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Current draw

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  • Member since
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Posted by CSX Robert on Monday, March 7, 2022 10:35 AM

gregc
i believe most modelers don't have panel meters, they're just not necessary until there's a problem.

True, they are not necessary, and I don't think anybody has said they are, they can be quite handy though.

gregc
i don't know what an RRampMeter can do that a good digital meter can't

If by "good" you mean a true-RMS meter, than nothing, but I would be willing to bet most model railroaders don't have a true-RMS meter lying around.  If it's not a true-rms square meter, then it won't give you the true voltrage or current of the DCC signal.  Do you need an accurate measure of voltage or current?  Most times not, but it can be useful information, and if you're measuring it anyway, why no get it right?

Even if you have a true-RMS meter, a purpose built tool can be a lot more convenient.

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Posted by CSX Robert on Monday, March 7, 2022 10:20 AM

Lastspikemike
Nobody so far has explained what one would need to use the current consumed information for. I've asked.

Lastspikemike
If you know your locomotives each draw less than 1 amp then by all means use that lower number to estimate the maximum possible power you may need for any given power district (my DCC layout has just one).

And how are you goint to know what you're locomotives draw without the current consumed nformation?Bang Head

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Posted by tstage on Monday, March 7, 2022 10:07 AM

Lastspikemike
Nobody so far has explained what one would need to use the current consumed information for. I've asked.

Apparently you suffer for SRS (selective reading syndrome).  I and several others have given you some examples where the ability to read current draw was helpful in diagnosing an issue with one's track or locomotive.

In my case, the motor of my brass locomotive was running erratically.  It wasn't until I viewed the fluctuations in current (i.e. from 0.18A to 0.9A, with spikes as high as 1.7A) with the built-in ammeter of my NCE Power Cab that I realized the motor was bad and/or binding internally.

Could I have come to that same conclusion without reading the current draw of the motor?  Sure.  However, the ammeter gave me quantitative numbers to compare against what a properly-operating motor normally draws to help me realize that something wasn't right.  In another case I could see that there was a short with a decoder install.  The current draw was slightly above the trigger point of the circuit protection of the Power Cab but stayed on long enough to view the current draw.

Yep, a pretty handy device and feature to have but perhaps not as important to others...

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by hbgatsf on Monday, March 7, 2022 9:32 AM

Lastspikemike

Nobody so far has explained what one would need to use the current consumed information for. I've asked. 

hbgatsf
Lastspikemike

What do you do with the information?

Your system either runs the trains or it doesn't.

Most of the time everything runs fine.  Occasionally gremlins show up.  When that happens troubleshooting is needed and I see this as a tool to help.

Rick

Rick

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Posted by hbgatsf on Monday, March 7, 2022 8:51 AM

Rich, I saw your thread about testing your engine facility,  https://cs.trains.com/mrr/f/744/t/285033.aspx.

As I said in starting this thread I don't understand how this electrical stuff works under the hood.  Can you explain in simple langauge the need for the light bulb?

Rick

Rick

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Posted by richhotrain on Monday, March 7, 2022 8:05 AM

gregc

i believe most modelers don't have panel meters, they're just not necessary until there's a problem.

i believe the most common problem is voltage drop either due to a bad wire connector or rail joiner.   these can easily be diagnosed with a meter regardless of accuracy.   just the difference in measurements between different track points is needed.

on the other hand, a current meter can't be used as easily as a voltmeter.   but adding a set of bananna plugs and strap between them during normal use would make it easy to use a current meter.   such jumpers could easily be added for each power district

i don't know what an RRampMeter can do that a good digital meter can't

Well, greg, everything that you said preceding that last remark validates the usefulness of the RRampMeter. Mounted on a panel, you have a constant visual reference. While my RRampMeters are mounted on the cabinet shelves with velcro strips, you can easily install the RRampMeter inline and remove it to test along the layout as needed. 

My previous post was addressed to lastspikemike who, at least intially, didn't see a need for any type of meter. "Your system either runs the trains or it doesn't".

Rich

Alton Junction

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Posted by gregc on Monday, March 7, 2022 7:19 AM

i believe most modelers don't have panel meters, they're just not necessary until there's a problem.

i believe the most common problem is voltage drop either due to a bad wire connector or rail joiner.   these can easily be diagnosed with a meter regardless of accuracy.   just the difference in measurements between different track points is needed.

on the other hand, a current meter can't be used as easily as a voltmeter.   but adding a set of bananna plugs and strap between them during normal use would make it easy to use a current meter.   such jumpers could easily be added for each power district

i don't know what an RRampMeter can do that a good digital meter can't

876

greg - Philadelphia & Reading / Reading

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Posted by richhotrain on Monday, March 7, 2022 5:56 AM

Lastspikemike

What do you do with the information?

