ET series (italian standard)

ET SERIES
An Italian designed Buchholz relay for oil-immersed power transformers

KEY FEATURES

• Inlet diameter up to 100 mm
• Waterproof (IP65 protection degree)
• Large inspection window
• Suitable for replacing similar existing and old Italian models

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 PRODUCT DESCRIPTION

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 ET series Buchholz relay is waterproof and features an IP65 protection degree, enabling its usage even in very rainy and wet environments.
The ET series is even equipped with a large graduated window, allowing clear and easy inspection from the outside.
The ET series Buchholz relay has been designed in order to enable the replacement of both similar old (DIN 42566) and new models (EN50216/2).
The ET 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 type	Flange design	Bolt circle execution	Standard reference	Catalogue
ET025 (old T1)	25 mm	Flanged	Round with 4 holes	PN6
EU26 (old T0/DN25)				PN6 + PN10 (special drilling)
ET 50	50 mm			PN6
T3	75 mm
DN100	100 mm		Round with 8 holes	PN10
Others
Wiring diagram