Buchholz Relays | Protection of Oil Filled Transformers
Protection of Oil Filled Transformers | Large UK Stocks | Competitive Prices
PBwel Buchholz Relays are one of the few true cast body types in the world, developed in conjunction with the British Central Electricity Generating Board (CEGB).
PBwel offers a range of relays for small and mid-size transformers, many of which are used in substations across the world with an excellent track record of service.
Many relays remain in service after 50+ years satisfactory monitoring and PBwel have a proven track record of designing new solutions for any transformer protection required – form part of PBwel.
PBwel offer a range of single and double element type relays as part of their MV & HV Electrical Products as well as a range of relays accessories such as dry air pump, oil and gas sampling kits and diode protection units.
Most faults in an Oil Filled Transformer are accompanied by the generation of gas.
By using a suitable relay, the formation of gas can be used as a warning of a developing fault.
Once a specified volume of gas has collected within the relay, the alarm element will cause an alarm indication.
If there is a more serious fault within the Transformer, the trip element will function. The trip element will cease the functioning of the Transformer to protect it from further damage, and protect those working around it.
Possible Causes for Alarm Indication
- Broken-down core bolt insulation
- Shorted laminations
- Bad contacts
- Overheating of part of the windings
Possible Causes for Relay Trip
- Earth faults
- Winding short circuits
- Puncture of bushings
- Short circuits between phases
Buchholz Relays Product Range
- Buchholz Relays | Reed Switch Type Relays
- Buchholz Relays | Mercury Switch Type Relays
- Buchholz Relays | Single Element & Tap-Changer Type Relays
- Testing Buchholz Relays Using Dry Air Pumps
The Buchholz Relays should be mounted in the connecting pipe between the transformer and conservator tank. This pipe should be as long and as straight as possible, and must be arranged to slope upwards, towards the conservator at an angle within the limits of 3 to 7 degrees to the horizontal.
Buchholz Relays Characteristics
|Steady Oil Flow (mm/sec) to operate trip element switch||Oil level (cc) to operate Alarm Element Switch @ 500 Inclination|
|Model||Pipe angle 1º Not less than||Pipe angle 9º Not more than||Min||Max||For equipment containing|
|1DE||1000||1300||200||300||Up to 1000 litres 1000 kVA|
|2DE||1100||1400||200||300||1001/10,000 litres 1001/10,000 KVA|
|3DE||1200||1600||200||300||10,000/50,000 litres 10,001 KVA/99 MVA|
|3DE/HF2||1900||2500||250||350||50,000 litres + 100 MVA|
See images in attached pdf for further information on the below table – Click here