Braking resistor for drive.

[AndEdtec]

"AC Drives that use a chopper and resistor to enable Quadrant II and IV operation aren't regenerative in the sense of delivering power back to the line, but are regenerative in that they can actively remove power from the driven load."


Thanks, I have learn't so much more about drives.
I was interested about the fact you regenerate back to the line hence using less energy.

The drive I bought is programable and is an sew movidrive.
It is a four quadrant drive. But I never new what this meant.

If it is four quadrant why does it still use a snubber?

I will let you know how I get on when I have commissioned it.

Please contact me or post to this topic if your interested in what I'm doing.

Thanks again for a helping me understand the technology I use.
Andy

 

[allscott]

I know enough about drives to know that there is a lot more to know about drives than I know. Make sense?

Somebody with more drive experience than I have will probably answer your previous question better than I can but because I have some experience with SEW I am curious as to why you are using a Movidrive.

As I understand it a Movidrive is SEW's closed loop vector drive. Are you going to be closing the control loop with an encoder? Do you need vector control?

I have used SEW's movitrac 31C flavour of drive and it should be capable (and less expensive) than the movidrive for your application. As a side note, the previous plant I worked at had about 40 of these drives and we blew one up about twice a month. I never did figure out whether or not it was the fault of the drive or the installation/application, the AB 1336 drives that we used doing the same thing never had a problem.

 

[kamenges]

Originally posted by AndEdtec:

If it is four quadrant why does it still use a snubber?

A drive being single quadrant, two quadrant or four quadrant defines the relationship of the drive to the motor in terms of how torque is generated relative to motor direction. The need for a snubber or a line regen package defines how the drive gets rid of energy possibly coming back from the motor. 'Four quadrant' doesn't necessarily mean 'line regenerative'.

Keith

 

[AndEdtec]

I'm using the movidrive in closed loop with an encoder, also i have installed the optional I/O card.

I need to stop the load in upto ten different positions.
The time I have to build the panel write program install motor/gearbox is only 3-4 weeks. I'm a maintenance electrician as well as being responsible for new builds.

With the movi drive all I have to do for positioning is have different sets of parameters in the drive such as distance and desired time from start to stop and the drive will work out accel decel, basicly do it all for me.

Then all I have to do is send signals from my plc to control it.

Ok it could be done with a plc and simpler drve but why bother?
My plc is already using most of it's IO and already has large program in it.

 

[Colossalnut]

Bogey Car

Hey Andy! I was just wondering what the purpose of the "bogey car" is. Will you be loading it, unloading it, or what? I'm not familiar with that term... Though the car is rather small additional weight could pose a problem also...

 

[Colossalnut]

I also neglected to ask about the motor itself and how it will be coupled to the load. Direct, gearbox, chain-driven, or belts... Just curious...

 

[AndEdtec]

The "bogey car" is simply like a train carriage.
It has two wheels.
It is pulled and pushed by a crank arm and push rod.

 

[Colossalnut]

But what does this car actually DO? For some reason I'm intrigued with your project and merely want to more clearly understand what you're trying to accomplish. Concerning the drive and the braking resistor (your original query) you've already received some of the best information and advice available. Are these guys GREAT, or what?!!!
I was just wondering (again... I wonder alot!) if you're planning to rely entirely upon your encoder for positioning or if you're utilizing limit switches also. I think that you mentioned ten stops...How precise do these stops have to be? Is this an existing system that you're modifying or a new installation? Is your encoder going to be coupled with the motor or on the driven device? Any slop in the mechanical portion of your project will quite likely have you pulling your hair out if you rely solely on your encoder. If you were using a more precise method of movement like a ball screw (impractical, I know) or a linear gear with the encoder mounted to the rotary gear on the drive shaft then an encoder alone might be applicable, but you'd still need limit switches at the extremes for over-travel protection at the least.
In the environment you're dealing with I'd go with cylindrical threaded inductive proximity switches with plug-in, threaded connectors at each station opposed to sealed pre-wired switches because over time you will be replacing damaged switches and cables individually as the need arises. The cables are damaged more often than the switch, usually, and it's much cheaper to replace by itself.

 

[AndEdtec]

Hi, I have more time now to tell you all about my project.


Thw application is an additon to an existing concrete block handling system.

I have used this method to push and pull the bogey car on several machines in the plant with very good results.

I normaly just use a inverter with two proximty switches (IFM Quadranorn IG5954, which is the best inductive sensor around) and an over travel sensor.

There is very little mechanicle wear, we replace the rail that the car runs on now and again.

But for this application I'm going to use the field oriented drive with enconder attacted on to the motor shaft by the fan.

When I say 10 different positons it will only ever go to two positions but will have the setting for all those other postions in the drive.

Let me explain, When making the largest product it will start at positon one and move to positon ten.

When making the middle sized product it will go from 2 to ten.

and the smallest product from 8 to 10.#
IT NEVER GOOES FROM SAY 1 TO3 THEN 3 TO 6 THEN 6 TO 2.

So in my system i reset the encoder value evey time it does one movement.

I hope this helps you understand.

 

[Colossalnut]

Thanx Andy! I was just curious.... but still think that encoder is going to be a pain in the *** banghead lolis
Let me know how it all works out!

 

[LIP]

test

 

[SEW]

attn: allscot

Hello Allscott,

I am sorry about your experience with SEW VFD's. I work for them. Quality and service is one thing that we take extremely seriously.
We have sold thousands and thousands of Movitrac 31C's (discontinued for regular sale), MC07's, MOVIDRIVE VFD's in Canada over the last few years and I can honestly state that what you have experienced indicates something very unusual. Perhaps your electrical network in your facility is a Delta network (ungrounded)?

Please call our toll free number in Canada at 1-800-567-8039 and ask for the engineering manager or one of the electrical engineers.

Best regards.

 

[rsdoran]

rdrast, may I use that Regenerative drive post you made. I will add credit in any fashion you request.