Where are Buchholz relays used?

Where are Buchholz relays used? Correct Answer Transformers

[ alt="F1 U.B D.K 18.09.2019 D 2" src="//storage.googleapis.com/tb-img/production/19/09/F1_U.B_D.K_18.09.2019_D%202.png" style="width: 489px; height: 371px;">

• Buchholz relay is a protection device which is normally used in large oil absorbed transformers; It is a kind of oil and gas activated relay
• Whenever a small fault happens within the electrical device, heat is generated by the fault currents
• The generated heat causes decomposition of electrical device oil and gas bubbles are generated
• These gas bubbles run in the upward direction and obtain collected within the Buchholz relay
• The collected gas relocates the oil in Buchholz relay and therefore the displacement is similar to the amount of gas collected
• The dislocation of oil causes the higher float to shut the higher mercury switch to connect an alarm circuit
• Hence, once a small fault happens, then the alarm will be activated; The collected quantity of gas specifies the level of fault occurred
• Different types of faults have different types of oil flow and thus a fault can be recognized easily, and proper action can be taken
• It is used for the transformers of rating greater than 500 KVA.