Omega FMG90B Series, User Manual, Page: 8 / 24

Construction and function FMG90B Series
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3 Construction and function
Components:
 Housing:
The Housing consists of plastic and has the
IP65 degree of protection.
 Electrical connection:
The electrical connection is made via 4-pin
plug M12x1.
 Operation / flow indicator LED.

Process connection:
The process connections are available in
different sizes.
Construction:
The measuring tube with its grounding sleeves and electrodes passes
through the housing and forms the external process connection of the
FMG90B.
A magnetic field for the measurement process is generated inside the
housing, which also contains the sensor and signal conditioning
circuitry.
The two stainless steel electrodes are located in the middle of the
measuring tube between the grounding sleeves.
The FMG90B does not need any moving parts to make measurements. The inside of the
measuring tube is completely open, allowing the fluid to flow unhindered through the
measuring tube.
Function:
The magnetic inductive flow sensor functions according to the induction principle. A DC
voltage is generated by the movement of a conductor in a magnetic field:
The measuring tube of the FMG90B is located in a
magnetic field (B).
An electrically conductive medium (V) flows through
the measuring tube. The positive and negative charge
carriers are oppositely deflected.
A voltage (U) is generated at right angles to the
magnetic field, which is picked up by the two
electrodes.
Thereby, the induced voltage is proportional to the
average flow velocity of the liquid.
The electronics of the FMG90B converts the induced voltage into a flow-proportional
frequency signal.