Gassing in Furnace Transformer
Gassing in Furnace Transformer
(OP)
I have a customer with a 60 MVA National Industri unit that had circulating current problems that caused two of the top core bolts to be eroded away and break. All 8 core bolts were replaced and positively grounded. The unit was put into service in June-07 and is once again gassing at a high rate of rise (combustibles)
Hydrogen (H2):234
Methane (CH4):198
Ethane (C2H6):41
Ethylene (C2H4):334
Acetylene (C2H2):26
Carbon Monoxide (CO):33
Carbon Dioxide (CO2):332
I did an internal and have eliminated the core bolts/tap changer and secondary bus. Furans and metals are good!
Has anyone dealt with this type of problem as it relates to a furnace transformer? Any help/suggestions would be appreciated!
HoJoCo
Hydrogen (H2):234
Methane (CH4):198
Ethane (C2H6):41
Ethylene (C2H4):334
Acetylene (C2H2):26
Carbon Monoxide (CO):33
Carbon Dioxide (CO2):332
I did an internal and have eliminated the core bolts/tap changer and secondary bus. Furans and metals are good!
Has anyone dealt with this type of problem as it relates to a furnace transformer? Any help/suggestions would be appreciated!
HoJoCo






RE: Gassing in Furnace Transformer
RE: Gassing in Furnace Transformer
Samples listed left to right(9-13-07)(8-29-07)(8-25-07)
Hydrogen (H2): 234, 134, 0
Methane (CH4): 198, 110, 6
Ethane (C2H6): 41, 33, 7
Ethylene (C2H4): 334, 194, 46
Acetylene (C2H2): 26, 17, 4
Carbon Monoxide (CO):33, 17, 27
Carbon Dioxide (CO2):332, 213,163
RE: Gassing in Furnace Transformer
You really should be taking this transformer out of service before it takes itself out and you have a big problem and possibly people hurt. The transformer should be disassembled and thoroughly inspected to find the cause of this problem.
Also see http://
RE: Gassing in Furnace Transformer
Acetylene is a gas that you don't wanna have.
It can only be produced by arcing.
Does the transformer has an on-load tap-changer?
Does the on-load tap-changer has a separate oil tank?
If not, you have a problem.
I guess the other gases are produced by the heat around the arcing area.
RE: Gassing in Furnace Transformer
The unit is still gassing at a high rate!
Samples listed left to right(10-4-07)(9-13-07)(8-29-07)(8-25-07)
Hydrogen (H2): 497, 234, 134, 0
Methane (CH4): 416, 198, 110, 6
Ethane (C2H6): 82, 41, 33, 7
Ethylene (C2H4): 712, 334, 194, 46
Acetylene (C2H2): 65, 26, 17, 4
Carbon Monoxide (CO):52, 33, 17, 27
Carbon Dioxide (CO2):430, 332, 213,163
RE: Gassing in Furnace Transformer
Would that stop the circulating currents, or increase them? Were the materials correct?
The opposite direction would be, of course, to insulate them.
RE: Gassing in Furnace Transformer
I didn't understand exactly what bolts were grounded. The bolts that press the core?
Something terrible is stalking between the high voltage potentials
RE: Gassing in Furnace Transformer
Then I suggest consulting the manufacturer.
RE: Gassing in Furnace Transformer
I was away for some time! The core bolts are insulated from the core as they pass through the clamping rings. THey are then intentially grounded at one end to cause them to be at the same potentail and eliminate circulating currents. This design was from the manufacturer.
RE: Gassing in Furnace Transformer
Could it be that the OLTC tank is leaking (or communicating) its oil into the main tank.
I had one situation, where the conservator was common for main tank and OLTC tank oils, then the separation between them was having weld problems.
RE: Gassing in Furnace Transformer
Something terrible is stalking between the high voltage potentials
RE: Gassing in Furnace Transformer
Testing for this situation is sometimes nasty in that one must lift the manufacturer's core ground and megger the core against the case. There should be good insulation resistance with the core ground connection opened. If not, you have an inadvertent core grounding problem.
Occasionally the inadvertent ground can be 'burned' free by application of high current and low voltage to the core with the case as the return. If this doesn't work, though, you're looking at an untanking in most cases.
old field guy