Measuring track voltage

I think the voltage reading is based on a top end of around 20 volts. So if the top value is less, the other readings will correspondingly be lower. Barry explains it a whole lot better in his book.

Very good I will look in the book.  I'm sure resistance has something to do with it.

Mr Union Pacific posted:

With my track voltage set to 18 volts using my z4000 I decided to measure the track voltage with my new GP38-2 in Family Lines livery.  It measured 15.6 to 16.4 all the way around my inside loop.  Is this normal?  My trains run fine.  I was just under the assumption that it would be close to 18 volts.  

I recently purchased a Z4000 and noticed the same. Voltage output on the transformer meter is not what's at the track.  My guess is after resistance of the wires and track it drops a bit.  Either that or a peak vs true output difference between what the readout says and actual track voltage.

One needs a meter capable of reading AC voltages in True RMS, if you are looking for the actual voltage.

Secondly, modern AC transformers need a load to read or set an accurate measurement due to internal electronic controls. This can be accomplished by placing an incandescent light bulb (18v rated) across the transformer outputs or the track rails. Some use a resistor, but I don't recall the rating. The bulb is a resistor.

The current draw of the engine is causing the voltage drop on the meter. There is not enough resistance in wiring and track unless something is wrong.

Compare the amp readout at 18v no engine and with the engine again.

Setting the handle at 18v is setting the maximum voltage limit. Not the amperage.

If it is an MTH engine, push the handle to full and check the readouts with the engine running. Lionel command engines shouldn't get more than 18 volts. They aren't designed for it.

it's about the Watts that an engine needs to run smoothly. That's the power or energy to run it. So, the GP38-2 apparently gets enough amps at 15.6 to 16.4 volts to run nicely.

Multiply the 16.4 x the amperage readout to get the Watts that the engine is consuming. Subtract that from the Z-4000 maximum Watt rating and the result is the amount that the transformer has in reserve.

My explanation was about reading track voltage with the remote. Sorry if I misunderstood. Carl has it nailed when reading at the track itself.