Your system either runs the trains or it doesn't.

If you have "too many" locomotives drawing power switch one off and resume operations.

You just assume that each locomotive will try to draw about an amp maximum times the number of locomotives and that number needs to be less than the amps number stamped somewhere on your existing system. That's all you really need to know.

The RRampMeter provides a constant view of voltage and current draw, providing the user with a way to measure voltage drop along the rails and excess current draw from locomotive motors.

Here is a good explanation of the RRampMeter from Tony's Trains Exchange.

https://tonystrains.com/download/df-rram-AppNotes.pdf

Or, you can do it your way, Spike. Your system either runs the trains or it doesn't.

Sorta like a car without a fuel gauge. Your put a 5-gallon can of gasoline in your trunk and drive your car until it stops in the middle of the highway. Then, you add the 5-gallon can of gas into your fuel tank and drive on until you reach the next gas station.

You just assume that your gas tank holds, say, 15 gallons of gas and that you get, say, 20 MPG. That's all you really need to know.

Alton Junction

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Posted by bagal on Sunday, March 6, 2022 11:54 PM

Lastspikemike

You just assume that each locomotive will try to draw about an amp maximum times the number of locomotives and that number needs to be less than the amps number stamped somewhere on your existing system. That's all you really need to know.

Some in our club reckoned that we needed a booster based on a similar rule. RRampmeter showed that we were well within the capacity of the system. 

bagal

 

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Posted by RR_Mel on Sunday, March 6, 2022 7:52 PM

I run dual mode on my layout, DC or DCC.  I bought a couple of cheapie digital panel meters of eBay (China) and tweaked an interface circuit so that both the voltage and current work for either mode.  Both readings are very close, within .2 volts for voltage and 6ma for current.

Both meters are mounted on my control panel and monitor the track power constantly in either mode.

My max load in either mode is less then 2 amps.  Both my DC and DCC controllers have a max current of 3½ amps and so far I haven’t had any problems but it's neat to monitor whats going on.
 


Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 in July, aging is definitely not for wimps.

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Posted by tstage on Sunday, March 6, 2022 5:10 PM

jjdamnit

Hello All,

wrench567
My NCE Power Cab has a built in amp meter. It comes in very handy at the workbench for checking the overall condition of locomotives.

This is indeed a handy feature.

However, the wireless NCE cab does not include this feature- -that I know of. Perhaps a quick email to the great folks at NCE will clarify this.

The NCE PH-Pro does not have the built-in ammeter; only the Power Cab does.  And, indeed, it is quite a handy feature, as I have used it numerous times to double-check the current draw of a locomotive after a decoder install.  With it I also discovered that I had a bad motor in a brass locomotive I had purchased.  Replaced it with a coreless motor and it now runs beautiuflly and draws only 0.02A at speed step 001.

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by jjdamnit on Sunday, March 6, 2022 4:49 PM

Hello All,

wrench567
My NCE Power Cab has a built in amp meter. It comes in very handy at the workbench for checking the overall condition of locomotives.

This is indeed a handy feature.

However, the wireless NCE cab does not include this feature- -that I know of. Perhaps a quick email to the great folks at NCE will clarify this.

I only have one PowerPro command station/booster but I would still like to be able to read the power draw from the single unit to the five (5) power districts downstream.

There is space on the facia of the L-girder bench work, next to the UTP, where I could install one of these meters.

Thank you for opening this thread and its accompanying thoughts and suggestions.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by CSX Robert on Sunday, March 6, 2022 4:35 PM

Lastspikemike
Your system either runs the trains or it doesn't.

Or it runs intermittently.  Or it runs for a while and overheats and shuts off.  These issues tend to creep up when you're running close to the maximum current draw.  The best way to determine that is to...measure the current draw.

Lastspikemike
If you have "too many" locomotives drawing power switch one off and resume operations.

You may be below the "too many" threshold and still have shutdowns if you have one or more that draw excessive current.  The best way to determine if that is the case is to...measure the current draw.

Lastspikemike
You just assume that each locomotive will try to draw about an amp maximum times the number of locomotives

Most modern locos draw way under an amp, so if you go that route and run many locos you're likely gonig to be spending a lot of money on excess capacity.

