— Series VMI
Construction and function
Technical changes reserved
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3 Construction and function
Components
Housing.
Electrical connection:
The electrical connection is made via 5-pin
plug M12x1.
Operation / flow indicator LED.
Process connection:
The process connections are available in
different sizes.
Type plate (sticker).
Construction
The measuring tube with its earthing sleeves and electrodes passes
through the housing and forms the external process connection of the
VMI.
A magnetic field for the measurement process is generated inside the
sensor housing, which also contains the sensor and signal condition-
ing circuitry.
The two stainless steel electrodes are located in the middle of the
measuring tube between the earthing sleeves.
The VMI does not need any moving parts to make measurements. The inside of the measur-
ing tube is completely open, allowing the fluid to flow unhindered through the measuring tube.
Function
The magnetic inductive flow sensor operates in accordance with the principle of induction, i.e.
a DC voltage is generated by the movement of a conductor in a magnetic field:
The measuring tube of the VMI is located in a magnetic
field (B).
An electrically conductive liquid (Q) flows through the
measuring tube. The positive and negative charge car-
riers are deflected in opposite directions.
A voltage perpendicular to the magnet field is gener-
ated and picked up by the two electrodes.
The resulting induced voltage is proportional to the
mean flow velocity of the liquid.
The electronics of the VMI converts the induced voltage to a flow-proportional frequency sig-
nal.
