Power Transformers and Shunt Reactors for Arctic Regions

Abstract

Power transformers and shunt reactors in arctic regions require special attention regarding: - Cold start - Flow of coolant - Lubrication - Embrittlement - Shrinkage - Iceload on bushings An analysis carried out reveals that a cold start - the apparatus is then at ambient temperature - represents an onerous condition, since no major cooling oil flow can take place and dangerous local hot spots may occur. While these cold starts for power transformers from extremely low temperatures (≤ -30°C) can usually be avoided, they might be necessary for the stability of the system in the case of shunt reactors. The adequacy of the design of a modern 55 MVAR 735/√3 kV shunt reactor has therefore been demonstrated in a cold start from -50°C with all essential temperatures monitored, Once certain necessary precautions have been taken, the service experience from cold regions confirms that satisfactory performance of power transformers and shunt reactors can be achieved.