The partial discharge module measures electrical partial discharges (PD) in the transformer, bushing, and when applicable, the connected Iso-Phase Bus. The DTM may be ordered with up to two optional (E) modules.
Electrical PD monitoring is the perfect second level diagnostic tool to complement DGA and bushing monitoring systems. While a DGA system can indicate the type of fault, the electrical PD system can identify electrically where a fault is in the tank (identifying the phase and the winding).
Advanced Analytics
The key analytic for bushing monitoring is the magnitude and trend of the current imbalance. A DTM can provide system alarms on both of these quantities. Secondary analytics include behavior of the current imbalance with top oil temperature and the vector of the current imbalance. The magnitude of the current imbalance will provide information as to how severe the problem is. The vector will provide the indication of which bushing is failing and will identify if the power factor or capacitance of the bushing is changing.