lenze ac tech problem

dcam

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Apr 2012
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Merced Ca
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i am converting to frequency drives/motors from dc brush motors. they are driving old taylor conveyors........the problem im having is occasionally the new motors wont start when turned off for a while, the digital ref run enable is present at actech drive when this problem occurs. i have matched the specs from old baldor motors to new motor...............has anyone else ran into this? are freq drives inherently less torque ? apologize for topic not being directly plc related, ive had good experiences with peoples responses here though.

ps....tried maxing out current limiter and ramp up on lenze actech????:cry:
 
I do not know what a taylor conveyer is. However you say old. I think you would do well by measuring the torque demand at the motor shaft on these units. With old bearings etc the torque demand may be higher than you think. The DC motors may have been able to overcome the breakout torque especially so if they are series motors.

So need to know what type DC motors were used.

Also are you starting conveyers full or do you let them empty and then shutdown.

What is the material conveyed?

You may need to add some HP to motor rating when switching to AC.
 
packaged trayed poultry.....just looking at other motor, marathon electric 5K49DN4130....think amp rating is wrong?????? appreciate all of your patience.
 
i am converting to frequency drives/motors from dc brush motors. they are driving old taylor conveyors........the problem im having is occasionally the new motors wont start when turned off for a while, the digital ref run enable is present at actech drive when this problem occurs. i have matched the specs from old baldor motors to new motor...............has anyone else ran into this? are freq drives inherently less torque ? apologize for topic not being directly plc related, ive had good experiences with peoples responses here though.

ps....tried maxing out current limiter and ramp up on lenze actech????:cry:

Did your motor stalled or did it not run at all? You can put a clamp meter onto one of the motor leads and see if there's any current. The motor is stalled if it is not running and there is current. If this is the case, then upgrade your motor to a higher horse power motor.

If the motor is not stalled, then something is up with the system logic.
 
its a breakout torque issue, ac tech controled by little micro810 plc, its getting run enable and the preset speeds are changing on led, havent used ac tech freq drives before, perhaps its a setting im unfamiliar with???
 
If I remember correctly, the starting torque of a DC motor is greater than the starting torque of an AC motor given that everything else is the same.

Some AC drive allows you to tweak the torque profile. This allows you configure the drive to output more current initially which gives you more starting torque. Hopefully that will get the motor spinning. However be careful not to burn up your motor.

If it is up to me, I would upgrade the motor to a higher horsepower motor
 
these Marathon motors are cheap, thinku guys r right. gonna go to a third HP....once again u have all been a great help thx
 
Unfortunately, you have chosen a brand of VFD with near-zero tech support in North America. Despite that, we can probably help you.

First, if you are sure that the drive has energized the motor and the motor simply isn't making enough torque to break the load into motion, then look in the drive parameters for something that sounds like Torque Boost or Manual Voltage Boost. This parameter changes the ratio of voltage and frequency to give a little extra at slow speeds and starting. You can raise this to the current limit of the drive not to exceed 200% of motor FLA. Going above that will fault the drive or cause the torque to go down rather that further up (motor magnetics are saturated).

Second, if that doesn't work or isn't available, then look into increasing the mechanical reduction ratio between the motor and the load by about 50%. That way the motor will have to turn 50% faster to get the conveyor to top speed. Then reprogram the drive to sweep between 0 and 90hz. That will cause the motor to run up to 150% speed. Don't worry about the motor. It will be just fine. Because of the higher mechanical ratio, the starting torque at the conveyor is 50% higher. And the torque at the load is higher too up to the 90hz point where it drops down to the same torque as before at 60hz.

Third, if neither of the above is possible, change out the motor for a 1200rpm unit instead of the present 1800rpm. This will result in the same as in 2 above. Run this motor to 90hz. At start, it makes 50% more torque than the 1800rpm unit and the same torque at 90hz. No need to increase the hp from the present value.

Finally, if none of the above can be done, increase the motor hp to 1/3 or 1/2hp (they're all in a 56 frame). Watch out for the amps tho. You might have to buy a bigger drive to match the bigger motor.
 
lessened acceleration time and increased min freq to just under lowest operating freq. I think problem is gone.......thanks everyone.
 
Neither of those settings increase starting torque. However, they might lessen the stall time to acceptable values.

Either way, if it's operating satisfactorily, that's good and all that matters!
 
had accel boost maxed from beginning, this was first of 16 lines im upgrading ,expected bugs,next line will get 1/3 HP , that should fix issue i think???
 
had accel boost maxed from beginning, this was first of 16 lines im upgrading ,expected bugs,next line will get 1/3 HP , that should fix issue i think???

so you fixed the problem by decrease the accel time? If this is the case, then your drive probably tripped @ startup with the old accel time.
 

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