Current Transformer type SBD 88

[kunkuta]

We are installing curent transnformers type SBD 88 manufactured by Balteau in 1983 (S/No. 4616/1/1 for one of them). These units were procured from Lesotho Electricity board. This design compared to the SBD 82/2 has a pressure gauge at the bottom. Now, on two units these gauges are reading Zero. We do not have a service manual for this equipment and we want to establish what pressure these gauges are monitoring. We need this information urgently. Kindly advise us on what to do.

 

[peterb]

A little web surfing revealed that Balteau was purchased by Alstom in 1987. You could try contacting them via their website at

http://www.alstomtransformers.com/.

 

[ongchazira]

Is the transformer is oil filled type. Normally the oil filled CTs has nitrogen blanketing on the top which is filled with and maintained at a slightly higher pressure than atmosphere. This is for preventing the oil-air contact. If there is loss of this nitrogen, then it will lead to deterioation of the oil. If the pressure reads zero, then you have to replace the oil, dryout the CT winding and fill with fresh nitrogen.

 

[electricpete]

My thought was also that the pressure would indicate either nitrogen pressure above oil, or else SF6 pressure. Either way zero doesn't sound too promising....so you are doing the right thing to investigate further.

 

[kunkuta]

Well, both the SBD 82/2 and SBD 88 uses the inverted design with the active parts located in the top of the transformer. Information from Alstm T & D site, the SBD 82/2 uses an epoxy resin insulation which is cast under vacuum plus the pocerlain insulator. They further say no specific maintenance is necessary as there is no liquid or gaseous material to be checked periodly. Now, this design does not look any different from the SBD 88 and I find it rather unsual that we have a gauge when we are not monitoring anything. I sent a mail to Alstom T & D but I haven't received any feedback yet.