PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
(OP)
Dear Respected engineers,
Referring to the attached photographs, we have a mobile GIS (Gas Insulated Substation), made in 1992 by ABB Lodi, Italy. The mobile GIS primary voltages if 132kV at 50Hz.
The problem we are facing is that past few months, is that PT drops its pressure of SF6 gas, since the pressure drops in only PT/VT and does not drops in other compartments (like isolator and breaker), so we suspect we have a leakage at PT/VT Chamber. Now, we think in order to attend the leakage of SF6 from PT, we have two options.
1. Either we shall remove the PT from GIS (as we are using it only for monitoring voltages and not using in protection circuit) and place the end plate at the bottom and close the GIS. Problems in this option: There is very little space between bottom of PT and we don't know how to remove PT by using this little space,
2. Or we shall dismantle the PT from GIS and replace the O rings or attend any more leakage, but for replacing internal O ring (Most probable leakage from there) will require PT to be open to atmosphere. But, as far as I know, PT of GIS should never be allowed to open atmosphere as moisture penetrates into insulation, ultimately leading to failure of PT/VT. Again, little space between PT bottom and floor.
Any one, done this before, please suggest, which option is better and how to do it? Also, if you have any better option, please suggest that also.
Referring to the attached photographs, we have a mobile GIS (Gas Insulated Substation), made in 1992 by ABB Lodi, Italy. The mobile GIS primary voltages if 132kV at 50Hz.
The problem we are facing is that past few months, is that PT drops its pressure of SF6 gas, since the pressure drops in only PT/VT and does not drops in other compartments (like isolator and breaker), so we suspect we have a leakage at PT/VT Chamber. Now, we think in order to attend the leakage of SF6 from PT, we have two options.
1. Either we shall remove the PT from GIS (as we are using it only for monitoring voltages and not using in protection circuit) and place the end plate at the bottom and close the GIS. Problems in this option: There is very little space between bottom of PT and we don't know how to remove PT by using this little space,
2. Or we shall dismantle the PT from GIS and replace the O rings or attend any more leakage, but for replacing internal O ring (Most probable leakage from there) will require PT to be open to atmosphere. But, as far as I know, PT of GIS should never be allowed to open atmosphere as moisture penetrates into insulation, ultimately leading to failure of PT/VT. Again, little space between PT bottom and floor.
Any one, done this before, please suggest, which option is better and how to do it? Also, if you have any better option, please suggest that also.






RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
Given that the sub is a mobile unit, have you considered taking
it back to ABB for repair?
Thanks,
Alan
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
I do not know where the substation is located; if the cost of bringing the mobile substation to Lodi is too high, probably it could also be possible to repair the VT by changing the o-ring on site, but being it quite a critical task, it should be performed by the manufacturer.
Si duri puer ingeni videtur,
preconem facias vel architectum.
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
England's National Grid Company injected wax into the inter-seal space between the inner and outer O-rings in an attempt to avoid dismantling large runs of SF6 IPB after the inner ring failed. I'm not sure if that was their own undertaking or whether it was supported by either ABB Hosag at Baden or ABB Westboro in the US. Baden is still ABB, Westboro is now AZZ CGIT Westboro. Maybe worth considering.
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
Thanks for advice, for the first time we also thought same, but due to some economical reasons and other management problems, we are provided the task to attempt it in house. So, kindly guide how to do it.
Dear Scotty UK,
Thanks for comments. Yes, we shall create a tent around the mobile GIS and then do the work. But please guide how to do it??
Don't have any drawings or manuals. got it from some other department. so, nothing came except its control wiring drawing.
Kindly help and guide how to attempt it. Its ELK 04 model.
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
Get factory help, it's going to be a lot cheaper than trying to put it right after you make a mistake.
And 'tent' is almost certainly the wrong idea. Get it indoors into a clean workshop, and seal the building up as much as you can before you crack the seals.
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
RE: PT/VT Repair/Removal in Mobile GIS (Gas Insulated Substation) of ABB
Hire a certified expert and have your crew support him. The GIS expert will have all of the necessary tools and gas handling equipment. It's more than you think.