DCservomotor run away

[kkilst]

DC servo sytem with 70vdc power supply and gecko320 (logitrol cnc 10 amps system), retrofit into 3 axes cnc router, system run ok for about 1 month. But problem encounter afterwards,
when enable (engaged motor armature), suddenly one of the dc electrocraft motor
(y-axis) run away at full speed.
can any body tell me what went wrong, advice is gratelly appreciated.
michael

[NC Cams]

Make sure you still have feedback from the motor/encoder to drive.

If the controller told motor to go someplace, it will go until the encoder tells the control/PC that it got there.

If you lose feedback, the motor thinks system didn't move and it runs faster to make it catch up in a vicious spiral until you shut it down or it hits something which either stalls it, breaks it or E-stops it.....

[Al_The_Man]

Encoder failure? No feedback.
Al.

[mlaws1172]

If you have "ERR/RES" jumpered to "ENC+" remove the jumper. You will have to put 5V to the Gecko to reset it, But if the encoder is faulting it will let you know. That is it will let you know if you are missing steps.
mike

[kkilst]

Thank your prompt response.
So this is due to faulty Renco encoder ? What is the likely cause of this problem ?
Is it due to not properly ground controller, or Gecko drive (Current Limit Tripot=20A Default
value) deliver too much current to the 900 oz-in ??? amperage DC servomotor.
Closed-loop system with Gecko drive does not have the provision of detecting faulty encoder
with run away motor, is it not dangerous if we use this system to cut metal ?
Michael

[NC Cams]

ANY machine that runs away/out of control is DANGEROUS - but the carnage can be fun to watch develop, from a far that is...

If you choose to run it until something "smokes", be sure to watch out for flying debris...

[kkilst]

Not until carnage or smoke, because toggle switch being disengaged immediately. Any advice to overcome this, GERC (Error/Reset) add-on
or BreakOut-Board can be any help ..........

[Bubba]

When I first setup my machine, I had a simular problem. In my case, I was using an encoder that had a current draw of 120 ma. I did not realize this and had hooked it to the gecko per normal.
Geckos are listed to supply a max of 50ma. It worked for a period of time and then started malfunctioning.
Check the current draw on the Rencos and if it is over 50ma, you will need to supply them with a seperate power supply (read the manual for proper connections)

[kkilst]

Attn:Country Bubba
Thank you very much for your valuable suggestions !!!

[Bubba]

Hope it helps!