Electro-Craft motor with newer drive

[Material guy]

I have a new MAX430 dc servo drive and I am trying to drive an Electro-Craft E650 dc motor with tach feedback. The MAX430 lights up the "high average current" LED with the E650 motor/tach. The motor was operating correctly with an older Electro-Craft drive which had lower capacity. The MAX430 drives an E650 motor on the other machine axis with no problem. Both motors are dc with tach feedback. Adjusting gain pots and jumpers according to the manual on the MAX430 works with the newer E652 motor but not with the E650. Both motors are not now supported by Rockwell Automation which bought Electro-Craft. Does anyone know what the problem is about using this drive with an E650 motor. I can supply the rest of the model number of each motor if that makes any difference. We have tried adjusting the gain etc. to match the drive to the motor but always get the "high average current" light and a shut down after the motor jerks or makes one or two turns.

[Al_The_Man]

Did you try and bench run this motor with the drive and a use either a battery box or very low voltage (1 cell etc). The best is a battery box, you can input very low voltage down to zero, low voltage signal should produce low mean current to the motor, This would also test the tach phasing as it almost sound like it is reversed tach signal.
Al.

[Material guy]

We ran the motor on the bench. Reversing the tach connections causes a run away condition. The E650 motor has around 6 ohms winding resistance and the newer E652 motor has slightly over 1 ohm.

[Al_The_Man]

On the bench with the tach connected correctly did it still error out will small signal, or what did it take to show an error?
If it errors out with low signal in, I would remove the brushes and blow it out with compressed air to clear any carbon build up, and check for resistance to ground, a megger would be best for this test.
Al.

[Material guy]

The MAX430 seems to require that it be hooked up to the motor in order for it not to light the red LED "high average current fault light". When it is hooked up to the E652 motor it works. When it is hooked to the E650 motor it lights up the LED and shuts down according to the manual in 1.8 seconds. The motor runs on plus/minus 10 volts. The winding resistance of the E650 motor is 6-7 ohms and the resistance of the E652 motor is about 1 ohm. The MAX430 gets 120 volt single phase input supply. The motor has a run away condition when the tach leads are reversed. It shuts down after a couple revolutions in the 1.8 seconds. The tach puts out a voltage when the shaft is rotated. The resistance of the motor goes up and down as the shaft is rotated both of these measurements indicate the motor is ok. I will blow dust out of the motor but I suspect that is not causing this problem. It appears that the MAX430 drive somehow is responding to the higher resistance and trying to put out a higher current which trips the "high average current" fault. It is encouraging that the general opinion is that the drive should drive a dc motor with a tach feedback. It is a mystery why the E650 motor seems to be incompatible with the MAX430 drive. I have not yet gotten an answer from Rockwell Automation to the question: Is the MAX430 compatible with the E650 motor? The EE who is helping on this problem has been out of town on business this week so I am a little disarmed about working on this set up at the moment. I hate throwing money at a problem when no one knows what is going on.

[Al_The_Man]

Is the tach volt/1krev the same, if not the tach adjust may need scaling if there is one.
Also if there is a gain pot. reduce this considerably to see if a difference can be seen.
Al.

[marcosmendes]

PLEASE .I need instruction manual electrocraft BSA series and MAX430 .
E-MAIL luctron@gmail.com
Thanks

[mike_Kilroy]

couple ideas since u seem willing to try stuff....

is ur drive 120v input separate from its logic supply? if so u can try sticking like 12vac from a small wall unit or whatever into the power for dc bus to try with lower dc bus. here is why....

drives have a min Inductance rating; running a motor with inductance too low can cause them to give this overcurrent indication. but if u drop the dc bus low enough you can run a lower L motor. ur 1ohm motor compared to ur 6 ohm motor is likely 30 times lower L (L changes by the square of the turns and since ur resistance is 6x less, chances are you have 6*6 or so less L also) and may be too low for that 160vdc bus. typical ratings on drives like that are aroun 1mh min.

to run low L motors ono these drives u can add an inductor in series with one of the motor leads to make it big enough to satisfy the drive. so, got any 1,2,5mh inductors u can stick in series for a test? No? wire that other motor arm leads in series - it has higher L - and it will make it high enough for a test.

last idea: how have u tuned the current loop in that drive? does it have a pot to turn? turn it? if current loop is set up for a given L motor and u stick one significantly different on it, the current loop will likely be unstable and oscillate. If it oscillaes bad enough it will be +/- current limit and so will then give error you are getting. can u tunbe I loop? turn pot if so or get manul ad find the R-C network components around it and add more cap!

tell us what happens...

[tkb11]

hey - what are the torque specs for the E652?

TIA