portfolio single project
portfolio single project
portfolio single project
portfolio single project
portfolio single project
portfolio single project

EB series (ex BR/DR series)

The most popular Buchholz relay for oil-immersed power transformers


  • Waterproof (IP65 protection degree)
  • Large inspection window
  • Suitable for replacing similar existing and old models (of any brand)


Inlet diameter 25mm, 50mm and 80mm
Waterproof (IP65 protection degree)
Body in aluminum alloy casting
Connection executions Flanged or threaded
Window material PMMA or tempered glass
Environmental conditions from -60°C up to +70°C
Oil flow rate from 0,65m/s up to 2m/s
Wiring diagrams availability from 1 up to 4 contacts
Finishing for exreme/high corrosive environments
Gas collecting device RG3.2 available
Download PDF
Full catalogue pdf
Order form pdf



A Buchholz relay is a type of oil- and gas-actuated protection relay universally used on all oil-immersed transformers with a rating greater than 500 kVA – conservator type. Buchholz relays are used to protect transformers from faults occurring inside the transformer.
Short circuit faults such as inter-turn faults, incipient winding faults and core faults may occur due to overheating, bad connections and ageing. A Buchholz relay will sense such faults and close the alarm circuit. The Buchholz relay functions based on the fact that an electrical fault inside the transformer tank is accompanied by the generation of gas; if the fault is severe enough, it will be accompanied by an oil surge from the tank to the conservator.
The EB series Buchholz relay is waterproof and features an IP65 protection degree, enabling its usage even in very rainy and wet environments.
The EB series is even equipped with a large graduated window, allowing clear and easy inspection from the outside.
The EB series Buchholz relay has been designed in order to enable the replacement of both similar old (DIN 42566) and new models (EN50216/2).
The EB series is also suitable for use with a RG3.3 gas collecting device that allows gases to be drained from the relay accumulation chamber operating at eye level.



Relay type Inlet diameter Connection design Flange execution Bolt circle execution Standard reference Catalogue
EB024 25 mm Threaded 1 1/2" G // // EN 50216 pdf
EB 25 Flanged Round with 4 holes PN10 pdf
EB050 5 mm pdf
EB 79 80 mm
EB 80 Round with 8 holes
BQ80 Square with 4 holes pdf
Gas collecting device (suitable for EB 50 and EB 79/EB 80)
RG3.2 model pdf
Wiring diagram pdf
EB series - assembly sketch pdf
Gas analyzer for Buchholz Relay pdf

X Close