Buchholz and Gas Analysis

ETI GQ Series Buchholz relay

Australian Standard Buchholz relay for oil-immersed power transformers

ETI GQ Series Buchholz relay detects faults and minimize the propagation of any damage which might occur within oil-filled transformers. Its function is based on the fact that an electrical fault inside the transformer tank is accompanied by the generation of gas; if the fault is severe enough, it will be accompanied by an oil surge from the tank to the conservator.

• Independent switches for the upper and lower float and flow vane (GQ switch)
• Mechanical test button to test independently the three sets of switches, also remoted to man level
• Pneumatic plug to directly test the flow vane
• Inlet diameter: 25 mm/50 mm/80 mm
• Oil flow rate: from 1 m/s up to 2 m/s (other rates upon request)
• Connection executions: flanged or threaded
• Waterproof – IP 65 protection degree

Technical Data

Relay GQ25

All casting flanges are drilled to Australian Table D or 6 hole metric thread, see GQ casting


Buchholz Gas

Evolved gas in the upper chamber can be collected at ground level see drawing, known as the RAGA 2. See the technical data sheet linked below.
A variant design allows for the positioning of a valve connected to the underside of the casting for air injection onto the face of the oil flow vane, known as the RAGA 2 SC.

Technical Data

View/download the Messko Gas Quick Test product data: Messko Gas Quick Test