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Posted by selector on Sunday, March 6, 2022 3:31 PM

I am on my fourth layout, the largest yet by quite a bit of trackage, and I'm still running it with my original 16 year-old Super Empire Builder, same throttles, same command station, same power supply.  I don't even need the PSX-AR that I had to use for reversing my diagonal train turner on Layout #2.  To keep the yard manageable, I have it isolated through a tail light bulb, but everything else is shorts-managed by the DB150.  Simple, works like a hot damn.

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Posted by selector on Sunday, March 6, 2022 3:26 PM

doctorwayne

Ah, thank goodness for the simplicity of DC.

Wayne

 

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Posted by wrench567 on Sunday, March 6, 2022 2:36 PM

  My NCE Power Cab has a built in amp meter. It comes in very handy at the workbench for checking the overall condition of locomotives. Now that I started a roster with Decoder Pro I have added the amp draw on speed step 1 and wheels spinning on speed step 28. It's easy to put in the notes column for future reference. Some of my Brass have tuned open frame motors and I like to know if they are getting close to the decoders limits.

   Pete.

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Posted by gmpullman on Sunday, March 6, 2022 2:10 PM

Yes, DCC is extremely complicated. Its a wonder any of my trains run at all.

So, in regards to having a meter to monitor what's going on with the electrical "pulse" of my layout I much prefer to have the information available to me.

I have thermometers, both indoor and out, all around my house. I really dont have a need to know what the temperature is but, well, I do glance at them occasionally. Same with my speedometer. Pretty easy to see how fast the scenery is going by out the window but I still like to have an idea of the time/distance relation of the vehicle.

My situation is very similar to Richs' above.

I started out with one RRAmp meter in a case. The terminals were spaced for a standard dual banana plug. This made it nice to use these plugs on my test track so I could pop the meter in-line to measure current draw on a particular locomotive.

Then I bought a pair, without the case, to mount at the layout itself.

 Power_V-A-meters by Edmund, on Flickr

The screw terminals come packaged loose and I soldered them in since I wanted to have them for my particular wiring needs.

Here's a look at my rats nest, warts and all. I "temporarily" suspended the pair of meters because I wanted to try them out before deciding on a permanent mounting location. As others have a similar situation I'm using two boosters on the main portion of the layout and each meter is relegated to one booster. This helped me balance loads between booster districts.

 Power_Digitrax-meters by Edmund, on Flickr

Panel mounting won't be a problem but you'll have to cut rectangular holes for the readouts. I may use regular household "Leviton Decora" outlet covers to act as the panel face for my meters. Allowing for a film of tinted material over the readouts will help for viewing in a lighted room.

I still use the "portable" RRAmp meter in the housing. It is sometimes handy for using on the trackage itself. I use an automotive lamp as "ballast" because taking open-current voltage readings doesn't give me a true "picture" of how good the continuity is feeding a particular section of rail may be.

I do use several of those small LED DC meters for my auxiliary supplies. They're handy but I don't believe they will give a useful readout of DCC current conditions.

 IMG_6337_fix by Edmund, on Flickr

Now it's time to take my blood pressure. Glad I have a sphygmamonitor handy! Who needs meters...

Cheers, Ed

 

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Posted by doctorwayne on Sunday, March 6, 2022 1:22 PM

jjdamnit
To operate two (2) locomotives was akin to hearing cats.

I often operate two (or more) locomotives at the same time, but run only one train at a time, as I'm a lone operator. 
I have run more than a dozen locos at one time, though, mostly for entertaining my grandkids when they were young....I start with one, then add additional ones when they're not looking, and eventually, some will begin to catch the others and couple together.

I then start removing locos one at a time, again while they're not looking.

They're old enough now to run trains, and do so with great care...a lot more respectful than some adults I've seen on layout tours.

Wayne

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Posted by jjdamnit on Sunday, March 6, 2022 1:05 PM

Hello All,

doctorwayne
Ah, thank goodness for the simplicity of DC.

Getting completely Off Topic when I ran DC on my 4'X8' pike I had 16 power blocks; some as small as a single piece of 9-inch sectional track. 

It was controlled by two (2) cabs, an Atlas controller with four (4) selectors, along with 19 turnouts.

To operate two (2) locomotives was akin to hearing cats.

DCC simplified the operations of running multiple locomotives simultaneously, along with running consists and Distributed Power Units in longer trains.

