When is Neutral Isolation Required?

Thanks for the "to the point reply".

But ar there any other implications rather than Commercial if we use 4P for both Incomer and Bus Coupler

Regards

Abhijit

No! Rather, it is much safer to have 4-pole at both Incomers & the bus coupler. But, aren't good engineers good economists too?

Thanks a lot

Hope our interaction on Electrical Engineering Continues

Regards

Abhijit

Saluting you sir.....very nice explanation.....I had wondered why the buscoupler hav 4 poles......especially given in L&T made PCCs........

Thanks for the compliments! I have also been enjoying your postings in the forum. At this instant, I would like to reiterate that even though I work for L & T, I am not a product marketing person. I only try to explain concepts.

Thank you.....If I could ask can you tell me what are you into in L & T ...how you really get time to reply/opine to the numerous postings in this forum.........But there was no answer to my question in the thread "transformer differential protection".pls reply.

i) I am a Manager-Training with L & T at their Switchgear Training Centre at Coonoor near Ooty in Tamilnadu.

ii) I have a internet connection at home. I am sort of addicted to this forum. And, I sincerely enjoy interacting in the forum. I will not rest for the day unless and until I visit this forum and answer a few questions. Thanks to participants like you.

iii) I have just now answered your query on Transforemr Differential Protection. Please go thro the same and let me have your views on that.

GOOD.......but your knowledge is of high level,to be frank.......keep it up man!

Iam working in petrochemicals/refinery industry as an electrical maintenance engineer for the past 3 years.....

Dear sir,

3pole or 4pole switches are used in changing over two independant sources ,where the neutral of one ssource and the neutral of another source should notmix,.the examples are electricity board power supply and standalone generator supply etc. the neutral return current from one source should not mix with or return to another source.

as a mandatory point the neutral of any trabsformer etc are to be earthed,similarly the neutral of a generator also has to be earthed.While paralling (under ubcontrolled condition) the neutral current between the 2 sources will criss cross and create tripping of anyone source breacker.

also as per IECstandard the neutral of a distribution system shall not be earthed more than once.means earthing the neutral further downstream is not correct,

However there are certain conditions under which theAUTOTRANSFER SWITCHES WORKS.The voltage,phase rotation frequency are o be matched for closed loop trancfer. Furthe if interested call"loganathan52@gmail.com"

In field practice, in any application on electrical system, neutral needs to be insulated to avoid in contacts or accidental contact in metal parts of the electrical equipement since metal frames are bonded to the grounding sytem. Leakage current current will flow to the path of earthing system will cause a " ground or earth fault current" might harm the working personnel and may even trigger the electrical sparks.

But the question is Neutral Isolation and not neutral insulation.

The <...neutral...> conductor is current-carrying. Therefore whenever a device is being used for isolation for the purposes of ensuring safety, various standards require it to happen.

It certainly appears in British Standard 7671, for example.