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Tree Tech Model MBR
The Membrane/Bag Break Relay (MBR) is a device capable of
detecting the rupture of the rubber membrane or bag used in oil
preservation systems on power transformers and reactors.
The MBR is comprised of an optical sensor that must be mounted on
the membrane or inside the rubber bag (on the air side), and a
control unit located in the transformer control panel. The sensor is
provided with a polysulfon capsule containing a emitting LED and a
trigger circuit. The control unit has a reversible contact and two
LED's, one to signal the membrane or bag rupture, and another to
signal the on/off status.
The MBR operation is based on the principle of light reflection.
When there is no oil present, the light produced by the emitting-LED
is completely reflected internally by the capsule dome and captured
by the optical receiver. If the oil covers the capsule, the
reflection effect on the dome limits change. The rupture causes part
of the emitted light to disperse in the oil, and the amount of light
that reaches the optical receiver is reduced. This change in light
refection causes the unbalancing of the coupling circuits and the
actuation of the signal contact.
The output contact is reversible, and its operation mode (operate or
return to rest mode in case of membrane failure) is selected by
means of an external jumper.
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