Oil Transformer top up
Oil Transformer top up
(OP)
Hi
Due to plant condition we are attempting for oil top up of ABB power transformer 35MVA in energizing state .
the planned procedure is remove the breather pipe in top of the conservator and force the oil to flow unit reaching the predetermined level.
The questions are;
Is there any risk of triggering the buchholz relay ?
Are there any safety risks ?
Due to plant condition we are attempting for oil top up of ABB power transformer 35MVA in energizing state .
the planned procedure is remove the breather pipe in top of the conservator and force the oil to flow unit reaching the predetermined level.
The questions are;
Is there any risk of triggering the buchholz relay ?
Are there any safety risks ?
RE: Oil Transformer top up
Deenergize and do it right.
I’ll see your silver lining and raise you two black clouds. - Protection Operations
RE: Oil Transformer top up
I'll just talk through what I see are some of the concerns. I'm not intending to tell you how to do anything, just food for your own thought in thinking about why we might do things certain ways. You're on your own to make responsible decisions.
I worked on transformers for awhile during the 90's. Some of that is a little fuzzy, but I don't ever remember adding oil to any transformer without (deenergizing and) draining then refilling under vacuum. As I recall for conservator transformers, we isolated the conservator before draining the main tank and if conservator level was low we added oil to the conservator while it was isolated.
There are a few different types of conservators. Obviously if there's a bladder in there, you probably don't want to add oil into a breather space above the bladder. It's not designed to work that way... among other things your bladder could sink and block the port to the transformer tank.
I would be worried about the risk of air bubbles trapped in the oil that cause a problem when you energize the thing. It may seem unlikely bubbles could make their way from conservator to tank but you never know. If you following normal procedures of deenergizing the transformer then there would be a wait period before you energize (maybe with pumps running) to help make sure there were no bubbles in the tank.
Also obviously if the transformer has exposed bushings you have to keep your people and equipment far enough away from those.
The transformer OEM may have some recommended procedures to consult. Your organization may have some procedures. If you are not following a well thought out procedure from someone that knows what they're doing that's sometimes a cue that you're out on a limb and you need to be extra careful.
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(2B)+(2B)' ?
RE: Oil Transformer top up
I agree it has risks otherwise and to to my knowledge no transformer manufacturer recommends it.
RE: Oil Transformer top up
RE: Oil Transformer top up
Why is it low? Is it leaking or just low from drawing off oil for testing? If it’s the latter I would say it’s time for a transformer test anyway if you’ve drawn that much oil.
Deenergize, test, and fill it up correctly.
RE: Oil Transformer top up
low1 (Electrical) ...... Can you please send me your standard procedure plan and does it approved by the manufacture .
Palletjack (Electrical)........ the oil level has reduced because of the oil remains in side Oil treatment machine during recycling ,then this issue has finger out recently .
RE: Oil Transformer top up
Bill
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"Why not the best?"
Jimmy Carter
RE: Oil Transformer top up
RE: Oil Transformer top up
RE: Oil Transformer top up
Also consider the pressure relief device (PRD). A substation crew told me about the PRD activating and spraying oil everywhere when they were adding oil to a transformer LTC compartment. It turned out the air breather was designed for small rates of airflow, and could not handle the airflow caused by filling at normal oil flow rates.
When specifying transformers, it can be useful to include a requirement that the conservator and LTC conservator are large enough to allow routine oil sampling for at least 20 years. In addition to the actual oil sample, the extra volume in the conservators should account for flushing the piping to obtain a representative sample. On a 230 kV transformer, the oil piping volume that needs flushing before sampling can exceed 10 liters.
Online filtration could certainly be considered a kind of recycling. I could see loosing a small amount of oil each time the filter is changed out. It can take dozens of hydrophilic filter changeouts to appreciable lower the water content of the transformer.
RE: Oil Transformer top up
On our transformers (newer Hyundai units), there is piping at ground level, clearly labelled "Fill", "Drain" and "Vent". These transformers are also equipped with Messko breathers. To fill (top up), we ensure the bung/plug is removed from the vent line and valving is open, connect oil pump to "fill" line and throttle valving to fill at an appropriate rate. Qualitrol pressure devices are set to operate protection at 7.5psi, I believe. Transformers also have PRD, although discharge piping is directed down into the containment in the event of a "mishap". I've topped up dozens of transformers online without any issues. We had to top up our spare transformer this fall, and as it was a slightly different design with unclear labelling, we separated the piping to the Messko breather as well to avoid issues with oil contamination in the event we were wrong in our assumptions of the proper vent piping. This transformer is not in service, so it was of little consequence anyway.
RE: Oil Transformer top up
Improper filling may lead to Buchholz trip.
Contamination may lead to a damaged transformer.
It doesn't take much conductive contamination to initiate an internal flashover.
Bill
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"Why not the best?"
Jimmy Carter