High Voltage Testing in Electrical Substations

The use of UV cameras is becoming widely recognised as a safe, non contact method of checking electrical installations in substations.  the following are typical examples of the inspections that can be carried out using the DayCorII camera:

• Polymer insulators in particular are sensitive to corona. Of special concern is corona on the end fitting and cases when it is in contact with the fibreglass core of the insulator. Carbonised and exposed rod, split insulator sheath, holes in the sheds and damaged corona rings are conditions that may cause electrical and mechanical failures.

• Porcelain insulators - Corona is pitting into the cement and corrodes the pin of the insulator and may cause mechanical and electrical failure of the insulator. Shorted bells in a string of porcelain insulators will usually show corona on the first healthy bell in the string. Cracks in the cement or porcelain will show corona. Chipped or missing bells will not make corona.

• Broken conductor strands will usually create corona and may cause severe radio interference.

• Loose spacers in a conductor bundle may damage the conductors and cause corona.

• Contaminated insulators often show corona, which will persist if the insulator was not adequately cleaned.