During a recent OLTC service, the customer stated that they had ongoing issues with poor oil quality. After testing, we found BDV: 28.5 kV (IEC 60156 Gap 2.5 mm), which is below the allowable level for a delta-connected OLTC. Reinhausen (Thailand) Ltd. upgraded the breather to a maintenance-free MTRAB® 2.5.
In contrast to conventional dehydrating breathers, the MTRAB® 2.5 regenerates the silica gel desiccant via sensor control, and at the ideal time – based on the breathing cycle of the OLTC/transformer. This eliminates the need for costly replacement of the desiccant. Visual inspections are no longer necessary thanks to integration into the control and SCADA systems.
The oil has been replaced and tested to above 60kV (IEC 60156 Gap 2.5 mm), back into the safe operating range.