Buchholz Gas Relay for Transformers – Reliable Protection Device

The gas relay is a protective device used in oil-immersed transformers equipped with conservator tanks and on-load tap changers. It is installed in the piping between the transformer and the conservator and employs a baffle-type magnetic contact mechanism.

Traditional component products Buchholz Gas Relay
Digital component products Transformer Remote Contact Buchholz Gas Relay

Product Details

Buchholz Gas Relay

During transformer operation (or operation of the on-load tap changer), if a fault occurs that causes the insulation oil to
decompose, gas is generated. Once the accumulated gas reaches a certain volume, the upper float descends, closing the reed contact and activating an alarm signal.

In the event of a severe fault, an oil surge occurs inside the transformer. The resulting oil flow impacts the relay’s baffle,
moving it and causing the reed contact to close, which sends a trip signal. Additionally, if the transformer oil level drops due to leakage, the relay will also issue a trip signal.

Buchholz Gas Relay Features

The gas relay is equipped with a range of auxiliary functions, including exhaust, gas intake, manual testing, action lock, manual lock reset, manual memory reset, oil flow rate indication, gas volume indication, gas volume memory, oil flow rate memory, secondary cable waterproofing, and easy replacement of the gas intake box.

Designed for use in oil-immersed transformers (or on-load tap changers) with a capacity of 800 KVA and above, the relay features an on-site display that provides auxiliary functions such as status locking, indication, and memory. When the relay’s baffle is activated, the display unit accurately identifies this specific action signal, distinguishing it from other trip signals generated by the relay. A dedicated reset mechanism has also been incorporated to restore the signal to its original state once the fault has been cleared, significantly reducing maintenance and troubleshooting time.

Mounting size of buchholz gas relay

QJ-25 Buchholz Gas Relay

Model	H	L1	L2	d	R1
QJ1-25	214	185	170	172	95
QJ4-25	210	200	140	144	130
QJ6-25	210	200	140	144	130
QJ8-25	210	200	140	144	130
QJ7-25	210	200	140	144	130
QJ9-25	210	200	140	144	130

QJ-50 Buchholz Gas Relay

Model	H1	H2	L	L3	D	D1	D2	d	A
QJ1-50	215	60	160	12	130	100	60	M12	120
QJ4-50	220	63	185	15	125	-	-	Φ14	125
QJ19-50	220	63	185	15	125	-	-	Φ14	125
QJ10-50	220	63	185	15	125	-	-	Φ14	125
QJ11-50	220	63	185	15	125	-	-	Φ14	125
QJ12-50	220	63	185	15	125	-	-	Φ14	125
QJ13-50	220	63	185	15	125	-	-	Φ14	125

QJ-80 Buchholz Gas Relay

Model	H1	H2	L	L3	D	D1	D2	d	A
QJ1-80	230	60	160	12	130	110	85	M12	120
QJ4-80	235	80	185	15	160	-	-	Φ18	160
QJ9-80	235	80	185	15	160	-	-	Φ18	160
QJ10-80	235	80	185	15	160	-	-	Φ18	160
QJ11-80	235	80	185	15	160	-	-	Φ18	160
QJ19-80	235	80	185	15	160	-	-	Φ18	160
QJ13-80	235	80	185	15	160	-	-	Φ18	160
QJ14-80	235	80	185	15	160	-	-	Φ18	160
QJ20-80	235	80	185	15	160	-	-	Φ18	160
QJ21-80	235	80	185	15	160	-	-	Φ18	160
QJ22-80	235	80	185	15	160	-	-	Φ18	160
QJ23-80	235	80	185	15	160	-	-	Φ18	160
QJ24Z-80	235	80	185	15	160	-	-	Φ18	160
QJ31-80	235	80	185	15	160	-	-	Φ18	160
QJ33-80	235	80	185	15	160	-	-	Φ18	160
QJ41-80	235	80	185	15	160	-	-	Φ18	160

Stainless steel rain Cover (Option)

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Contact us

Shenyang Mingyuan Electric Technology Co., Ltd. is a professional manufacturer of transformer accessories with over 30 years of experience. We provide comprehensive supporting services for major transformer manufacturers, power grid systems, railway locomotives, and nuclear power facilities. Equipped with self-developed testing systems and involved in drafting national industry standards, we are committed to advancing the digitalization and localization of critical power equipment. For inquiries or cooperation, please feel free to contact us.