Post a reply to the thread: Wye-Delta skelter
You may choose an icon for your message from this list
Please enter the name by which you would like to log-in and be known on this site.
Please enter a password for your user account. Note that passwords are case-sensitive.
Please enter a valid email address for yourself.
Will turn www.example.com into [URL]http://www.example.com[/URL].
Originally Posted by ga1279 The contactor size has nothing to with amps or volts (go figure) NEMA sizing only has to do with motor horsepower. Amps times volts times a factor = hp. It's the same thing. And a motor load is harder on the contacts than a resistive load. In general, good closed contacts at rated load current should read less than 30 mV, with bad reading more than 100 mV but I don't know if this rule applies to humongous contacts like these.
Wye-Delta (That's all Folks) I have no idea, except to say that since the chiller[s] have been in service since Jan 1982 I would not waste my time trying for a service bulletin or compensation. The original building owners (when the chillers were installed) were actually lead to believe that changing contacts every year was part of the annual inspection. I also find it curious that it took 27 years to find the real problem. In that time the owners spent enough money to replace both starters completely. Oh well life goes on.-GEO.
Wye-Delta (That's all Folks)
yeah it is scarey!!!!!!!!!!! Originally Posted by stickerhead Wonder how many others out there "were" like yours!
Originally Posted by ga1279 Stickerhead; Thanks for the comeback, but I had already had gotten my answers from Tech. Services @ Eaton Cutler- Hammer who originally manufactured the starter for Trane (according to Trane guidelines). Even in a Y/D starter all current in, matches all the current out, as in locked rotor and ramp up. The problem was not one of lack of acceleration on start-up, but undersized contactors, as the motor was up to speed within 10 seconds-GEO I'm closed Wonder how many others out there "were" like yours!
so the problem was indeed undersized contactors from trane?? is there a service bulletin?????????? Originally Posted by ga1279 Stickerhead; Thanks for the comeback, but I had already had gotten my answers from Tech. Services @ Eaton Cutler- Hammer who originally manufactured the starter for Trane (according to Trane guidelines). Even in a Y/D starter all current in, matches all the current out, as in locked rotor and ramp up. The problem was not one of lack of acceleration on start-up, but undersized contactors, as the motor was up to speed within 10 seconds-GEO I'm closed
Wye-Delta Epilog Stickerhead; Thanks for the comeback, but I had already had gotten my answers from Tech. Services @ Eaton Cutler- Hammer who originally manufactured the starter for Trane (according to Trane guidelines). Even in a Y/D starter all current in, matches all the current out, as in locked rotor and ramp up. The problem was not one of lack of acceleration on start-up, but undersized contactors, as the motor was up to speed within 10 seconds-GEO I'm closed
Wye-Delta Epilog
Originally Posted by ga1279 As promised I got all my answers today. The contactor size has nothing to with amps or volts (go figure) NEMA sizing only has to do with motor horsepower. The motor I'm dealing with is 240 horsepower and that is border line between a size 5 and 6 contactor, not a size 4 as is in there now. That would explain all the extra burnt contacts sets I found laying on the work bench. I think they have been changing contacts every year since 1982. That year also played a key role to my fact finding. That's the year Trane change venders with their starters from G/E to Cutler-Hammer, now Eaton, Cutler-Hammer. Ironic part of it all is the customer won't want to spend the money to upgrade to the right size contactors. It is their chiller and I'm only the messenger. Again thanks to all.-GEO 1st of all, it is 57% on each leg V x A x 1.73. That's why it is called a reduced voltage start because you have the windings in series. You have to remember, "S" is already pulled in before amperage is applied. 1M is pulled in by the aux of "S" and you are tying together 1/2 of a winding in series so the contact is not seeing the full brunt of current. I have seen this on a R-113, Carrier 19C that took almost one minute to get to speed. Scared the hell out of me the first time I started it because I had only been exposed to 460 volt chillers.
what?? 123 is bad for you???????????????? Originally Posted by Randy S. Methinks you right. I must have had a snootful of 123.
Methinks you right. I must have had a snootful of 123.
i thought it was 57.5%????????? Originally Posted by Randy S. Theoretically the "main" and "delta" contactors each only carry 67% of the rated full load when running. The "star" and "main" would be the ones taking the most beating on start up. Is there a big voltage drop at start up?
Wye-Delta Grand Finale' As promised I got all my answers today. The contactor size has nothing to with amps or volts (go figure) NEMA sizing only has to do with motor horsepower. The motor I'm dealing with is 240 horsepower and that is border line between a size 5 and 6 contactor, not a size 4 as is in there now. That would explain all the extra burnt contacts sets I found laying on the work bench. I think they have been changing contacts every year since 1982. That year also played a key role to my fact finding. That's the year Trane change venders with their starters from G/E to Cutler-Hammer, now Eaton, Cutler-Hammer. Ironic part of it all is the customer won't want to spend the money to upgrade to the right size contactors. It is their chiller and I'm only the messenger. Again thanks to all.-GEO
Wye-Delta Grand Finale'
Wye-Delta part V First off an apology to acjourneyman, I should learn to read a little closer. These are the original contactors according to the starter manufacturer Cutler-Hammer and the Trane starter ID #. That's why I plan on contacting them on Monday, hell I may call Trane also. The more the merrier. Guys, thanks alot for all your advice. It is truly appreciated-GEO
Wye-Delta part V
Wye-Delta part lV Randy, that is my thought too! But why is the 2M also burnt ? I think I'm going to try and contact Cutler-Hammer with the part #'s and see what they think. If you look at the large wire size involved compared to how small the contact area is. I would have thought I would get a lot more voltage drop at start-up and a slower acceleration time, but thats not the case at all. The contactors do say they can carry 1400 amps locked rotor, but that's at 480 volts. Anyway I appreciate your advice. Thanks-GEO.
Wye-Delta part lV
It is probably safe to assume that these are not the original contacts in contactors due to the age of chiller. Have they been replaced recently, when did this problem begin? Have you been the only one working on it, doing repairs? If they are not the original, or OEM replacement contacts they may be some aftermarket knock offs that have slightly different dimensions. This can cause less than adequate pressure between contact surfaces resulting in arcing. Someone may have elected to get "cheaper" contacts, or the originals were no longer available. Be carefull, you could be playing with an Arc Flash incident waiting to happen.
Possibly, it has something to do with the size of the transformer feeding the building. As others have said, the 208 current draw when starting is tremendous, and it just may be to do with the sizing of the starter contactors.
Wye-Delta part lll To all, Meg readings of 475,000,000-ohms to ground is pretty good as is 1,000,000,000 ohms between the windings (T1-T2,T1-T3 and T2-T3) As I said in my previous thread (part deux) all the shorting rings are tight and have been epoxied to the armature laminations from Cutler-Hammer. The wire termination to the contactors, from the contactors and overloads are not burnt or discolored in any way. The only part that is burnt are the actual contacts themselves. All three of the contacts on all three of the main contactors. The shorting (S), 1M and 2M. This leads me to believe that the contactors are too small for this application. Randy, I can type up a storm but I'm not the computer literate to put a picture here, wish I could. Thanks again-GEO
Wye-Delta part lll
PICTURE?
208 can always be a pain... especially when your inverted... i would be looking at a soft starter install if you are thinking about rebuilding any of these contactors... some care needs to be given on how to wire it into your chiller control... pay particular attention to your signal resitor circuit... being around a 208 starter and that kind of current in wye is always interesting... Stay safe...!
Definitely agree Randy, dis-colored copper is never good. Always clip back my motor connections. Good pick-up.
How about the shading coils on the iron core of the contactor? The copper loop thingy.
Forum Rules