Previous in Forum: Fast-Opening Air Break Contactor   Next in Forum: circuit breaker
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
18 comments
Rate Comments: Nested
Anonymous Poster

Single Phase and Phase-to-Phase Voltage

02/11/2009 3:29 AM

Hi,

We have a controller which mentions that 210~230V Single phase (50 or 60Hz can be accepted by the controller) has to be its input power.

I presume that this could only mean 210~230V power to be wired between Line & Neutral.

But if the customer side have only 3 wire- delta type 440V -3ph supply without a neutral, how do I wire the input power to my controller?

Hope someone can clarify.
Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
atchet
Associate

Join Date: Feb 2009
Posts: 33
#1

Re: Single phase -Can I use phase-to-phase Volt

02/11/2009 3:34 AM

find a step down transformer
Reply
Anonymous Poster
#2
In reply to #1

Re: Single phase -Can I use phase-to-phase Volt

02/11/2009 4:17 AM

Hi,

Could you explain your reply in detail. Are you saying that we should take the 3 phase 440V supply feed to a transformer with secondary Y and then use that? Is that the only choice? It is a bit difficult at this stage practically.

Maybe I would re-phrase my query

- Is it possible to use say 230V - by connecting between Phase to Phase instead of connecting between Line to neutral?

- Do we term both phase-to-phase and also Line-to-neutral also as single phase?

Thank you
Reply
ozzb
Guru
Hobbies - Fishing - Old Salt Hobbies - CNC - New Member United States - US - Statue of Liberty - New Member

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5197
Good Answers: 266
#3
In reply to #2

Re: Single phase -Can I use phase-to-phase Volt

02/11/2009 7:12 AM

Phase to phase the voltage will be about 440. Phase to neutral will be about 260 V both will be to high for your controller. You will need a transformer to obtain the voltage. Unless you have 220 3ø that you can provide power to the equipment with?

__________________
 Life is not a journey to the grave with the intention of arriving in a pretty, pristine body but rather to come sliding in sideways, all used up and exclaiming, "Wow, what a ride!"
Reply
2
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#4

Re: Single phase -Can I use phase-to-phase Volt

02/11/2009 8:38 AM

The phase to phase in your case is 440V (that's what you have mentioned)

Since you need 220 V (assuming the average). Use a 2: 1 transformer.

Connect the pri across phase and on the secondary, preferably ground (earth) one of the terminals. It may not be advisable to have a floating neutral.

Before that measure the phase to phase voltage with a multimeter and that will satisfy you.

The phase to phase even if it comes anyway near your range is still not advisable since your equipment may not like voltage signals on both the leads (esp it's electronics) and still you will need an isolation transformer with secondary earthed.

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply Good Answer (Score 2)
No more Good Answers.
HoleInTheSnow
Power-User

Join Date: May 2008
Location: Europe
Posts: 285
Good Answers: 9
#13
In reply to #4

Re: Single phase -Can I use phase-to-phase Volt

02/12/2009 6:02 AM

GA from me.

Regards

Mr. W.A Snow
Reply Off Topic (Score 5)
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#14
In reply to #13

Re: Single phase -Can I use phase-to-phase Volt

02/12/2009 7:45 AM

Thanks I should but gremlins don't they

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply Off Topic (Score 5)
wareagle
Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#5

Re: Single Phase and Phase-to-Phase Voltage

02/11/2009 11:27 AM

Guest quote " Are you saying that we should take the 3 phase 440V supply feed to a transformer with secondary Y and then use that? Is that the only choice? It is a bit difficult at this stage practically.

Maybe I would re-phrase my query

- Is it possible to use say 230V - by connecting between Phase to Phase instead of connecting between Line to neutral?

- Do we term both phase-to-phase and also Line-to-neutral also as single phase?"

