YCAS vfd conversion?
Has anyone ever considered or accomplished this for compressor starting?
The benefits would be great, reduced inrush, no more replacing hard to get and undersized wye delta contactors..
You would configure the vfd for fast ramp up for lubrication demands, still using the slide valve for capacity control, and run the vfd wide open, (a soft starter).
It would require some creative control circuit changes..
You could probably still use the motor protector in addition to the vfd for motor protection.
An external weather tite cabinet would be needed, as well as the good appliance wire to connect the drive.
The coil voltage for the delta connection could be used to initiate the drive?
Someday, I hope to be just as brave as Harry Stamper.
Never done it or considered it. Are you talking about completely gutting the panel and using all after market components or what? You'll have to adequately provide cooling for the drive, compared to the YCAV/YCIV the drives are cooled by a coolant loop. And don't forget panel space for mounting a drive. I'd run shielded cable. How are you going to set up the parameters on the drive? The drive won't communicate with the panel it'll just start. I'd be concerned about your lift (motor cooling and oil pressure), and setting up a minimum compressor speed. Comparing the YCAV/YCIV the don't have slide valves. If it were me, I don't know if I'd even f*** with it. You're looking at a lot of cost on a project with unknown results. Inovative idea though.
Sic Semper Tyrannis.
Wouldn't it be easier and less headache to maybe try to retrofit a larger wye-delta starter?
Thanks for the reply's from some of my fav guys on here.
It would certainly be easier to retrofit heavier starting components, however, consider that now the unit is using contactors (ABB) that are *just* large enough and difficult to obtain, they dont last for years, and moving up to an Allen Bradley starter of good size would last the life of the machine, however would cost the same or more than an 80hp Yaskawa drive.
Drive cooling would be accomplished by the built in fan, the drive would not be used for capacity control, it would simply start, ramp up rather quickly, and run at 60hz.
You wouldnt have to gut the York panel, only removing the 3 contactors for the compressor. The wye delta relay outputs from the controller and aux contacts from the existing contactors would have to be dealt with so the micro would be happy. It may not even be possible to satisfy the micro without getting crazy with relays and timers. (faking the computer out) The micro has to see the transition and the low starting current from the vfd may cause trips.
Ya its probly not a cost effective solution and DEF has unknown results, HAHA!
I think we'll just do a proposal for the larger contactors. These units short cycle a lot during low loads b/c the control system enables both chillers at all times, another contractor does the controls, I need to sneak in down at the workstation and see if I can modify the lead/lag parameters and chiller enabling! Or I could just hit the black rocker switch and keep one unit off when its cool out. But its definately the short cycling that is tearing up the contactors, compressors, and spiking their electricity demand.
Running a VSD at 60 Hz. doesn't make sense. Any electricity you saved on the ramp up would be gobbled up in short order once you were running at 60 Hz. Remember there is a loss associated with converting AC to DC and back to AC. Not sure what that cost is now, but in the past it was 6%. So a VSD running at 60 Hz. is consuming 6% more than a star delta starter. It may be less now, but there's no free lunch and you cannot convert AC to DC and back to AC without paying some penalty.
And, to me, that's just the beginning. You'd be better off selling the customer a new machine. Then you'd be talking real energy savings.
Very good point.
Originally Posted by KnewYork
However, these days, a vfd is more than just a variable frequency drive, it is also the ultimate starter and motor protector, and the cost is coming down and down vs the cost is going up and up on heavy duty American made mechanical starters.
So in this case, I was just toying with the idea of VFD starting, for reduced inrush, and wear and tear on the compressors themselves and the switchgear.
I think the lubrication would be fine is you could get the compressor up to speed in maybe 5 seconds or less.
But ya its just brainstorming for a customer.
You will be putting earrings and necklaces on a pig! We have almost got rid of all them in our area, dont even think about replacing the compressor with a stock compressor. You will be on your own. Just my 2 cents.
A LITTLE BIT OF STUPID GOES A LONG WAY!
Well I certainly appreciate others expertise and experience, the dxs compressor not so legendary huh, or that unit in general? Care to elaborate some more? I've heard of folks installing hanbell screws, aren't those a friggen Chinese design?
Originally Posted by sargent york
These units are getting a lil long in the tooth, is the new York screw with vfd's the way to go? I haven't seen one yet.
If the chiller is in an accesable location, I would advise customer to start budgeting for a new machine. If it is in inaccessable location, has lost compressor and cannot get replacement chiller, then a retro-fit to another brand of compressor and controls may be justified. We have been in both positions. We have retro'ed one with handbell compressor and magnum controller. Conversion was succesful in that it is more reliable and more efficent. Cost around $60k. We have had good results from the York VFD chillers, parts are very expensive however when needed. I was working for York when YCAS was introduced and we had H#$L keepingthem up and running from the very beginning. If you are losing contactors you may well have compressor problems now. Just my 2 cents.
A LITTLE BIT OF STUPID GOES A LONG WAY!
Good information sargent york, thank you for taking the time to reply!
I know this thread is a little old. We are in about to submit a proposal to retrofit a YCAS with a Hanbell or Bitzer screw on a vfd. The existing York controls send a 0-10 vdc to the slide valve on the dxs, perfect to modulate a drive. The slide valve on the new compressor would be locked out at 100%. The compressor would have to ramp up to a pre determined minimum speed in about 5 seconds on start up, after the 0-10 v signal surpasses the minimum speed the drive will modulate to control the load. The existing CT would be utilized to satisfy the controls but the contacts for the Low mp/hp would now be in series with the hp switch and vfd fault contacts. The existing controls will still modulate the fans and all sensors could still be utilized. Right now we have two machines with across the line starters, close to 900 LRA. We have had probably 6 compressor failures on 4 compressors since installed so we are looking for a solution. Questions or comments are welcomed.
Sounds like an interesting project, keep us posted. Im not a fan of DXS compressors. Some seem to last forever, some don't last at all. If your machine has EXV's you might want to throw those in the same trash can the old compressors go in. Install LL sol valve, and TXV. Seen too many suction temp sensors go out(reading high), and EXV's flood compressors. Im not too familiar with Hanbell, or Bitzer. What type of drives are you using?