Amperage - Some measurements from Ruritanian Railways

[whatlep]

Over the past few days, I've been tidying up the layout's wiring and creating a neater "desk" for my LGB MTS power supply, with the option to include an MTS booster. Before plunging in, it occurred to me that it would be a good idea to find out just how many amps I'm typically using. I also thought the results might be handy for others.

If you don't want to read the details, here are the key points for me from the tests:
1) Base load for DCC (i.e. before any trains are moving) may be significant if you have several ancillary modules attached.
2) Running unrealistically quickly or on steep gradients (like my 1 in 20/ 5%) uses a lot of amps. Running slowly looks better and may save you the cost of a big transformer or booster!
3) Unless you are running more than 6 LGB motors simultaneously, chances are you don't need a booster. If your other demands (lights, point modules etc) and your trains' speeds are low, 8 motors may just be possible, though it's pushing things.

To test, I attached my trusty multimeter between 50110 transformer and 55006p central station, thereby getting a measure of AC demanded of the transformer, not the DCC signal.

Here are the results (all shown in amps), measured today until rain stopped play:

Track disconnected, 55006p attached - 0.175
Track connected - 0.4

The 400 milliamp figure is my layout's "baseline", showing the inherent current consumption of the MTS central station (175 millliamps), plus two Massoth reversing loop units and 3 Massoth point/ switch modules (225 milliamps over 5 units).

Now to [STRIKE]play with[/STRIKE] test some locos....

LGB Mallet (2 motors)
stationary, lights off - 0.45 (DCC chip consuming 50 milliamps at idle?)
stationary, lights on - 0.54 (3 lights each taking 30 milliamps)
moving, MTS setting 6 (of 14), lights on - 0.6-0.9 amps (varying with gradients)
moving, MTS setting 12 of 14, lights on - 0.9-1.5 amps

2 * LGB 2095 diesels (4 motors)
stationary, lights off - 0.46 (2 DCC chips consuming 60 milliamps total at idle?)
stationary, lights on - 0.56 (3 lights each taking 33 milliamps)
moving, MTS setting 6 (of 14), lights on - 1.45-1.98 amps (varying with gradients)
moving, MTS setting 12 of 14, lights on - 2.6-3.7 amps

I also did some tests with the Mallet hauling seven LGB 2-axle hoppers, but the current draw was not significantly different. I suspect that tying 6 heavy coaches on the 2095s would increase the current draw, but need a drier day to test that theory!

Finally, switching points via a DCC module causes a severe, albeit momentary load on the transformer. Switching one point took typically 900 milliamps: switching two at the same time about 1400. Whether this momentary load would casue the transformer to trip out due to overload I haven't been able to test - yet!

 

[stockers]

Looks like the motors on your whizz cranks may have seen better days!:thumbdown:

 

[whatlep]

Looks like the motors on your whizz cranks may have seen better days!:thumbdown:

Yes, I suspect they're on the high side, though remember that the amps shown include all the ancillaries too. The 4 motors are drawing between 1.43-3.14 across all 4 of them when running uphill. They seem to run OK for extended periods, so not too worried just yet....

 

[stockers]

No, I would not worry too soon. My Mallet flat out pops the overload on the chip (3 amp) but run below speed 10 of 14 it is fine. Funny though - once its been running for a few minutes you can run it at 14 no problem.
It is quite surprising how much more current these locos pull at higher speeds. Slowly the twin motors pull 0.3 amp or so - speed up and that goes well over an amp.

 

[Gizzy]

You've obviously got an AMPle Power Supply Peter....

(Exits, stage left, to boos and hisses!)

 

[whatlep]

As an additional note Peter, an MTS II set will give out more amps (Mine does)
I have run 11 LGB motors of it plus 4 lit bogie coaches and it has never cut out or overheated.

Interesting Paul. Utimately the transformer must determine how many amps are available, but I wonder if the 55005 is more elegant in terms of its circuitry and/or has less internal overheads as it's only supplying one bus type, rather than 2 in the 55006?

 

[stockers]

As an additional note Peter, an MTS II set will give out more amps (Mine does)
I have run 11 LGB motors of it plus 4 lit bogie coaches and it has never cut out or overheated.

Interesting Paul. Utimately the transformer must determine how many amps are available, but I wonder if the 55005 is more elegant in terms of its circuitry and/or has less internal overheads as it's only supplying one bus type, rather than 2 in the 55006?

Or the overload cutout is just a bit quicker!

 

[whatlep]

A brief postscript. Managed some more testing today with 2 * 2095 diesels and 6 LGB 307x series coaches. A hefty load, bearing in mind my 1 in 20 gradient.

Amperage at MTS setting 12 (of 14) varied from 1.43-4.6 amps (downhill/ uphill), so at worst, each motor was drawing almost exactly 1 amp. Well within the Massoth XL chip's rating and normally I would run at setting 9, but still a bit close to maximum quoted output for comfort.

With a little experimentation on point switching, I had instantaneous peaks of 5.72 amps shown as the pulses were sent out to MTS controlled crossovers. Clearly the LGB 50110 can tolerate this, but as a result of the testing I will probably add a 55090 booster to give a bit more amp "headroom".

Most impressively to me, the 50110 transformer was rock solid on output voltage. It never dropped below 17.9 volts, nor exceeded 18.05, whatever the amps consumed. Much better than some brands I've measured.