That the only choice. In a delta system you do not have a neutral connection. Your voltage phase to phase is 440 volts. Take two of the phases, 440 volts, to a single 440/240/120 volt transformer. Size the transformer to your requirements.
Reply
Anonymous Poster
#6
In reply to #5

Re: Single Phase and Phase-to-Phase Voltage

02/11/2009 7:21 PM

Thanks for all your comments & clarification.

a) If the client has 3ph 230V ( I am not sure whether they have a star or delta transformer) then if my controller requires single phase 230V, am I allowed to connect my controller between any of the two phases (say Ph1 and Ph 2). Still my controller gets a voltage of 230V AC.

b) What is the difference between such connection and between connecting it between a phase and neutral of a 400V Star secondary, which gives me a single phase 230V?

c) Are both the connections shown in above cases (ph- ph = 230V) and (Ph to Neutral = 230V) considered as single phase connections.

What is the difference essentially in such connections?
Reply
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#7
In reply to #6

Re: Single Phase and Phase-to-Phase Voltage

02/11/2009 9:17 PM

3 phase 230V ?

Again let me repeat- a lot of electronics equipments do not like floating neutral (ie the neutral voltage greater than a particular value) f course you might have a isolation transformer inside, then it won't matter.

But otherwise you will damage your equipment since ph-ph connection means the neutral is at 115V

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply
Anonymous Poster
#8
In reply to #7

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 12:33 AM

Thanks a lot SB. Pls check if my understanding is correct.

Case 1: Ph - ph voltage given is 230V AC.

I should connect the single phase isolation transformer's (ratio 1:1) primary to this 230V AC - phase to phase.

Then I should use this secondary leads to connect to my controller's input of Line and Neutral, requiring 230V AC single phase. ( The secondary lead which is connected to the neutral should also be grournded or earther).

Is this correct?

Case 2: Ph - ph voltage given is 400V AC.

I should connect the single phase isolation transformer's (ratio 400:230) primary to this 400V AC - phase to phase.

Then I should use this secondary leads to connect to my controller's input of Line and Neutral, requiring 230V AC single phase. ( The secondary lead which is connected to the neutral should also be grournded or earther).

Is this correct?

Pls re-confirm. Thanks again.
Reply
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#9
In reply to #8

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 2:13 AM

(no smiley for thumbs up)

Miss lot of them.

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply
Anonymous Poster
#11
In reply to #9

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 3:12 AM

Does it mean that that my understanding is correct?
Reply
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#12
In reply to #11

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 3:59 AM

Thumbs up means it.

Other portion (missing smiley is Offtopic)

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply Off Topic (Score 5)
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#10
In reply to #8

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 2:46 AM

PS: the isolation transformer is required if you don't have already one inside your controller circuit.

If you have doubt, no loss in having an extra (only loss may be a few $- the few depends on the KVA)

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply
Anonymous Poster
#15

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 6:03 PM

CALL AN ELECTRICIAN ( One who is Qualified to work with electricity ) before you hurt yourself!!
Reply
sb
Guru

Join Date: Mar 2007
Posts: 2550
Good Answers: 103
#16

Re: Single Phase and Phase-to-Phase Voltage

02/12/2009 9:18 PM

he is the supplier of controller hence must know electricity. Only he has some problem with supply conditions.

__________________
 Fantastic ideas for a Fantastic World, I make the illogical logical.They put me in cars,they put me in yer tv.They put me in stereos and those little radios you stick in your ears.They even put me in watches, they have teeny gremlins for your watches
Reply
Anonymous Poster
#17
In reply to #16

Re: Single Phase and Phase-to-Phase Voltage

02/13/2009 8:44 PM

Obviously not true, or he would not have problems with such a simple matter.
Reply
Anonymous Poster
#18

Re: Single Phase and Phase-to-Phase Voltage

02/15/2009 9:01 PM

In reply to 17:

Hi Guest,

From your reply you seem to be a person with immense knowledge but not willing to help. So why do you bother even checking such forums.

In reply to SB's clarification.

Hi SB,

Your effort is well appreciated.

Thanks a lot.
Reply Off Topic (Score 5)
Reply to Forum Thread
Have a Different Question?
18 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (7); atchet (1); HoleInTheSnow (1); ozzb (1); sb (7); wareagle (1)

Previous in Forum: Fast-Opening Air Break Contactor   Next in Forum: circuit breaker

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (74 right now)
Show Members
Advertisement