need to get a good meter someday. Does make me curious about my line voltage.  

George

A "fixed" voltage Powerhouse transformer will actually have a somewhat variable output voltage.  This depends on the resistance of the windings, altho this resistance is somewhat difficult to measure, being so small (including the fixed wires to the special connector).  The voltage drop is dependent on the output current flowing thru this resistance.

There is also the issue of the smaller house current flowing thru the primary coil... not to mention the magnetizing current also taken  from the house line.  The first is a bit significant; the second not so much so and usually ignored,

The so-called "short-circuit test" is typically used to directly add up most of the factors and is considered sufficiently accurate for field use.  With the the 135-watt PH (rated 7 amps), I obtained a value of 77 amps.  This indicates a regulation of nine percent  (7/77) or one part in 11.  This means that in the vicinity of 20 volts no-load voltage, the full-load voltage will be about 2 volts less (20/11) or 18 volts.  The half load voltage will then be 19 volts.

I assumed at the time that the design of the 10-amp PH (180 watts) would result in these same output voltages from no-load to full-load.  So the observed reading of 19 volts is not to be unexpected, with a locomotive draw approaching 4 or 5 amp, depending on added resistance of added wiring, track, and roller pick-up.

So I'd say the indicated 18-volt output is at the rated output of 10 amps for the 180-watt  PH.  I can't recall if I made a winding ratio test to verify this, but I do recall checking the line voltage. as all of the outputs increase as line goes above 120v.

Note:  It is possible the PH's were designed for the 125v 60Hz Mexican system (also said (Internet) to still be in use in parts of California) as had been the case with the postwar ZW.  The need here would be for a proportionate increase in iron core weight.  A little more weight would cover use on 50-cycle current in Europe (60/50)...  I've noticed the 10A PH's are rather on the heavy side, altho reaching 110v @ 50cyc is only little further than Mexico.  There is some copper penalty as well, of course, possibly equal to the added iron weight.

--Frank

GRJ-- If you normalize your results to 120v (ie, minus 5%), you'd have about 18 volts, no load, very closely.  The full-load drop would be about 5 times your voltage drop (5x0.33v) which is pushing a 2-volt drop no-load to full load.  Interesting.  Suggests 18v rating may be no-load.

I too use my old professional tools-- which was mainly a clamp-on ammeter, digital, with 5-200-600 settings, amps ac or volts.  Possibly not ideal for model trains .  The 5 setting was for the standard 5-amp current coils altho usually you had to wrestle with the cables.  1200-amps was usually on two cables.  I'd have to dig it out to get the name.  --Frank

125v 60Hz Mexican system

Frank, what's the difference between that and what DomVaPwr feeds us here?

What do you recommend for a TRMS meter for more casual use?  I am looking at a Tekpower TP5000 or an Extech 205T.

George

George, either of those are fine, we're talking model trains, not the Space Shuttle!

Frank, I tested three other PH180's, they tracked that one very closely, within about 1/10 volt with and without the load.  I've learned more than I needed to know, so I'm done.

GRJ--Well, I'm not going to go test a 10A PH even though I now know the test won't damage the electronic control of its disconnect relay (since Cam's drawings resurfaced).  I'm a little surprised the regulation has been reduced a bit (thus the available short circuit current raised a bit more than proportional to the 7A PH).  But I'm fine with your voltages.  It's interesting that mass-produced small transformers seem to be more consistent than their larger cousins.

RJR--Dominion looks for a nominal 120v, but after an AC compressor motor failure (it wasn't, it was the Cap start), I asked for a voltage check at the house.  At 10 am, weekday, the lineman measured 122v at the meter.  He said we were lucky to have only 8 houses on the local pad mount transformer, as now (then about 15 years after our house had been built in 1983 in the VA Power era)  Dominion was connecting 16 houses to the same size of pad mount.  So I was able to calibrate my mirror scale voltmeter (1%) to his anyway.

