AC drives

[Vipul19]

I am trying to decide which drive to buy and they all seem to be the same. Can someone help me to choose between:

Vacon
Benshaw
Allen Bradley

I have a fairly simple low voltage application and need a drive to run a 5hp motor driving a conveyor back and forth. 1000 cycles per day...need sensorless control (encoder feedback from the motor).

Not sure what else I should be considering.

Any recommendations are welcome!

Thanks.

 

[Skogsgurra]

Is the conveyor horizontal? No need to brake? Then you should look at local support, if it can survive in your environment and the price.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Vipul19]

It is horizontal, but our return speeds will be around 300ft/min. I would guess that we do need braking?

Vacon is local and we were leaning this way, but I thought I would ask to see if anyone had any experience either way with the different options.

I found Allen Bradley to be extremely bad with respect to technical support and trying to find the right person to speak with, so that was a good indication of the service that might be expected after the purchase.

 

[Skogsgurra]

Vacon is OK. No probs with their inverters. They have the necessary brake chopper, but you must order it. Not automatically built in in the inverter.

They also have DC braking and 'Flux Braking'. I think both could work. Also at 1000 cycles/day.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[DickDV]

Go with youever gives you the best local support. Benshaw is relabeled LG from Korea but I don't mean to say that that is a bad thing. And, yes, AB is going to be difficult and expensive. Vacon doesn't have much support in North America but, if they have your home area covered well, that's all that matters.

At only 5hp, most drives will have the brake chopper built in. Then you only need to add the resistor. If your selections don't have that, you will need to add the option cost, whatever it is, to the price of the drive.

 

[automatic2]

need sensorless control (encoder feedback from the motor).

is this not a contradiction?

 

[jraef]

Vacon, USED TO not have much support in North America because they had an exclusive contract that had Cutler Hammer selling their drives. When that exclusivity ran out a few years ago, they entered the US market on their own by buying an existing product line and enhancing it. So what is Vacon US is what used to be known as TB Woods, a very well known and very well respected drive line that was sold primarily through mechanical distribution chains (because TB Woods also was / is a gearbox mfr). I have used a lot of the TB Woods E-Trac drives (now called the Vacon X Series) over the years. Not fancy, but very reliable.

15 some odd years ago when LG was first looking for a marketing program for their VFDs in the US, they approached my employer to brand label them. We did not have a Sensorless Vector Control drive at the time and this seemed like a solution for us. The problem was, the drive they wanted to have us market as an SVC drive was in fact, a Scalar drive with automatic voltage boost. In other words they lied. They came back and apologized, saying that they didn't want to miss the window of opportunity when their SVC drive was not yet ready.

They later went on to offer the program to Benshaw. I'm sure they have fixed that problem by now, but I have never trusted them since. Benshaw also brand-labels the LG (now called LSIS) contactors as well. When Benshaw first announced it, they told everyone they had an exclusive with LG and helped pay for the R&D to develop it. At the trade show where Benshaw rolled out the new contactor product line, LG approached us with the same "exclusive" deal! I felt sorry for the guys at Benshaw; LG has since gone on to set up several "exclusive" deals on those too. That lead me to not want to trust anything they say...

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[controlsdude]

I vote for local support.
then cost
most drives are the same, some better some worse

 

[LionelHutz]

An encoder is a sensor so encoder feedback is not sensorless control.

Pick the manufacturer with the best support. I'm probably not the best person to ask how good a drive is. They are all cut back to the bare minimum required to produce the cheapest possible product and my guess would be you'll run at least a 10% chance of needing to invoke the warranty. So, you need to pick the manufacturer with readily available support.

Oddly enough, the older TB Woods drives (like the WF2) used a main controller IC purchased and licensed from Vacon. The new X4 and X5 drives were developed to eliminate that IC and then the TB Woods drive product was purchased by Vacon. I'm not sure if any software support from Vacon went into the X series drives but the two companies had a history before the purchase.

I don't believe Benshaw paid any R&D for the LS contactor line. They did their own UL testing and own their own UL files on that line. Other people could sell them but either they or LS would have to UL test to get their own listing.

 

[jraef]

I don't believe Benshaw paid any R&D for the LS contactor line. They did their own UL testing and own their own UL files on that line. Other people could sell them but either they or LS would have to UL test to get their own listing.

I don't disagree with that, but this was the marketing spin they spewed at the time they released it. I think they genuinely believed they had an exclusive at the time. My point was the issue of LG apparently not understanding the term "exclusive", being that they were offering us the same exclusivity.

I should have pitched my vote for the local support issue too, that's usually my first response. There is nothing more frustrating than not knowing what's going on with something as complex as a VFD and having to wait on hold for 30 minutes just to speak with someone who may or may not speak your language fluently. Ask your supplier up front if they have an on-staff specialist who understands the product. If they rely on the manufacturer for all support, you may as well buy from a cheap on-line source (something I wholey discourage) and take your chances at being your own Tech Support guru.

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[LionelHutz]

I think the LG contactor exclusive was just wishful thinking.

One thing I didn't mention. If you want an encoder then that knocks Benshaw out and also limits you in the Vacon and AB product lines you can use. This also means getting proper support for those specific products, especially issues with tuning the closed loop, will be much more difficult.

 

[DickDV]

Might be time to look into the ABB ACS355 product with an encoder feedback card. (of course, I'd be prejudiced, being an ABB rep)!

 

[Vipul19]

Sorry I was not clear on the encoder/sensor thing.


1. We plan on signalling running the drive at around 50 - 60Hz for 2 – 2.5 sec. – This is the inital approach to the cutting heads
2. Then 5-10Hz for about 30sec – 40 secs – This is the cutting phase
3. Then 120 Hz for about 2-3secs. – This is the final departure from the cutting heads
4. Then 0Hz for about 5 secs – This is unloading the cut material
5. Then 120Hz for about 5 secs – This is the return of the cart for the next cycle
Then 0Hz for about 5-10secs – This is the wait for loading the new material


Do I need encoder?

 

[Vipul19]

I started another post, but will mention here too.

We have come up with 10HP and 49:1 gear reducer. Inverter duty motors seems to work with respect to lowest required rpm (15:1 constant torque is more than enough. I only need 11:1).

Based on my post above, I was wondering if anyone can give me an idea of whether an encoder type precision is required?

Thanks to everyone so far. It has helped a lot (especially since I am actually a structural engineer).

Also thoughts on braking requirements with the VFD based on what I am trying to do?

Cheers.