Air Insulated Switchgear (AIS)

Online Partial Discharge Monitoring of Dry-type Transformers
Dry type transformers are an important part of the electrical power supply and distribution system. Due to safety and environmental friendly constraints dry type construction is preferred to be used in industrial and residential structures. Main advantages of this construction are reduced fire hazard, less installation space requirement, and zero leakage risk of flammable or contaminating substances.
Similar to the oil filed transformers the dry type transformers insulation system is exposed to the most dangerous physical phenomena which are partial discharges (PD). Comparing to the oil-paper system, dry type have no so called self-healing characteristic. For example air void cannot be filled again with oil. Fast propagation and development process of PD in solid insulation leads in all cases to electrical breakdown and failure of the affected transformer. PD can be prevented through the careful material selection and design.
Exact localization of the PD signals in dry type transformer windings is one of important tasks during production or in operation.