Table of Contents
How do you test a Buchholz relay?
On-site testing of Buchholz Relays
- Place pump on stable area of ground.
- Open unit and attach flexible pipe to non-return valve outlet using suitable spanner.
- Ensure that outlet valve is closed at right angle to ballvalve body.
- When access clear, connect flexible hose to TEST ballvalve upon Buchholz.
For what type of fault Buchholz relay is used?
Buchholz relay is used for the protection of transformers from the faults occurring inside the transformer. Short circuit faults such as inter-turn faults, incipient winding faults and core faults may occur due to the impulse breakdown of the insulating oil or simply the transformer oil.
What is the operating time of Buchholz relay?
The minimum operating time of the relay is 0.1 seconds.
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.
What is the BDV value of transformer?
A typical value of BDV Test result for 220 / 6.6 kV Transformer oil is 65 kV and moisture content should be less than 10 ppm. BDV is an important and popular test of transformer oil, as it is the primary indicator of the health of oil and it can be easily carried out at the site.
What is transformer oil name?
Mineral oil and Synthetic oil are the majorly used transformer oil. These are the petroleum products, like Naphthenic based transformer oil and Paraffinic based transformer oil. Naphthenic based transformer oils are known for their heat distribution, which is one of the main problems with transformer.
What is the unit of BDV value?
As per IEC, the minimum breakdown voltage of transformer oil should be not less than 30 KV. The BDV of transformer oil does not depend on the voltage rating of the transformer. Minimum transformer BDV value for either 11 KV, 22 KV, 132 KV is the same. The minimum transformer oil BDV is 30 KV.
What is a Buchholz relay on a transformer?
Buchholz relays have been applied on oil-filled power and distribution transformers at least since the 1940s. The relay is connected to the oil piping between the overhead conservator tank and the main oil tank of a transformer.
What are the limitations of Buchholz relay?
Limitations of Buchholz Relay 1 The relay is used only in oil immersed transformer. 2 It can only detect the fault below oil level. 3 This relay does not protect the connecting cables. Hence separate protection is used for the cables. 4 The response time of the relay is high.
What is a test port on a Buchholz relay?
Buchholz relays have a test port to allow the accumulated gas to be withdrawn for testing. Flammable gas found in the relay indicates some internal fault such as overheating or arcing, whereas air found in the relay may only indicate low oil level or a leak.
How are gases collected in the Buchholz relay?
In this way gases are collected in the Buchholz relay. When a certain volume is reached, the gases generate an alarm signal. With the two-level alarm system the initial alarm signal is generated at a gas volume of 100-200 cm³, and the second alarm signal at a gas volume of 250-300 cm³.