Buchholz relay is a gas actuated relay. It is generally used on all oil immersed transformers having a rating more than 500 KVA. It is installed between the conservator and main tank. Therefore, such relay can only be installed in the transformers equipped with conservator tanks.
Buchholz Relay Working Principle and Construction
The Buchholz relay construction is shown in Figure. It consists of two hinged floats in a metallic chamber. One of the floats actuates the mercury switch connected to the external alarm circuit and the other float actuates the mercury switch connected to the tripping circuit.
Whenever a fault occurs inside the transformer, the oil of the tank gets overheated and gases are generated. The generation of gases may be slow or violent according to nature of the fault.
When a predetermined amount of gases accumulate in the top of the chamber of the relay, the mercury type switch attached to the float is tilted, closes the alarm circuit and rings the bell.
When a severe fault occurs, a large volume of gas is generated, the lower float is tilted and the trip coil is energized. This opens the circuit breaker and supply to the transformer is switched off.
Buchholz relay is a very simple device used for transformer protection. Moreover, it detects the developing faults at a much earlier stage and enables us to protect transformer before serious damage occurs.
Thanks for reading about buchholz relay working principle.
Transformer | All Posts
- Single Phase Transformer Working Principle
- Ideal Transformer
- Construction of Three Phase Transformer
- Types of Transformers
- Equivalent Resistance and Reactance of Transformer
- Equivalent Circuit of Single Phase Transformer
- Power Loss in a Transformer
- Open Circuit Test of Single Phase Transformer
- Short Circuit Test on Single Phase Transformer
- Transformer Efficiency
- Regulation of Transformer
- Instrument Transformers
- Polarity of Transformer Windings
- Significance of Vector Group of Transformer
- Buchholz Relay Construction | Working
- Why current transformer secondary should not be opened
- Dielectric Strength Test of Transformer Oil
- Transformer Moisture Removal Process