High voltage resistor 3 phase 5

[machmech]

Hello Folks

Recently we received an Envelope machine from Poland and are in the process of rebuilding it for production in our plant.

The Plant manager and contracted electricians are going to install two transformers for the following reasons.
1.The feed is 480 v
2.The motor and AC drive need 380 v
3.The control panel needs 208 v

My question - Are there other ways to step down to 208 v 3 phase from 380 v? Possibly some sort of resistor or voltage divider product. I'm looking to save money, the cost of second auto x-former.

Chuck

 

[CJCPE]

Before buying a 480:380 transformer check carefully to make sure the drive can't be adjusted to accept 480V input and provide 380V output. Many can.

 

[CJCPE]

Resistors are occasionally used to supply reduced voltage to very small unchanging loads like pilot lights, they are rarely suitable in any other situation. You are going to need an autotransformer for the 208V, 3-ph load.

 

[rbulsara]

Whats wrong with using standard 480V:208V control transformer? Single phase or Three phase. They are off-the- shelf items and cheap.

I think the plant manager is on the right track.

 

[aolalde]

If your facility is in America, I think your mayor problem is frequency, a lot of European countries use 50 HZ. Unless all motors are DC, the frequency will change the performance of induction motors and most important, the speed will increase with 60 HZ. The speed increase will traduce in more power demand to the motors and possible damage on some mechanical elements of the machine. Check with detail if this is your case.

 

[LionelHutz]

Look at what CJCPE posted again. This could save on the large transformer and correct the 50hz/60hz issue if it exists.

Many control components can run on either frequency. With magnetics, increase the voltage at 60hz by 20% compared to the 50hz voltage to maintain the same V/hz ratio.

A Y connected transformer would get you 380V L-L and 220V L-N and could run the whole thing.

 

[jraef]

Hi machmech,
All good answers. To recap and clarify:

1) We are assuming that by using the word "drive" you are meaning a VFD. Post the nameplate details of that VFD, it is most likely that the VFD can accept 480V input without a transformer. Most VFDs are built in 2 "Classes", a 200V Class which can accept anywhere from 200 - 250V AC input, and a 400V Class which can accept anywhere from 380 - 480V input (there are higher classes but those are irrelevant here).

2) Post your motor nameplate details. If the VFD can accept 480V, you still must make sure that the VFD output matches the motor nameplate. The output can always be lower than the input voltage, but the current must be within range too.

3) Double check your control power's requirements for 208V. That is NOT a standard for European voltage systems, in fact several websites list Poland as using 220V 50Hz as a control voltage standard. 208V may in fact be the lower limit of what they need, so it would not be prudent to specifically target the lower limit. A standard 480-240V transformer may be a better choice. No matter what, step your control panel power requirements down from the 480V side, which will not be a problem if the VFD can accept 480V.

4) Speaking of which, you didn't say if the "control panel" needs 1 phase or 3 phase. If it is just controls such as relays, timers, PLCs etc., then I would think 1 phase. If it controls other motors, then it may need 3 phase. That would be a big difference in the transformer, and the motor issue raises more questions.

5) Double check the internal components of your control panel for suitability to operates at 60Hz (assuming that because of 480V). Many 50Hz designed coil operated devices such as relays and contactors as well as clock motor timers cannot have 60Hz applied to them without consequence. You may need to change out those devices.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[machmech]

Hello jraef

I apologize for not responding sooner, I went to work today armed with ideas from previous post and talked to everyone involved.

Yes I do mean VFD, The following is all the info we have no manual was included.

Danfoss VLT 5000
IN-2x380-500 v 50/60 A 43.3
Out-3x0 Vin 0-1000 Hz
cn175z4123
s/n:0121176509

The electrician has little knowledge on how drives work and I have even less, We looked inside and don't understand how it would accept a higher voltage then lower it without a transformer to do this. With the info we have our thoughts are the motor will see what the input sees. I am going to do some googling to understand how these things work. Our Plant Manager is trying to locate a manual I will do the same after I'm done here.

I am at home now and do not have motor data but remember it was 50Hz only made in Poland and needs to see 380 v. Thanks to itsmoked composing the FAQ on 50/60 Hz I think we will be OK with 20% speed increase and will take amp reading at start up.

The control cabinet was hooked up 208 three phase, We have several small 3 phase motors operating from here. This is why the idea from Lionelhutz will not work, They actually sent us the Tranformator (not a typo!) and this darn thing looks like it was hooked up to 600 v !! but were not sure due to language on data plate. Once again our guess is primary 600 v secondary 380/208. The Plant Manager purchased the machine and has limited knowledge of electricity, He only checked things out mechanically and did not ask about connections. It looks like most of controls will operate on 380 50/60 Hz but the electrician does not want to risk it.

Currently we have a 480 to 380 transformer at machine for drive and motor, and an auto transformer is planed to be installed for 208 v, It cost $1,850 and will be mounted on top of panel, kind of a goofy set up. Would be nice to avoid this cost.

I do believe your idea of changing out a few items is good compared to spending that money on the second transformer.

Thanks for all the replies, I will keep my eyes glued for any further ideas.

Chuck

 

[jraef]

You do NOT need the transformer for the drive, it can accept any input source up to 500V AC. VFDs work by converting the incoming AC power into DC, then "recreating" a simulated AC output with transistors, called inverting. Since the input is essentially just a "raw material" for the inverter and the output is wholly manufactured by the VFD, it can be made to be anything you want it to be, up to and including the incoming line voltage and anywhere below that. So your VFD is probably already set up by the factory to provide the proper 380V 50Hz output, you may not need to do anything else to it. Just so you know, using VFDs is often a simplified method of dealing with the different voltages around the world for OEM machine manufacturers.

