New Panel

Hi guys - I was asked by my boss to design a new panel for a small-mid size machine. I am in the process of laying out the I/O and transformer sizing! "btw this is my first panel I am so excited " I am referencing my work to about 20 other panels made by 2 machine builders that we use at our facility. I have really well hands-on on PLC setup, integration as well as safety. I have not done anything from scratch thu. I have read the New Panel Thread and its really helping me out. I have few questions and I was wondering if I could find answers to them in here.



1) As far as machine lightning goes! do I have to have it on a separate transformer? Note that this is what machine builders did on every single panel we have in here

2) I understand that the PLC power unit and data exchange units "eg, Network Hubs and Serial Port Hubs" have to go to its own transformer and should have a surge suppressor "Is it because they have a high K-Factor for that transformer?". Will it hurt if I wire my panel lighting to that transformer or I have to have it separate?

3) My biggest problem is transformer drawings! I guess it’s kind of easy for me to copy and paste but I don't really want to do that I would really like to understand why each transformer was wired in a certain way and different from the other one! I can post different transformer wiring schematics that we use here if someone can offer some help on it!

4) For single transformer wiring on the primary side "on a 3phase 575 main buss line 60Hz" some transformers where wired to leg 1 and 2 , some on leg 1 and 3 “off of the main buss line”. Correct me if I am wrong! But this is done to distribute the load on the main buss line when multiple transformers are connected to it? This will give me different phases for each 120VAC on the secondary side? 30degrees leading or lagging? is there a thumb rule for this practice? and why?



Thank you for your help,

Y@S!

since most transformers (for machines, anyway) are single phase, it doesn't matter which two phases you feed them with...even if you have a high leg in your 480V system. It is common to split the phases when using multiple transformers, and it is usually done to balance the load of the main, not the secondary. Example : XFRMR 1 on phase 1 & 3, XFRMR 2 on 2 & 3, XFRMR 3 on 1 & 2, etc.

Lighting should be on it's own transformer, separate from your control transformer...the reason should be obvious. If a light shorts out, you don't want your machine down because of this.

Wiring of the transformers depend on input voltage & desired output voltage...the primary is indicated by the taps marked H1,H2,H3,H4. The secondary is indicated by X1,X2,X3,X4. Some transformers only have two wires (or terminals) on the primary/secondary, and these are voltage specific. Check the nameplate of the transformer for the connection diagram.

Also, call your local supply house & ask for an Ugly's Electrical Reference book...runs about $8, and among other things, has the calculations for sizing your transformer according to load demand (i.e., the kVA rating). Hope this helps. If not ask more spefic questions!

Call your

Be sure and check out this thread to which many here contributed some really great panel adivce and experience.

http://www.plctalk.net/qanda/showthread.php?t=18737

Thank you for your reply. I will be picking up the book for sure this week, thank you for the suggestion stasis.

Another question: I have a main panel that has a main disconnect and houses all the OP transformers "This is an existing Panel". now If I were to add another transformer a 575- 3X430Vac to that OP that has a main dissconnect and feed the 3X430Vac to a remote J-box that houses torque tools that run on 3X430Vac.Do I have to add another disconnect to the remote box? is there a spec as far as size of panel box vs. voltage within the box?

Thank you again

you have autocad???lay it all out and see what you have while its a work in project without drilling a hole!

Fred Raud

POWER_PACKED said:

Thank you for your reply. I will be picking up the book for sure this week, thank you for the suggestion stasis.

Another question: I have a main panel that has a main disconnect and houses all the OP transformers "This is an existing Panel". now If I were to add another transformer a 575- 3X430Vac to that OP that has a main dissconnect and feed the 3X430Vac to a remote J-box that houses torque tools that run on 3X430Vac.Do I have to add another disconnect to the remote box? is there a spec as far as size of panel box vs. voltage within the box?

Thank you again

Click to expand...

just remember that this comes from the Nation Electrical Code, not sure if it is applied in Canada...

You have to have a local disconnect if you are more than 100' from the main OR not in sight of the main. 'In sight of' is defined as a linear path without obstruction.
There is no spec as far as size of box where voltage is concerned, but the size of wiring & number of joints will determine the size of box. Check the tables in the back of the NEC book, IIRC it's Chapter 9.

Ampacity determines wire/breaker/fuse/disconnect size, wire size determines conduit/box size.

stasis I went to chapters to pick up Ugly's book but they don't have it or they said: Its Temporary Unavailable! "Chapters is a fairly large Book store here in Canada" so I went to amazon.ca and it was for 70$ used lol so then I went to amazon.com and it was as you said for 10$ but I can't ship it to canada!!!I guess I will try ebay next!

