High overload capacity motors and drives

R

Thread Starter

Ricky Chang

I am looking for a AC servo drive/motor combination with high overload capacity in the 5kW and above power range, preferably 200% overload for 1.5 min and 300% for a couple of seconds. Does anyone has experience with such suppliers? Any information would help. Thanks.
 
Servo Ratings / overload are really just a numbers game and you cannot just pick a number based on this snapshot of ratings.

Calculate your peak load/time and your RMS torque requirements and select your system components based on these criteria. If the peak load
requirements are the limiting factor . . . use these to size the system components. If the RMS requirements are the limiting factor . . . you
get the idea.

Saying you need 200% or 300% ratings really doesn't mean much unless they are put into the context of duty cycle (Hence the need for RMS
calculations) Also you need a torque rating of 200% of what? Your nominal load? The servo motors continuous rating? If you are looking
at using a servo, are dynamics a consideration? You need to look at how much torque goes into accelerating the motor + load. Picking the motor
will give you an inertia which must be considered when accelerating or decelerating . . . I know I probably didn't answer your question, but,
unless you consider a few more questions, you will never get a satisfactory answer.

Ken Brown
Applied Motion Systems, Inc.
http://www.kinemation.com
 
B

BJ_Johnson/Appliedmotion

Try Yaskawa.

The Sigma II SGMGH motors with SDGH drives have 5.5 and 7.5kW ratings with 300% overload for 2 to 3 seconds and close to 100 seconds at 200%.

check www.yaskawa.com for data and local distributor info or email off line and I can put you in touch with a distributor in your area
 
R
> Servo Ratings / overload are really just a numbers game and you cannot just pick a number based on this snapshot of ratings.
> Calculate your peak load/time and your RMS torque requirements and select your system components based on these criteria. If the peak loadrequirements are the limiting factor . . . use these to size the system components. If the RMS requirements are the limiting factor . . . you
> get the idea.

You are absolutely correct. In my application both are important.

> Saying you need 200% or 300% ratings really doesn't mean much unless they are put into the context of duty cycle (Hence the need for RMS calculations) Also you need a torque rating of 200% of what? Your nominal load? The servo motors continuous rating?

The percentage is based on continuous ratings.

>If you are looking at using a servo, are dynamics a consideration? You need to look at how much torque goes into accelerating the motor + load. Picking the motor will give you an inertia which must be considered when accelerating or decelerating . . . I know I probably didn't answer your question, but, unless you consider a few more questions, you will never get a satisfactory answer.

motor inertia is also important because I also need high dynamics, and this is one of the reasons why I need higher overload
> Ken Brown
> Applied Motion Systems, Inc.
> http://www.kinemation.com

Actually it's very interesting that you brought up the RMS factor. I use this equation :

I rms = sqrt((I1^2*t1 + I2^2*t2 + I3......)/ time_total)

Is this correct? Is there any limitation(like the thermal time constant) to this equation?
 
R
> Try Yaskawa.
> The Sigma II SGMGH motors with SDGH drives have 5.5 and 7.5kW ratings with 300% overload for 2 to 3 seconds and close to 100 seconds at 200%.
> check www.yaskawa.com for data and local distributor info or email off line and I can put you in touch with a distributor in your area

I read the specifications for the motors downloaded from Yaskawa's website, but the overload factor max is only about 200% rated. Am I reading the right literature?
 
Look for a Servo motor & Drive supplied by INDRAMAT (German factory) These drives are well priced and are specially made for high performance power and overload. We have very good experience with these drives. Good Luck

Sisko Bos (Application Engineer)
 
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