What is Buchholz Relay ? | working ,construction | Electronicsinfos

What is Buchholz Relay?

    Buchholz Relays is a Gas Operating Relay that is used for the Internal protection of the Transformer is called Buchholz Relay. This is mounted on the power transformer to protect it from Dielectric Failures. This is located between the conservator and the main tank of the transformer. Buchholz relay used with immersed oil transformer.

    what is buchholz relay in transformer

    Construction of Buchholz Relay

    There are two main elements of Buchholz Relay one is float and another Element is a baffle plate. There are two floats in the upper element one is connected to Trip Circuit that works when any emergency condition is occur and another float is connected to the alarm circuit that generates an alarm signal. The Float is attached with a hinge in such a way that it can move up and down easily. The movement depends on the oil level. The lower element is consist of a mercury switch and baffle plate that change their direction when oil is entering with high pressure.

    Working Principle of Buchholz Relay

    Buchholz relay is working on the principle of gas actuating relay. When any Internal fault occurs due to the Decomposition of insulating oil. The oil bubbles are produced in the oil. This bubble is moving toward the conservator and strikes the upper relay chamber. The b1 float tilt due to the movement of bubbles and external Mercury contacts C1 is close. when c1 close the alarm is operated.

    When heavy Faults occur in a transformer due to the heavy current passed in the oil the decomposition process start and the oil changes into gases. These gases strike with the lower float and c2 contact is close. after that circuit is trip and the transformer is disconnected from the main supply. This relay is only operated when the temperature reached up to 150 degrees if sometimes the transformer is overload Buchholz relay is not working.

    Advantages of Buchholz relay

    Buchholz relay is a protective device used in oil-immersed transformers to protect them from faults such as internal short circuits, insulation failure, and other related issues. Some of the advantages of the Buchholz relay are:

    1. Early Fault Detection: The Buchholz relay can detect the faults that occur within the transformer at an early stage. This helps to prevent severe damage to the transformer and avoids the need for costly repairs.

    2. Sensitivity: Buchholz relay is highly sensitive and can detect faults that are not easily detected by other protective devices. This allows for quick and accurate detection of faults and helps to prevent further damage.

    3. Protection against transformer oil degradation: Buchholz relay can also detect the presence of moisture or other contaminants in the transformer oil. This can help to prevent oil degradation, which can lead to further damage to the transformer.

    4. Maintenance: Buchholz relay is easy to maintain and can be checked periodically for faults or other issues. This helps to ensure that the protective device is functioning properly and can provide reliable protection to the transformer.

    5. Cost-effective: Buchholz relay is a cost-effective protective device that provides reliable protection to transformers. This makes it an ideal choice for small to medium-sized transformers where the cost of more complex protective devices may be prohibitive

    Disadvantages of Buchholz relay

    The Buchholz relay is a protective device used in oil-filled transformers. While it has some benefits, such as detecting and isolating faults in transformers, it also has several disadvantages. Here are some of them:

    1. Limited sensitivity: The Buchholz relay is not very sensitive to minor faults or malfunctions in the transformer. This means that it may not always detect a problem until it has already become quite serious.

    2. False alarms: The relay may sometimes give false alarms, which can lead to unnecessary shutdowns or maintenance activities. This can be particularly problematic in critical applications where uptime is essential.

    3. Maintenance requirements: The Buchholz relay requires regular maintenance and testing to ensure that it is functioning properly. This can be time-consuming and expensive, and if it is not done regularly, the relay may fail to operate when needed.

    4. Complexity: The Buchholz relay is a relatively complex device, which can make it more difficult to install, operate, and maintain compared to other types of protective devices.

    5. Compatibility: The relay is designed to work with oil-filled transformers, so it may not be compatible with other types of transformers or electrical equipment.

    6. Cost: The Buchholz relay is typically more expensive than other types of protective devices, which can be a factor in some applications.

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