So on to your 208V control panel. I still find it hard to believe that a Polish OEM would design a panel for 208V 3 phase, it makes no sense. Be that as it may, what you want now then is a 480-208V 3 phase transformer. These are VERY common and inexpensive. Forget the transformer they sent you, it makes no sense. Forget the autotransformer as well, it may not give you what you want.

Being that you and your electrician and Plant Manager are so unfamiliar with this, I would strongly suggest that you hire someone with expertise in this field to have them evaluate all of the issues at hand. There are too many potential pitfalls ahead for you to navigate solely via a web forum and Google IMHO. Look in your area for a control panel shop and find one that has experience in IEC-to-UL panel conversion. It will undoubtedly cost you less in the long run.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[machmech]

That is some awesome technology in a small package then, I will meet with everyone first thing and recommend your suggestions be followed and see what they think.

Tomorrow I will copy data plate info on transformer made in Poland and post it to see if anyone understands and can confirm its function.

Thanks for some great advice!

Chuck

 

[CJCPE]

Regarding the info you have on the VLT 5000:

"IN-2x380-500 v 50/60 A 43.3"

Are you sure that is not "IN-3?" I think "IN-2" would indicate two input terminals -- single phase input. "380-500 v" indicates that the rated input voltage range is 380 to 500 volts. "50/60" indicates the unit is rated for 50 or 60 hz. "A 43.3" is probably the current rating. Input and output current ratings are probably the same.

"Out-3x0 Vin 0-1000 Hz"

"Out-3x" indicates 3 output terminals -- 3 phase. "0 Vin" indicates that the maximum output voltage range is O to the connected input voltage. "0-1000 Hz" indicates that the maximum output frequency range is 0 to 1000 Hz.

"cn175z4123" seems to be the catalog number. I couldn't find a listing on the Danfoss web site, but it may be there someplace.

"s/n:0121176509" must be the serial number.

You should be able to find a downloadable manual at:

http://www.comcom.com/pz2/dnf/DanfossSearchOnly.jsp

Search for the exact phrase: "VLT 5000 IM" including the spaces. I couldn't figure out how to link directly to the manual.

It looks to me like you don't have to tell the unit what voltage it will be connected to. You should be able to connect it to 480V. 3-ph and run it without adjusting anything.

 

[ScottyUK]

Here's the link

http://www.comcom.com/pubzone/getFi...ble2/danfoss/G5351.349785.175R5271.4.TEXT.pdf

The file is 7 Meg - don't even consider it if you're on dialup!

----------------------------------

I don't suffer from insanity. I enjoy it...

 

[machmech]

Hello CJCPE

Nice catch, The correct digit is 3. If you are using Internet explorer going to this link may explain your problem on downloading.

http://compnetworking.about.com/cs/novellgroupwise/ht/setpassiveftpie.htm

After I responded to post I found Danfoss web site and was impressed they even offer software for free to communicate w/drives.

Thanks CJCPE and SkottyUK
Chuck

 

[machmech]

Hello jraef

I talked to the Plant Manager and Electrician again, A call was made by the Plant Manager to the tech support at Danfoss (The Drive manufacturer) and he confirmed what you said. The autotransformer for 380 has been cancelled,(I noticed I made a mistake and typed 208 v for autotransformer in previous post, 208 is installed already) A Controls Specialist will be in next week.

Got the data plate info off of Transformer made in Poland.

TYP TEa 100/0.5 Me NR 8813370 ROK 1988

MOC 100 KVA GR.Dyn5 PRACA C

GN 660-2.5/ v PRADZNAM 87.5 A

DN 400 v PRADZNAM 144.3 A

NAP.ZW. 3.19% LICZ. FAZ. 3 50Hz

STR.JAL. 477 w STR.OBC. 1100 w

ST. OCHR. IP-22 CHLODZ. AN-AN

TEMP. OT. 45 DEGREES-C PN-83/E-06040

MASA CALK. 575 kg KL. JZOL. B

POZIOMY IZOLACJI WTO-86/MIO-064

I know this thing is useless we would like to know if it was connected to 660 v.

Thanks Chuck

 

[Skogsgurra]

The GN 660 and DN 400 thing seems to imply that the primary is 660 V and the secondary is 400 V. The connection is three-phase Delta primary and Wye secondary, with Neutral available. Nominal power is 100 kVA. I shall get in touch with a Polish friend tomorrow and have him translate the other things. If needed. I think that there are some Polish guys over there.

Gunnar Englund

http://www.gke.org

 

[machmech]

Hello skogsgurra

660 v really made the sparkys scratch there head, they had a hard time believing it, and were curious.

As for the translation no need to labor it, this thing may get donated for local Charity's, copper is at a premium these days.

Thank you, Chuck

 

[Skogsgurra]

Why curious? The 660 V was a very common voltage level in Europe before changing to 690 V, which is common for larger drives.

Gunnar Englund

http://www.gke.org

 

[jraef]

Remember machmech, when you buy equipment from other parts of the world you have to let go of your American mindset on voltages etc. They do things funny over there ;-)

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[machmech]

LOL
Oh yes but those folks sure know how to make a great Beer.
I am glad I asked never knew how much they stated with,
We only see what the equipment needs, The electricians
joked about when those guy's make a mistake they don't
die they evaporate!

Chuck