The Buchholz relay MBP according to EN 50216-2 acts as a protector of transformers and regulators with expansion tanks. It is connected to the pipeline between the boiler and the expansion tank. The Buchholz relay MBP acts as a protective device equipped with one alarm or two switching contacts (alarm / transformer shutdown) per float.
Each Buchholz relay is individually tested for tightness and proper operation in a test facility.

We offer the Buchholz relay MBP according to the specifications of the European standard EN 50216-2 and special design. For simplified gas or oil sampling from the ground you will find our MGSD gas sampling device, which is connected via copper pipe directly to the Buchholz relay.

Overview

Details of functions
Your advantages at a glance
Buchholz relay MBP according to EN 50216-2
Buchholz relay MBP special design
Gas sampling device MGSD
Assembly
Order options
Function video

Functions of the Buchholz relay MBP

Gas formation: The formed gas rises in the insulating fluid, collects in the Buchholz relay and suppresses the fluid. The upper float drops with the falling oil level and opens the upper Reed switch.

Loss of oil due to leakage: When the oil level drops, the upper float drops first and the upper Reed switch opens. As the oil level drops, the pipeline and the expansion tank empty and the lower contact closes.

Sudden pressure wave: The pressure wave hits the valve arranged in the isolation fluid flow. The valve moves in the flow direction and pushes the lower float downwards. The lower switch is activated and can immediately switch off the transformer. When the pressure wave subsides, the valve returns to its original position.

Your advantages at a glance

-Reed switch for detection of gassing and falling oil level
-Protection valve against excessive oil flow rate
-Float chamber separated from the switching mechanism
-Changing Reed switches without interfering with the oil circuit
UV-resistant C5-M coating (SOLIDLINE)
-1/8 ball valve for sampling
-Contact switch mechanical function test (test button)
-Pneumatic function simulation (optional)
Buchholz relay MBP according to EN 50216-2
According to EN 50216-2 our Buchholz relay MBP complies with the requirements of the European standard EN 50216-2. The standard specifies operating limits, dimensions, performance and electrical characteristics. The housing is manufactured using the die-cast aluminum process and, in combination with C5-M powder coating, offers the highest level of UV and corrosion resistance.

Features of our Buchholz relay:

-Nominal pipe sizes: DN 25 (1); DN 50 (2); DN 80 (3)
-Connection: Flange connection, (DN 25 also with threaded connection G 1 1/2)
-Switch element Reed switch
-Number of switching contacts: Up to 2 NO or 2 CO (SPDT) switches per function
-Ambient temperature: -30°C to 55°C
-Protection class: IP65 (optional IP68)
-Flow rate: 0.65 m/s; 1.00 m/s; 1.50 m/s; 2.00 m/s
-Pinch cover Magnetic retention
-Response of the gas accumulating switching system: 200 cm³ – 300 cm³
-RAL colors commonly used in tiles

Buchholz relay MBP special design

Special design developed according to customer requirements. While the functions are the same, the main differences are in flange dimensions, bolt circle, nominal diameter DN76 and body width.

Gas sampling device MGSD

In large power transformers the Buchholz relay is located at a height that is difficult to access (between the boiler and the expansion tank). The MGSD gas sampling unit is connected to the Buchholz relay via a copper tube and can be installed anywhere in the transformer. It is used for simplified gas or oil sampling from the ground. Optionally, an additional oil sampling valve and a valve for pneumatic functional testing of the switches can be added.

Installation of the Buchholz relay MBP

The Buchholz relay is mounted between the transformer vessel and the expansion tank. For the correct installation of the Buchholz relay, the following must be observed:

The red arrow points to the expansion tank (arrow points in the direction of flow).

The inclination angle of the pipeline to the expander must not exceed 0° and max. 5 ° must not exceed.
Gases must have unobstructed access to the Buchholz relay.
For more detailed information about the various Buchholz relays and possible ordering options, please contact us.