# dc motor control fault



## John Valdes (May 17, 2007)

*Are you using field weakening*?
Is the motor holding speed?
Have you ohmed out the field windings?
Are you down? Are you reseting the fault and then it runs?
Has the motor operated fine before?
Any motor connection or motor changes?

Most DC motors have the field winding specs right on the motor nameplate. So look for that and take some measurements.

Make sure the field windings are correctly connected and check the field weakening device or if on board the drive, the parameters for field weakening.

You could disable field weakening and connect the field windings directly to the drive and run it like that to see.
Verifying the field windings are okay is your first obligation. Then if you are certain they are good, you can start looking for the culprit.


----------



## mpirkle (Jul 15, 2013)

should have stated this is an intermittent problem 

some days speed is fine others I get this fault and it shuts out control of motor speed untill we power the machine down.this takes 45 min for it to coast down the only time we stop the machine is for faults and monthly maintenance normally we stop feeding material and let it keep spinning 
*measured windings at 160ohm 
*megged to ground >550M
*motor nameplate specs field amps at 1.9a cold 1.3a hot
*motor has been in place probably 10 years
*not using field weakening


----------



## JRaef (Mar 23, 2009)

mpirkle said:


> should have stated this is an intermittent problem ...
> ...
> *not using field weakening


That makes me suspect a nascent problem with your field supply in the drive. Those sort of things only get worse from my experience, time to address it now while it is still serviceable.


----------



## Jack30802 (Jul 6, 2013)

I have had back drive trip out intermittent like that when the machine wash cycle is not working operators shut down with out cleaning bowl


----------



## IslandWire (Aug 3, 2013)

*DC Field Fault*

1) Do you have a field power supply? Is the Imax setting correct and is the output DC correct?
2) Can you do a DC Current logging on the motor armature to see if you have a loading/no loading condition. That would affect your need for Field current and possibly trip out your drive. If this is the case adjust those parameters.
3) Monitor the DC Field current and analyze then compare it to the parameters that would cause the field fault to occur. 

Note: Logger can solve any problem if used properly...


----------



## nknj3181 (Jul 19, 2013)

*check feedback side*

here there,

if in your motor control system, techo-generator is used. than check its connection. if you find connection of than check its carbon brush. if your techo-generator feedback is open-circuited than motor runs on high speed.


----------



## Safari (Jul 9, 2013)

mpirkle said:


> ok i've got a 40hp dc motor on a simoreg control that keeps faulting on "< 50% field current" (F005)
> I'm not that familiar with dc drives what could cause this
> it's a backdrive motor on a dewatering centrifuge if any of you are wastewater experts


 
Possible fault causes​• ​​Threshold for phase failure (P353) set incorrectly​
• ​​Field phase failed​
• ​​Line contactor opened during operation​
• ​​Fuse blown in the field circuit​
• ​​Field current controller and/or field current precontrol not optimized or badly optimized (check P112, P253 to P256; possibly
execute current controller optimization)​
• ​​Check P396 (field current monitoring threshold) and P397 (field current monitoring time)​
• ​​If the fault value is 6: Offset fault in the actual field current value sensing, relevant parameter: P825.i01-i03 (Offset depends
on P076.i02) or P394, P395 (Threshold and hysteresis for message I_field < I_field_min) must be checked​
• ​​If the fault value is 7: Circuit for the "new" field direction is interrupted (e.g. because the contactor for "new" field direction​
does not pick up), P398, P399 (Threshold and hysteresis for message I_field < I_field_x) must be checked


----------



## mpirkle (Jul 15, 2013)

drive was removed and sent in for testing. waiting on parts to repair an internal issue 
I'll update when I get it back and know what went wrong


----------



## Safari (Jul 9, 2013)

mpirkle said:


> drive was removed and sent in for testing. waiting on parts to repair an internal issue
> I'll update when I get it back and know what went wrong


its good you took it for testing but i doubt if it has any problem.i will bet its not an internal problem.we have experienced the same fault F005 where i work. 
let me ask do you have dc contactors after the drive? well if you do then you may want to check the contacts BOTH for the field and armature dc contactors you check the positive and negative poles contacts, if they wear out they tend not to close and hence you have that error. 

if you dont have dc contactors after the drive then i assume the cables from the drive run directly to the dc motor,then you probably have to check the cables, the F005 ERROR IS MOSTLY RELATED TO field supply not getting voltage(either P or N).THAT IS IF YOUR parameters are ok.


----------



## mpirkle (Jul 15, 2013)

no contactors after the drive and I set up a logging meter on the field conductors that never showed a drop in current 
fault was f005 p047 was showing word 4 
all other parameters were correct.
I believe the problem was on the board that reads the field current.


----------



## Safari (Jul 9, 2013)

mpirkle said:


> no contactors after the drive and I set up a logging meter on the field conductors that never showed a drop in current
> fault was f005 p047 was showing word 4
> all other parameters were correct.
> I believe the problem was on the board that reads the field current.


ok just curious did you ever get any alarms on the drive prior to the FOO5 Fault?


----------



## mpirkle (Jul 15, 2013)

no alarms. it started doing this maybe once a month a gradually got more frequent when we sent it out it was tripping once a day


----------



## Safari (Jul 9, 2013)

mpirkle said:


> no alarms. it started doing this maybe once a month a gradually got more frequent when we sent it out it was tripping once a day


ok thanks waiting for feedback from the experts and please let us Know the solution to the problem when it gets back 

we have so many dc motors where i work we have one 850kw dc motor working on 6R7O SIMOREG DRVES,95KW AND 55KW in total are 10. 
the company purchased 6R80 SIMOREG DRIVES WE ARE YET TO WORK ON THEM


----------



## mpirkle (Jul 15, 2013)

just picked the drive up, problem was some bad capacitors on the main control board/and output power supply also bad solder joints.
I'll be reinstalling tomorrow hopefully it will behave better now


----------



## Safari (Jul 9, 2013)

mpirkle said:


> just picked the drive up, problem was some bad capacitors on the main control board/and output power supply also bad solder joints.
> I'll be reinstalling tomorrow hopefully it will behave better now


ok gud to know thanks,strange though


----------

