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Non-Standard Transformer

12/14/2007 7:33 AM

We have got a Chinese l- sealer. It has a transformer of 240v/ 54v, single phase. Need to know anyone have the ready made transformer meeting this capacity.

Much specifications are not know as seems to be Chinese. Specs are written in Chinese.

Though we are trying to rewind locally but this takes time and also found the core to be damaged.

Anyone having details of vendor who can supply this very fast.

Shivaram

+91-80-9845756340

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Guru
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#1

Re: Non-Standard Transformer

12/14/2007 8:57 AM

Hope you know at least the VA rating of the transformer ,then get a dimmer-stat readily available with AE ( Automatic Electric )dealer and set its output at 54 volts and seal it and connect to your load and solve your problem immediately.Their telephone number is 91-80-22242095. Later you can order one from National Controlling Equipments Industries Haryana. Contact details nacei@rediffmail.com They make non standard transformers on specific order. There may be some manufacturers in Bangalore itself who can supply it.

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#6
In reply to #1

Re: Non-Standard Transformer

12/16/2007 5:48 AM

Unsafe, most dimmers do not isolate and the waveform is rarely a sine wave either.

Could kill someone with this proposal or burn the equipment...

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Guru
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#11
In reply to #6

Re: Non-Standard Transformer

12/17/2007 3:49 PM

Andy Germany ,

The AE make Dimmer stat is an auto transformer.( Probably the terminology used may be confused to be inverter)There is no danger in using auto transformer in place of isolation transformer so long as the system is properly earthed and there is no specific requirement for primary secondary isolation functionally.Probably you might have taken it to be an electronic inverter. There is no frequency change in auto transformer. We always use auto transformer when transformers with odd voltage ratio fail and immediate replacement is not available. In 40 years of my experience I have used it in many occasions and have never come across any accident in using auto transformer to replace isolation transformer when damaged.

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#13
In reply to #11

Re: Non-Standard Transformer

12/18/2007 3:59 AM

I hate to say this, but I feel that you have had great luck in not killing anyone if what you say is true about the way you have used autotransformers during the last 40 years!.

An autotransformer does NOT isolate the input mains from the output. But provided safety precautions are fully taken care of on the secondary side, this danger can be avoided, but as many inexperienced people read CR4, I have to make sure that they are not put under a false impression of safety from your words regarding autotransformer.....sorry!!!

You may know what you are doing and when, but they cannot learn from you safety when you do not cover it fully.....I will attempt to correct that here and now.

Here is a simple drawing of a normal Autotransformer taken from Wikipedia, is this the transformer that you were were referring to?:-

As you can see, the primary input and the secondary outputs are directly connected with each other via the single transformer coil in one case and directly with the other.....inductance but little resistance....

The whole link may be found at:-

http://en.wikipedia.org/wiki/Autotransformer

Autotransformers must ONLY be used where the secondary output is treated and insulated/isolated as though it was the mains connection itself.

If you read through the Wiki article fully it mentions this point:-

Limitations

A failure of the insulation or the windings of an autotransformer can result in full input voltage to be applied to the output. This is an important safety consideration when deciding to use an autotransfomer in a given application.

It does not even mention the fact that the "straight through" connection needs to be connected to the Neutral, not phase, but in countries where there is no definition of neutral or phase (USA & Europe, but not the UK for example) this can happen....Really really dangerous indeed.....

Maybe you are mixing up another transformer type with Auto transformer, which would explain the errors/misunderstandings you have made. Please explain where we have misunderstood your comments if that is true....but a normal (as shown above) Atotransformer is a really dangerous beast for anyone who does not understand its quirks......hopefully you do and only your explanation was not fully correct!

Happy Christmas.

Just because no accidents have happened, does not mean that a potential hazard is not there.....driving on the left hand side of the road in the US and Europe, only causes an accident when someone comes from the opposite direction!!! Possibly!!