 Our  pad mount is unmarked, but it looks to be about 100 kva and  I'd guess about 2-1/2% impedance from the length of runs and the 10,000 AICS panel breakers.  So that is about 400 amps nominal for us; each of the eight houses would have had 200 amp services except possibly two built earlier during the gas moritorium.  Of course, the pads are run at overload part of the day.  We are about 3 miles from the substation, first at 35kv and last half mile UG at 12kv.   Dominion sheds load only to 5% low, rolling blackouts after that.   We have a lot of  short blackouts  cleared (trees?) by the automatic reclosers  of recent years.  UPS on the router has helped.  --Frank  (EDIT to correct 100 kva pad mount as being 400 amps; verified this as adequate for an expected panel loading  of 20 kva, 61% of that in a group of eight homes (summer electric air conditioning).  In fact, it's right at the rating.  Often only the primary is fused, generally at twice the rating.  Maybe that is where the change to 16 homes came from.  That's absolutely to be ROFLOL    (The overload limit is 140% or double the heating... the twice-rating fuse on primary side is to prevent the magnetizing inrush current on a cold start from blowing the fuse.  The only thing on the secondary side that this fuse can protect against is a short in a service cable.) FJM

Ironically, I just tested my two mains today, each of which is powered by a separate PH 180 brick. Each main had only a locomotive on it - diesels from MTH in both cases. Both mains registered at 18.89v. 

PJB posted:

Ironically, I just tested my two mains today, each of which is powered by a separate PH 180 brick. Each main had only a locomotive on it - diesels from MTH in both cases. Both mains registered at 18.89v. 

Can you check what the engine says the voltage is?  I am going to do this once I get a better volt meter.

George

Frank,

Thank you for your posts on this thread. I am learning and trying to follow. It's helpful to me to understand how the power from the supplier and system impact my trains. 

George

I have a dedicated 50KVA powerline transformer that just serves our house.  We also have 400A service here, three heat pumps.  Probably why my powerline voltage is a bit higher than normal.

George S posted:

What do you recommend for a TRMS meter for more casual use?  I am looking at a Tekpower TP5000 or an Extech 205T.

George

I have the Extech 205T, got it from one of the closing Radio Shack stores here for like 60%-70% off. Couldn't resist the price. It's ok, but pretty basic. I looked at the Tekpower you listed to compare and it appears to have the dynamic bar graph below the measurement readout. I think it would really be a nice feature to have. It also appears to have a few more features than the Exech. Might just have to try one of those myself, looks pretty good from here and the price is very good too, IMO.

I received my Extech 205T True RMS meter and tested a few things.  My line voltage is 124.5V.  However, my PH180's read higher voltage than GRJ with no load.  On a 2000 49 model, I read 19.48V with no load.  On a new 2014 09 model, I read 19.62V with no load.  As Rob suggested, I won't worry about it, but at least I can double check readings now.  

P.S. I phase corrected the 2000 49 model internally by swapping the output pair of wires.

Somebody's meter is not telling the truth.   I do get virtually the same readings with two different true-RMS meters, so I have a fair degree of confidence that my readings are reasonably accurate.

Don't you need a load on the transformer to test properly?

Ken M

You should have a light load at least, even a 1k resistor is enough.  That swamps out the stray capacitance coupling that results in erroneous AC readings.

My modular club has 2 180 bricks on each of our four mainlines. Today  I was running 3 powered engines with a sizeable train. My voltage dropped from 17 volts to 12 according the volt meter we have on the track. A few weeks ago I ran on a different track and the and it did the same. It actually dropped to 10 volts. The 4 180 watt bricks on the two mainlines I experienced this are about 10 years. Is the voltage drop a sign the bricks are failing? The other 2 mainlines have newer bricks but I haven't had a chance to test them with a big train yet.

@Texas Eagle 77 posted:

My modular club has 2 180 bricks on each of our four mainlines. Today  I was running 3 powered engines with a sizeable train. My voltage dropped from 17 volts to 12 according the volt meter we have on the track. A few weeks ago I ran on a different track and the and it did the same. It actually dropped to 10 volts. The 4 180 watt bricks on the two mainlines I experienced this are about 10 years. Is the voltage drop a sign the bricks are failing? The other 2 mainlines have newer bricks but I haven't had a chance to test them with a big train yet.

This question depends on many factors. How large is the layout/were are the engines in the layout when the reading is taken/track connection condition

What guage is the layout wiring. Lionel recommends at least 14ga wire when connecting a 180w brick to the track.

The layout this weekend is 25 x 45. We have a bus cable that supplies power to every module. The voltage drop is constant throughout the layout but it does vary as the train is moving.

@Texas Eagle 77 posted:

Is the voltage drop a sign the bricks are failing? The other 2 mainlines have newer bricks but I haven't had a chance to test them with a big train yet.

IMO, multiple bricks aren't failing, that's an almost never heard of scenario.  You have some connection issues somewhere in the track feeds.  Put a 3-4 amp load on the track somewhere and look for voltage drops on every connection of the power feed to the track.  My guess is you'll find it.