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Lead Acid Battery Charging

11/05/2010 4:15 AM

WE have 400V AC 3 phase supply. We need to have several 380V DC Battery Charginging Circuits each of 50A,DC. One Panel to have 4 such circuits. Can we avoid the transformer totally since difference in peak voltages is low? With removal of transformer, will the energy efficiency improve? With 6 pulse SCR circuits what protection is needed ? What are other possibilities, so that transformer is avoided in the panel. Charging DC voltage can varry from 300V DC to 380V DC. Possibility of short circuit is there and also programmed stepped charging including discharge back to mains.

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Guru
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#1

Re: Lead Acid Battery Charging

11/05/2010 8:28 AM

It depends upon whether the DC system is needed to be galvanically isolated from the incoming mains. It wouldn't do for someone to touch the +380VDC and get killed, would it?

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#2
In reply to #1

Re: Lead Acid Battery Charging

11/05/2010 5:12 PM

No, he will not get killed but the +380VDC work's martyr !

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Guru
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#3
In reply to #1

Re: Lead Acid Battery Charging

11/05/2010 11:34 PM

Floating power source is much better. Transformer, rectifier and current limiting / current control circuit along with charged condition detection circuit to be installed for a proper system. All this engineering work is already developed one so why act in ancient way once again?

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#27
In reply to #3

Re: Lead Acid Battery Charging

11/08/2010 9:38 AM

Quite.

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Guru

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#4

Re: Lead Acid Battery Charging

11/06/2010 12:35 AM

I am working in Battery Mfg co. I have more than 6000 chargers-cur-regenerative-discharges mentioned by you. Having a transformer is for operator safety. Yes, it is possible to avoid transformers in chargers and increase efficiency; at the same time ensuring full safety to operators; this needs greater thinking and some research work. I do have some ideas but not able to disclose in this forum; sorry for that!

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#5
In reply to #4

Re: Lead Acid Battery Charging

11/06/2010 2:57 AM

How about using different hardware like IGBT which has very fast response time ,to take care of safety issues ?

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Guru

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#6
In reply to #5

Re: Lead Acid Battery Charging

11/06/2010 4:55 AM

Only two types possible are SCR & IGBT versions. SCR version (max. 88% efficiency) can be charger/ discharger but IGBT will be only charger. Our company once manufactured SMPS chargers up to 15V200A but such high current designs in India are not successful. I have worked on IGBT based (Isreal) 1MHz SMPS power supply of 15V100A which is very portable but such speciality magentics are not available in india. I have worked for quite some time to designing DC bus based charger/ dischargers that are will be above 95% efficiency but stopped working on that due to lack of support and encouragement. Still my dreams are alive...thank God!

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#8
In reply to #6

Re: Lead Acid Battery Charging

11/06/2010 1:44 PM

This post was deleted because it was overly religious or political. While each user is entitled to his or her own opinion on these topics, CR4 is not the place for discussion about them. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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Guru

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#9
In reply to #8

Re: Lead Acid Battery Charging

11/06/2010 3:19 PM

Dear Mullah,

Are you suggesting that the rest of the world quit sharing any technology with all Muslims out of respect for your beliefs? Can't have it both ways, and this forum is a marvelous lesson in overcoming such damaging prejudices.

Marvelous things get accomplished when people are not bounded by the boundaries you are implying should be in place.

We welcome you to this forum with it's wealth of sharing freely with one another without regard to who you are, but please note that divisive suggestions such as yours are the opposite of what this forum values, and will generally be considered ignorant and usually will be completely ignored.

Please understand that I am being informative not judgemental, and wish you a very positive experience and encourage you to share of your technical expertise or ask technical questions.

We also tend to have a great deal of fun, and interject humorous responses often, but please understand that it is never meant to offend. Enjoy.

Regards CJM

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#10
In reply to #9

Re: Lead Acid Battery Charging

11/06/2010 5:25 PM

CR4 ADMIN: Deleted Post

Politics/Religion: This post was deleted because it was overly religious or political. While each user is entitled to his or her own opinion on these topics, CR4 is not the place for discussion about them. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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Guru

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#11
In reply to #10

Re: Lead Acid Battery Charging

11/06/2010 6:57 PM

maybe you should share what Allah says because I cannot see where he said anything about the subject at hand.

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Guru

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#12
In reply to #10

Re: Lead Acid Battery Charging

11/06/2010 7:46 PM

Mullah,

This was, and still is, as far as I can find out, a forum for persons of all faiths,colours ,creeds, to seek knowledge on technical matters, at the same time affording a little fun in the process.

If you should want to reduce it to religious mudslinging, I shall seek to have you removed by the admin.

Or I shall remove myself.

I'll not be a party to such endeavours in what has been thus far a very enjoyable experience for the participants.

A previous poster said it all. You are most welcome to our 'home'. But you have to observe our rules, just the same as we would observe your rules in your home.

In peace,

Cheers,

Stu.

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#13
In reply to #12

Re: Lead Acid Battery Charging

11/06/2010 8:33 PM

CR4 ADMIN: Deleted Post

Politics/Religion: This post was deleted because it was overly religious or political. While each user is entitled to his or her own opinion on these topics, CR4 is not the place for discussion about them. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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#14
In reply to #13

Re: Lead Acid Battery Charging

11/06/2010 8:49 PM

CR4 ADMIN: Deleted Post

Politics/Religion: This post was deleted because it was overly religious or political. While each user is entitled to his or her own opinion on these topics, CR4 is not the place for discussion about them. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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Guru

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#15
In reply to #13

Re: Lead Acid Battery Charging

11/06/2010 9:53 PM

CR4 ADMIN: Deleted Post

Politics/Religion: This post was deleted because it was overly religious or political. While each user is entitled to his or her own opinion on these topics, CR4 is not the place for discussion about them. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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#16
In reply to #15

Re: Lead Acid Battery Charging

11/06/2010 10:49 PM

CR4 ADMIN: Deleted Post

Politics/Religion: This post was deleted because it was overly religious or political. While each user is entitled to his or her own opinion on these topics, CR4 is not the place for discussion about them. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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Guru
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#17
In reply to #9

Re: Lead Acid Battery Charging

11/06/2010 11:48 PM

Remain focused on engineering problems. Better to remove not relevant comments from CR4.

