Fill Up or Top-up 132kV With SF6 Gas

NOT!!

Compared to how safe in not topping it up?

What is the method of adding gas?

When working with 132 KV equipment- if you have to ask a question like this you aren't qualified to do it.

I know that. But if you can't answer the question, then neither are you. After all, the question is perfectly sensible.

I think JNB's response was direct at the OP.

JNB is quite right, if the OP's asking this question, the no I don't think it is a perfectly sensible question. Unless somebody has experience of the OP's siite in question and, can supply a safe working/maintenance procedure for the TX in question. Then a very dangerous situation could arise. Would you like that on your conscience?

A formal Risk Assessment would be the correct indicator to use. Get it on file, so that when someone gets hurt/killed it can be used as a backside-covering device.

Here: http://en.wikipedia.org/wiki/Risk_assessment

On one job that I on, after putting the 238 KV sf6 bus system into service,it was discovered that the gas in one phase was a little damp. While the phase was in service, I added dry gas, which raised the pressure. After a few hours I then would suck the gas out till just above trip pressure and the refill with dry gas till the buss was over pressured again. I would do this two or three times a shift. I did this for several days till the moisture content of the gas would meet specs. I had to do this several times as for some strange reason the moisture content of the gas would rise. I wanted to inject gas in one end of the bus and suck from the other, but the contractor I worked for didn't want to pay for the extra fittings. The moisture problem was finally traced to the porcelain bushing on the SF6 circuit breaker being machined during manufacturing. When it was shipped rain got into the open porcelain face. Not sure if this was proper but it worked with no lasting effects.

A side bar to this:

Want a really deep voice , breath SF6 gas. A word of caution, don't do this at home.

I don't know much about high voltage breakers, but can tell you that if your breaker is low on SF6, it probably has a leak. Most leaks allow atmospheric gas to enter while the contained gas leaks out. This means that if you refill the breaker with SF6, the contaminating gasses will still be present in substantial quantities. It may pay to start from the beginning and do the job correctly.

Two question that need answering:

1. Is it safe to top of when the transformer is energized - NO it is not

2. Is it safe to top of the transformer - Yes stop it before you damage it and then have bigger problems.

It depends on what the equipment manufacture states and what policies are in place at the switchyard/substation, etc.

Generally it is not allowed due to safety reasons, but generally this is not a big problem as the gas should not leak out unless there is a serious problem with the switchgear (in which case it needs to de de-energised anyway).