Monitoring system for transformer catch basins

When using transformers, electrical coils, and other devices operated with oil (e.g. for insulation), the energy supplier must comply with special requirements on operating such systems if a volume of more than 1 m³ or more of water-polluting liquids is used.

To prevent any malfunctions causing water-polluting liquids to escape from the overall system, all oil-filled devices have to be set up on watertight surfaces. These surfaces must be designed as a drainage surface into an external collecting chamber or as a large-scale separator. The Arbeitsgemeinschaft Industriebau (AGI), a German trade organization of industrial construction companies, has authored a technical standard that describes various structural options for designing transformer catch basins so as to comply with the German Ordinance on Installations for Handling Substances Hazardous to Water (VAwS).

The technical standard also notes that the precipitation water can be pumped out of the basin or the collection chamber after a visual inspection. This is important so that all of the oil of the transformer can be collected in case of a breakdown and not enter the environment.

Phoenix Contact offers a new system for continuous level monitoring, alarm generation, and pumping precipitation water for transformer catch basins. The water level measured by an ultrasonic sensor is continuously compared to two different limit values. If the first limit value is reached, the system generates an e-mail so that maintenance work can be planned at an early stage. If the second, critical limit value is reached, a text message is sent to on-call personnel so that action can be taken immediately. 

During the resulting station visit, the maintenance personnel performs a visual inspection of the precipitation water for oil contamination and starts the pumping process, which runs automatically. During this process, the water level is still continuously measured and lowered to an adjustable minimum volume. An additional rod probe ensures that the pumping process is stopped immediately if any oil contamination is detected. The key components of the system are certified and have received official technical approval.