Another transformer question question:

The panel will have torque tool controllers that requires a

2.5KVA phase 240 60Hz step down transformer from our main buss line @ 575 60Hz. the torque tool controllers must have a PE conductor! My question would be what is the most appropriate configuration for the transformer? wye-wye? Delta-Delta? Wye-Delta? or Delta-Wye? I need to make sure before I proceed that I am getting the right stuff.



Thank you again,

Y@S!

by PE conductor, do you mean Primary Earth? If so, this is AKA ground,earth bond, etc.

Are you using a 3 phase transformer? 3 phase transformers are wye-delta, delta-wye et. for motors, usually for changing speed. A single phase transformer doesn't have the center tap. If using a single phase transformer, the configuration is consistent. Use Ohm's Law to determine primary/secondary amps.

2.5KVA = 2500 VA
(volts X amps + VA) so...
2500 / 240 = 10.416 amps on the secondary
2500 / 575 = 4.347 amps for the primary

On a 2:1 ratio transformer, you just half the secondary amps for the primary (480V to 240V). On a 4:1, it works out to 1/4 of the secondary.

stasis I will be using a 3 phase step down transformer to go from 575Vac 3phase to 240Vac 3phase @2.5KVA required to run the Torque tools.
Yes PE = Ground, But I am still not sure as of which configuration should I go for wye-wye, delta-wye, wye-delta, or delta-delta.

Thank you again,
Y@S!

I'm not sure what you are connecting as far as load demand, and that in itself would determine which connection type you would need. Have a look at this link & see if it helps...

http://www.elec-toolbox.com/usefulinfo/xfmr-3ph.htm

well you are pretty much buggered to get anything of the shelf..However you should go with a 600v delta to 240v 3phase Y config..I honestly havnt used a Wye-Wye transformer..On 3 phase why would you?..

Now re reading you post you never specificaly said 3 phase 240v (this is uncommon in Canada..we usualy use 240v single phase)..The only machines i have hooked up here using 240v 3 phase were made by a European company..And we had to go with 3 phase delta..

Where abouts in Canada r u?

D

This is the UGLY book stasis refered too, most electrical suppliers carry them..in many cases they will give you one. They were around $5 US when I got mine but the 2005 version appears to cost $14-15 US.
http://store.yahoo.com/contractorslibrary/ugelrere20ed.html

This is the ACME transformer site, it has alot of information and wiring info.
http://www.acmepowerdist.com/tech.html

http://www.acmepowerdist.com/pdf/Page%2055-63.pdf

Forget the stuff about transformers and single phase...ie they can be single or 3 phase.

Delta to Delta (with a neutral) means that if you input 600 volts and get 240vac phase to phase out but you will have 2 legs that offer 120vac to neutral...the third phase (leg) is called a wild leg, the neutral is just common to 2 phases.

Delta to Delta (no neutral) will offer 3 phase with 240vac between the 3 phases...no 120vac

Delta to Wye offers 208vac phase to phase and 120vac phase to neutral...for all three phases.

This is a simple overview but should get you started.

rsdoran said:

This is the UGLY book stasis refered too, most electrical suppliers carry them..in many cases they will give you one. They were around $5 US when I got mine but the 2005 version appears to cost $14-15 US.
http://store.yahoo.com/contractorslibrary/ugelrere20ed.html

This is the ACME transformer site, it has alot of information and wiring info.
http://www.acmepowerdist.com/tech.html

http://www.acmepowerdist.com/pdf/Page%2055-63.pdf

Forget the stuff about transformers and single phase...ie they can be single or 3 phase.

Delta to Delta (with a neutral) means that if you input 600 volts and get 240vac phase to phase out but you will have 2 legs that offer 120vac to neutral...the third phase (leg) is called a wild leg, the neutral is just common to 2 phases.

Delta to Delta (no neutral) will offer 3 phase with 240vac between the 3 phases...no 120vac

Delta to Wye offers 208vac phase to phase and 120vac phase to neutral...for all three phases.

This is a simple overview but should get you started.

Click to expand...

Ron... I never ran across a delta to delta (with a neutral)..how do they do this? Is it just refernced to ground? how do they bond it? How do they generate the neutral? This might shed some light on why i had to use the delta to delta on the 240v machines..

Thanks

D

In this thread I show a picture of a Delta secondary with a neutral. The neutral is center tapped (bonded to ground) from one of the windings so it provides 120vac between 2 phase and 208vac neutral to the third phase. 240vac phase to phase.
http://www.plctalk.net/qanda/showthread.php?postid=66938#post66938

I am a little unclear of where you bonded..From the diagram it looks like the middle of the winding..how do you do that?