For How Many Days Is It Safe For Power Xformer To Be Filled With Dry Nitrogen?

Why not ask the transformer manufacturer, whichever one it is? It is only a phone call, if the information is not already contained within the installation manual, after all.

It is a mystery. After all, the reason for not asking the manufacturer is completely abstruse, especially as there are sales warranty considerations to be considered before commercially-inapppropriate action takes place.

Manufacturer and its warranty, commercial aspect is one part, but now I need to know about the technical aspect behind filling dry nitrogen in transformer and its advantages as well as disadvantage.

Then pick up the phone and ask the principal source of information, which is the equipment manufacturer! No-one on the forum knows better than the original equipment manufacturer!

Th number of telephones on the planet has increased in proportion to the reciprocal of people's desire to use them for their original these days, it seems, especially as it is the quickest way of obtaining valid and appropriate information.

And "time is money" _{- Anon}.

It's people like you, who ask questions like this that have driven many members away!

ASK THE MANUFACTURER!

I'm pretty sure it not those who are asking questions, basic and obvious or otherwise, that drives members out.

It's the few A-hole members (largely the cowardly ones who have to post anonymously while being A-holes over largely stupid petty crap) that drives people out.

Amen to that! I say we vote the AP's out.

So this is you attempting to go against the advice of people more experienced and knowledgeable about power transformers, even the ones that manufacture them (OEM)?

From over here, it appears more like you attempting to make a donkey of yourself.

Why ask here or there if you have no ears to hear with?

What would the Supreme Being think?

The nitrogen in the transformer is good indefinitely, as long as the transformer is not connected, not energized in such condition. However, the sealing mechanism of said transformer is always in doubt. One must maintain a positive pressure of 99.999% nitrogen on the transformer during transport to new location, stationing, etc. A means must be provided to bleed the nitrogen gas away, possibly requiring the use of SF₆ gas as intermediate between the nitrogen and the following oil fill. The SF₆ gas must be re-captured, and not emitted to atmosphere.

If OEM gives you the go ahead with nitrogen only, then bleed down the nitrogen carefully, so that positive pressure is maintained while adding the oil slowly, to limit gas-oil interface area (slows down gas solubility), then monitor the oil-filled unit for an unspecified period of time to allow out-gassing of residual nitrogen.

The entire protocol is actually on you to establish and approve internally to your organization, but exercise care to not void the manufacturer's (OEM) warranty.

In these situations, given any conflicting information, protocols, etc., always choose the OEM protocol to follow to the letter, since that is the only one where you get paid when it fails to work. Your insurance carrier should also have a vote in this.

Nitrogen gas is non-reactive to the materials commonly found in transformers.

Thank you sir, for the clarification. In what instance would SF6 be used or required?

I have not known of it being used in transformers, since the nitrogen blanket works fine for keeping moisture and contaminants at bay while still being relatively inert and "harmless." SF6 is a great insulator, so it's generally used as electrical insulation in HV circuit breakers, GIS switchgear, etc. (where oil was used in years past), but not necessary for transformers. Its impact as a greenhouse gas is also detrimental to its use in transformers, where there often is a tendency for the gas blanket to leak away. This is based on my experience, not total knowledge across the industry - Others may have more to add to this topic...

Note too that some may have thought that SF6 would be a good insulating medium for transformers. However, it is not a good heat transfer material as is needed for cooling the windings, for which oil works much better. So mineral oil continues to be the most common insulating medium of choice for power transformers.

Thank you, sir, I do believe that clears up the matter in its entirety.

The insulation system must be known, and the solubility of the insulation with a gas could lead to trouble, if you have corona inducing high voltages present. The measures the factory uses to add the liquid dielectric, perhaps settling time and de-gassing time/procedures would be critical to establishing the dielectric strength before engergizing.

As long as Nitrogen is there no problem.Pl keep checking for the pressure drop.Once nitrogen leaks moisture will get in