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RailPro => RailPro Discussion & Help => Topic started by: atsfguy on August 24, 2019, 06:45:19 PM

Title: Motor over peak current
Post by: atsfguy on August 24, 2019, 06:45:19 PM
 After conducting the Full Motor Current test and measuring 610 mah, I had a caution icon appear on my screen indicating my motor had checked as “motor over peak current”.
  I checked Ring’s website hoping to find an error message explanation but did not. Is it drawing too much current?
  I have read of one locomotive belonging to a member drawing over 700 mah. What is the cut-off on current draw?
  BTW, this is on an Athearn blue box GP-7 that is about 35 years of age with few running hours.
  Thank you for your replies.
Title: Re: Motor over peak current
Post by: G8B4Life on August 25, 2019, 09:05:10 AM
Never seen anyone report that one appearing before, but the error message does exist. As for not finding anything about it on Ring's site, we'll just add it to the list of everything else that other manufacturers can publish about their systems but Ring can't.

My guess is that the motor tries to draw more than 2A at startup; ie it consumes 610mA running but to get it started takes more than the peak output of the LM, which is 2A. It may even report this at over 1A which is the continuous rating for an LM. This is all just speculation of course but I imagine that if the motor was drawing more than the Full Motor Current Test it would simply show Motor Overload and not Over Peak Current as the error message.

It might pay to give the motor and drive train a good going over if you haven't done so. I know Kevin has done a few installs with old Athearn motors so hopefully he might drop in with some hints for running RP with old Athearn motors.

I wonder if I could simulate my guess somehow, you've peaked my curiosity.

- Tim
Title: Re: Motor over peak current
Post by: William Brillinger on August 25, 2019, 09:35:42 AM
My first question would be: is your software up to date on the LM and the HC?
Title: Re: Motor over peak current
Post by: Alan on August 25, 2019, 11:05:47 AM
Current through a non-moving armature is determined solely by the resistance of its windings and the brushes. The current draw of a spinning motor is always less than that of a stationary armature because of BEMF. The current draw everyone sees on their HC is a spinning armature. A non-moving motor typically allows far more current to flow than an LM can handle however, because the motor starts spinning almost immediately, the LM doesn't shut down or report error. On a scope you can see the initial spike. Can't see it on a voltmeter because it is so brief. I have measured ultra-brief spikes in excess of 5 amps on an LM equipped Atlas HO loco.

I am guessing your GP-7 has a tight or binding drivetrain causing the motor to be hesitant to begin spinning. The LM can handle a very brief high amp spike. It can't handle a spike that lasts longer.
Title: Re: Motor over peak current
Post by: atsfguy on August 25, 2019, 11:15:09 AM
Alan, the me hanism moved very freely prior to placing the motor/ gear train in place.
Bill, in a telephone conversation a week ago with Tim Ring, he told me to update the LM after setting Full Motor Current. Why, I don’t know.
I will update the LM today and retry running.
Thanks for your help.
Title: Re: Motor over peak current
Post by: atsfguy on August 27, 2019, 04:55:20 PM
I discussed this issue with Tim Ring and he said the motor over current could  be from a short from the gray wire to the orange wire. I removed the motor from the loco and checked Kapton tape behind the motor, just for luck. After reassembling the engine, it ran OK. Found nothing to absolutely show why I was having problems with it. Now I need to lay more roadbed and track.
Thank you to all who replied.
Title: Re: Motor over peak current
Post by: Alan on August 27, 2019, 06:06:54 PM
Let sleeping dogs lie!  :D

Glad to hear its working for you.
Title: Re: Motor over peak current
Post by: Dean on September 11, 2019, 08:16:16 AM
The blue box motors draw a lot more current than the new can motors. I would check the gearboxes and maybe give them a lube job. If the engine hasn't been run much, it may loosen up after being run more.
One thing I do with all my engines is do a second motor full load test after they have been run for a few hours. Usually the current drops.
Title: Re: Motor over peak current
Post by: carrson on September 16, 2019, 09:41:07 AM
I also had the same warning icon appear "motor over current peak" just last week.. It is in an older 2004 genesis sd75 that has been running for over a year with no other issues. I tested the LM3s in another loco with no problems.. the drive line tested free and clear no binding..I ran only the motor on DC and had a little smoke puff out...Took the motor brushes out and one had broken at the tip that goes into the spring...replaced it with another brush (not quite the same size) cleaned the com and noticed that one com wire appeared to have a slightly darker colour than the others which i assume is the burn and reason for the smoke... reassembled the unit, updated the software and full motor load..it was inconsistent with starting... sometimes it would go other times it would not and the "motor over current peak" would appear... my thinking is the darker com wire is causing a dead spot on the com... so I'm going to replace the motor... 
Title: Re: Motor over peak current
Post by: llxlocomotives on September 27, 2019, 11:08:15 AM
What are you doing when this occurred?  My tests indicate Engine only flat surface high power current to be less than .4 Amps on the BB gold motor, the round jet motor would be close to the 0.7.  As you add train load(cars, grade etc.) this current draw will increase towards the stall current of the voltage.  I have measured the 100% voltage to be 14.2 volts at the top of the track.  The stall current for the gold motor is 1.4 amps and. The round motor is 1.8 amps.  Yours may vary slightly from these levels.  Clearly these motors with load will exceed the 0.7 amp threshold.  Remember, a dirty engine will increase the motor load.  Athearn BB engines are prone to truck tower bearing lock and axle gear cracking like but not as bad as the old P2K units.  These also increase the train load and thus the operating current. 
How should you respond to this message?  It must get down to life of the module.  At 2 amps, the life is zero, it fails.  Below 0.7 the life is indefinite.  Not infinite, but generally long enough to be adequate.  What is happening to the module life between 0.7 and 2.0 amps?  How should you respond?  Should there be another warning?  Say at 1.4 amps?  To keep you from killing the module. 
I have recently installed Rail Pro modules on three older units.  An Athearn Genesis, a P2K, and an Atlas Kato.  During the proof testing of these units, this warning was experienced during part of the test series.  These engines were freshly tuned and were excellent performers on DC.   How should one respond to this message?