What is Buchholz relay and where it is used?

protection of transformer against all internal faults. protection of transformer against all external faults. protection of transformer against both internal and external faults.

What is Buchholz protection?

The Buchholz protection is a mechanical fault detector for electrical faults in oil-immersed transformers. The Buchholz (gas) relay is placed in the piping between the transformer main tank and the oil conservator. The conservator pipe must be inclined slightly for reliable operation.

What is advantage of Buchholz relay?

Advantages of Buchholz Relay It is the simplest form of transformer protection. A Buchholz relay is a fundamental device for transformers, it keeps internal gas accumulation and oil flow monitored and under control. It detects incipient faults much earlier than the other forms of protection.

Which gas is used in transformer?

Typical gases that appear in transformers are hydrogen (H2), methane (CH4), ethane (C2H6), ethylene (C2H4), and acetylene (C2H2). These gases begin to form at specific temperatures and dissolve within the insulation oil of a power transformer, as shown in Figure 1.

How do we test Buchholz relay during maintenance?

Just open the drain plug at the bottom of the relay,for oil draining ,same time one have to open the airplug given at the top of the relay. oil level inside the relay decreases which was full before. Alarm appears at one point n then trip command occurs……

What is Buchholz relay which equipment is protected by it?

Answer: Buchhols relay is one of the most important equipment used in power system. It is simply a gas actuated relay. Generally, Buchholz relay is used for the protection of power transformer of reading exceeding 500 KVA. It provide protection against internal faults of transformer.

What are limitations of Buchholz relay?

The various limitation of the Buchholz relay are,

• Can be used only for oil immersed transformers having conservator tanks.
• Only faults below oil level are detected.
• Setting of the mercury switches cannot be kept too sensitive otherwise the relay can operate due to bubbles, vibration, earthquakes mechanical shocks etc.

What is the rating of oil immersed transformers where Buchholz relays are used in universal practice?

750 kVA
It is a universal practice to use Buchholz relays on all such oil immersed transformers having ratings in excess of 750 kVA. The Buchholz relay is a protective rely for equipment immersed in oil for insulating and cooling purpose.