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Anonymous Poster
#21
In reply to #9

Re: Lead Acid Battery Charging

11/07/2010 5:51 PM

Where from you write your statement,from Isreal ?

We do not believe your falsely lying.

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Guru

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#22
In reply to #21

Re: Lead Acid Battery Charging

11/07/2010 10:01 PM

Dear Guest,

My friendly advice to help the mullah to be welcome on this world-wide forum was ignored, and the result is a series of comments being deleted by the forum managers.

Believe it or don't believe it, you must admit that political and religious prejudices are deleted soon after they appear here regardless of the source.

I personally have no vested interest in either side of the issues raised by the mullah. I also have registered on this forum, with my location information. I do not hide behind the title 'Guest', and I do not refer to myself as 'we'.

I now offer to you the same heartfelt advice: In order for you to enjoy the opportunity to participate here you must refrain from posting religious or political comments.

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#25
In reply to #22

Re: Lead Acid Battery Charging

11/08/2010 7:40 AM

No question,you are Israeli lives in USA and as usual practicing your normal deception.

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Guru
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#28
In reply to #22

Re: Lead Acid Battery Charging

11/08/2010 10:42 AM

and it is for good. This forum has been good except for few utter poor entries. I greatly appreciate the quality of normal discussions and they are pretty interesting one. People here are very helpful. There are bad fish entries that make pool a bit dirty, and some cleaning work is always better.

President Mr. Barack Obama is in India and presence of first USA family is making all headlines in homes. I think USA is a dreamland for many. For me India is the greatest as my people are here near me. All of us should make their own countries worth living at least for ourselves by educating.

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Guru

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#29
In reply to #28

Re: Lead Acid Battery Charging

11/08/2010 4:45 PM

For what it's worth, I think you're right.

Stu.

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Guru
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#19
In reply to #6

Re: Lead Acid Battery Charging

11/07/2010 12:01 AM

I am actually looking for high frequency 500W to 1000W switching transformers for power drivers in 25kHz to 50kHz frequency range ultrasonic transducers 1:10 100V to 1000V step up voltage types. Any reference? I knew few companies in Israel had very innovative transformer designs in this frequency range and high power. These will also be helpful in MOSFET / IGBT chargers giving nearly stable charging current.

Perhaps your experience in magnetics is valuable so do some work in this area in India and it is Ok to import those transformers from Israel or from anywhere.

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#23
In reply to #19

Re: Lead Acid Battery Charging

11/08/2010 4:57 AM

25KHz to 50KHz most computer SMPS transformers can serve your purpose. Try this web site: www.smps.us/ ; I have used discarded PC SMPS to build new power supplies.

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Guru
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#24
In reply to #23

Re: Lead Acid Battery Charging

11/08/2010 6:46 AM

Do you get 1kW SMPS for PC? Also these must be step down transformers. I need step up type at least a factor of 3 or 1:3 ratio step up to 1000V output at 25kHz 1A average current.

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#31
In reply to #24

Re: Lead Acid Battery Charging

11/08/2010 10:47 PM

Normal PC SMPS are up to 500VA. So you can use two transformer in parallel. Most modern PC-SMPS use about 60KHz. If you slightly increase switching frequency (say 75KHz) you can get 1200VA. Please go through the smps.us web site; there few good circuits available; ----kvsubramanyam

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Guru
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#32
In reply to #31

Re: Lead Acid Battery Charging

11/08/2010 10:59 PM

any manufacturer's brand name for these transformers? where I can purchase a reliable one?

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#33
In reply to #32

Re: Lead Acid Battery Charging

11/09/2010 4:55 AM

Most available are Chinese make. I get at Hyderabad local market. In Electronics For You magazine you can find many suppliers....kvsubramanyam

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Anonymous Poster
#30
In reply to #19

Re: Lead Acid Battery Charging

11/08/2010 6:17 PM

That is your choice , it doesn't concern me,try to depend on your self rather to ask so many questions

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Guru

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#7

Re: Lead Acid Battery Charging

11/06/2010 9:36 AM

Transformers are VERY efficient. A transformer will allow you to tailor your battery charging systems, allowing you to have versatility. This versatility will allow better efficiencies in the future.

I don't think your electrical code will allow you to run an industrial system without some sort of isolating transformer.

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Guru
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#18
In reply to #7

Re: Lead Acid Battery Charging

11/06/2010 11:53 PM

Sometime to reduce cost, people do use auto-transformer in charger. However isolated version is much better.

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Anonymous Poster
#20

Re: Lead Acid Battery Charging

11/07/2010 1:57 AM

380 V DC battery charging circuit at 50 A is 19 kW DC, 4 such circuits in a panel is 76 kW DC. At 85% efficiency, this is equal to 89.4 kW & at 0.8 pf this is 111.76 kVA. This is quite a bit of power & so, on safety grounds, I will not suggest transformerless design.

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Power-User

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#26
In reply to #20

Re: Lead Acid Battery Charging

11/08/2010 9:07 AM

Thanks for the reply. The point I raised , that we are loosing some efficiency because of use of transformer for safety reason. Can the safety feture required be addressed by any other means which does nor need transformer and is more efficient? If capacity is constraint, then to what level we can go ?

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