I agree DC does have a place, but I didn't find it easier or simpler than DCC.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by gregc on Sunday, March 6, 2022 12:45 PM

Lastspikemike
For our DC layout we have puzzling power variations in some Blocks (locomotive speeds change).

have you compared the voltages between the bad and better blocks?

is the wiring/power source to those blocks different?   

is there some type of block detector in series with the blocks that have less voltage?

greg - Philadelphia & Reading / Reading

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Posted by tstage on Sunday, March 6, 2022 12:43 PM

doctorwayne
Ah, thank goodness for the simplicity of DC.

Wayne

Even though I like & use DCC, there's nothing wrong with DC, Wayne. Yes

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by jjdamnit on Sunday, March 6, 2022 12:39 PM

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by doctorwayne on Sunday, March 6, 2022 12:31 PM

Ah, thank goodness for the simplicity of DC.

Wayne

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Posted by mfm37 on Sunday, March 6, 2022 11:35 AM

hbgatsf

The case is removable. Tony's sells a kit to upgrade their panel mount RRampmeter to a portable. Yes it can be reversed but for the $35 price difference I would just buy a panel mount version.

richhotrain

Buy the RRampMeter! Yeah, there is an expense associated with it, but it is designed to measure voltage and amps (current draw) under DCC power. It is more accurate for this purpose than a multimeter that measures pure AC power.

I own three RRampMeters, one in-line for each booster, and one that is portable, permitting me to measure voltage and current draw under load.

The two in-line RRampMeters permit me to see voltage and amps at a glance and at all times while the layout is powered up.

Rich

OK.  You touched on the next question I had.  You have two that are panel mounted and one with the case?  Can you remove the case from that model and panel mount it?

Rick

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Posted by gregc on Sunday, March 6, 2022 9:45 AM

richhotrain
I started out with a single panel mounted RRampMeter. But, a few years later, I divided my layout into seven power districts and, in the process, added a second booster.

yes.  it makes sense to panel mount the rrampmeters to measure current from each booster.   could easily see what the trains are drawing and if locos are having problems

the club here in cumberland has a DPST knife switch on the output of each circuit breaker and AR connected to the track.   those knife switches make it easy to isolate problems and would make it easy to measure the current drawn by a particular loco/train

greg - Philadelphia & Reading / Reading

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Posted by hbgatsf on Sunday, March 6, 2022 9:44 AM

Lastspikemike

What do you do with the information?

Your system either runs the trains or it doesn't.

Most of the time everything runs fine.  Occasionally gremlins show up.  When that happens troubleshooting is needed and I see this as a tool to help.

Rick

Rick

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Posted by wrench567 on Sunday, March 6, 2022 8:59 AM

  My former club had amp meters on the legs of the booster power supplies. They had a 10 amp scale and worked very well. Panel mounted in the booster district. A short in a district would almost peg the needle until the booster tripped.

  Just another way of judging power consumption.

     Pete.

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Posted by richhotrain on Sunday, March 6, 2022 8:28 AM

So, Spike, your answer to the OP is to forget about the RRampMeter, a multimeter, or any other electronic device to measure voltage and/or amps?

Just assume that each locomotive will try to draw about an amp? That's all you really need to know? Just run trains and forget about the rest of it? ConfusedConfused

Alton Junction

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Posted by richhotrain on Sunday, March 6, 2022 8:14 AM

gregc

not sure of the value of having two rrampmeters panel mounted.   it makes sense to panel mount one to measure current.   it can be wired anywhere between the booster and track.

but i would think using a 2nd would be more useful if portable to measure voltage across the rails at various points on the layout, in particular, far from the booster and at the boundaries where power districts meet, and presumably under load

greg, I started out with a single panel mounted RRampMeter. But, a few years later, I divided my layout into seven power districts and, in the process, added a second booster. That second booster was not necessary, but it proved very useful. At that time, I added the second panel mounted RRampMeter to display the measurements controlled by the second booster as distinguished from the first booster.

Those two panel mounted RRampMeters are not easy to remove when I want to test voltage/amps on the layout, so I bought the third RRampMeter for portability.

Rich

Alton Junction

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Posted by gregc on Sunday, March 6, 2022 8:04 AM

not sure of the value of having two rrampmeters panel mounted.   it makes sense to panel mount one to measure current.   it can be wired anywhere between the booster and track.

but i would think using a 2nd would be more useful if portable to measure voltage across the rails at various points on the layout, in particular, far from the booster and at the boundaries where power districts meet, and presumably under load

a simple LED can indicate if there is track power

greg - Philadelphia & Reading / Reading

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