Dissolved Gas Analysis

integratedSCADA recently completed the integration of a Kelman Multitrans online Disolved Gas Analyser (DGA) into TasNetworks SCADA network. The gas monitoring units are installed on two 110/11kV transformers located at North Hobart substation.

The SCADA integration project allows TasNetworks to monitor and historically trend the presence of fault gases present in the oil of transformer main tank.

We thank our client for trusting us with these key assets, with supply from this equipment feeding the Hobart CBD, Hospital, nearby schools, businesses and residence.

The presence of the following gases are detected and presented in SCADA as parts per million (ppm):
– Hydrogen
– Methane
– Ethylene
– Acetylene
– Carbon Monoxide
– Moisture
– Total Dissolved Combustible Gases (TDCG)

The gas quantities were collected into the Substation Gateway RTU from the Kelman Multitrans DGA using Modbus protocol over serial fibre optic communication. From the Substation Gateway RTU protocol conversion to DNP3 was implemented mapping the analog values to the Control Centre SCADA system (Master Station).

Using online DGA equipment provides an indication of developing transformer equipment faults, improving asset planning strategies and avoiding unplanned outages. Integrating DGA data into the SCADA system allows historical trending, alarming and real-time monitoring. In this case the rate of change of values over time becomes an important indicator of transformer condition. The historic SCADA trend data is made available through the SCADA system to key personnel involved in primary asset performance.

Oil temperature monitoring and fan control is supplied by a Dynamic Ratings DRMCC a PLC based transformer monitoring system.

DGA

Dissolved gas analysis (DGA) is the study of dissolved gases in insulating oil, with the concentration and rate of change used to identify developing electrical faults.