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Guru
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#14
In reply to #13

Re: Non-Standard Transformer

12/19/2007 3:58 AM

Andy Germany : When the full plant stops working and production come to stand still as a maintenance manager you have to ensure that the machine restart immediately. The use of auto transformer as a make shift temporary arrangement become essential when immediate replacement is not available. Theoretically it look is a bit unsafe but with proper protective system and proper safety checks after considering the operational safety in the specific cases .By experience you can asses it and the arrange met works safely with out any accident. It is not simple luck that no accident happened but the proper checks and arrangements and the caution given to staff concerned make it work.If you don't take such minor risks you will be out of job.Such arrangements are not permanent but for a day or two till your original transformer is replaced.

Merry Christmas

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#15
In reply to #14

Re: Non-Standard Transformer

12/19/2007 4:39 AM

You did not mention safety before, that was your failure, which is why I did.

Also minor risks are for your place of work (maybe!), not for CR4 and possibly people reading it who have little or no idea of anything to do with electricity....you are in front of the class, you are a teacher....on CR4 at least.

A 50% correct answer only puts you at the bottom of the class, try to remember this and post 100% correct answers the next time, then you won't be criticized when someone like myself pops up and adds what you forgot......and someone always will. If you can't take it, go away......

Also, think about this, if you had just thanked me for my help in completing your answer, it would have looked as though we were working together to give a complete answer, which in fact was my aim.....but no, you feel ATTACKED and you aim your gun back at me for your errors!!!!

SAFETY IS PARAMOUNT ON CR4!!!! YOU WILL ALWAYS BE CRITICIZED FOR NOT HANDLING SAFETY FULLY AND CORRECTLY IN YOUR POSTS AT ALL TIMES, and not just by me.

If it is any consolation, there are a few other UN-safety conscious people here too.......

So which one of us reacts the best in such situations? I think that the answer is obvious to all concerned.....

Try and grow up in your attitudes, it will help you in all areas of life, not just on CR4......!!! Learn to understand where you also need to learn......and don't fight back when you have made a failure, accept and learn from it....

Crappy Isthmus!

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Power-User

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#8
In reply to #1

Re: Non-Standard Transformer

12/16/2007 11:41 PM

I agree with #6 This is a very unsafe recommendation. Injury or electrocution could result.

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#2

Re: Non-Standard Transformer

12/14/2007 11:01 AM

Block make a range of transformers with lots of link combinations for varying the turns ratio. If you go to the RS site and look up order code 419-7439, you'll find a 250VA one designed for 2 x 0-115V outputs with a range of input voltages from 208 to 600.

If you work the sums, you can get 53V out for 240V in by linking terminals 31-35 and wiring the outputs in parallel. Since (I assume) you're only working with a nominal 240V (and you haven't mentioned regulation), this should be near enough!

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Power-User

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#3

Re: Non-Standard Transformer

12/15/2007 12:03 AM

Automatci electricals don't have in stock. It is mostly " Order to make" type and takes minimum 25 days to depatch. RS is in contact if thye have in ready stock.

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#4
In reply to #3

Re: Non-Standard Transformer

12/15/2007 3:21 AM

Any Idea how big is your damaged transformer ( VA ) ? If You can find out the capacity and dimensions of the transformer it may be possible to find availability.AE Bombay office may be able to help you. If you are not able to locate mail me can try to help you.

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#5

Re: Non-Standard Transformer

12/15/2007 8:08 AM

Depending on the required current, you might use a Variac (variable transformer), and set the output voltage to 54 volts until you find a suitable replacement for your defective transformer.

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#7
In reply to #5

Re: Non-Standard Transformer

12/16/2007 5:49 AM

Only if it is of a type with an isolated output, otherwise far too dangerous.....

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#9
In reply to #7

Re: Non-Standard Transformer

12/17/2007 8:40 AM

If the electric heating element is safer when powered by a floating supply, then obtain the correct transformer or use the variac or the lamp dimmer through an isolation transformer. Resistance heaters generally don't care whether they are powered by pure sine waves.

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#10
In reply to #9

Re: Non-Standard Transformer

12/17/2007 9:56 AM

...and what if it has a PIC or similar controller inside? Then it might get some real problems as sometimes the mains is used as a slow clock for cheapness.....

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#12

Re: Non-Standard Transformer

12/18/2007 12:19 AM

we have got it repaired locally. I would like to get and keep one a spare. Also in talks with RS.

Thanks to all for their support and response.

Shivaram

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