New devices for a dry type transformer protection and monitoring system

In this contribution new devices for protecting and monitoring dry type transformers are introduced. An online overheating protection is performed by using an optical fibre sensor, which signals an alarm if a local overheating appears. In this case an offline analysis of the transfer functions of the transformer coils can be usefully applied for the identification of interturn short circuits or similar destructions, that might have caused the local overheating. The developed monitoring system is efficient and cost-effective and can be easily installed on almost all categories of dry type transformers.