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Technical data
Measuring principle
Measuring system
34
15
Technical data
15.1
Application
The measuring device is intended only for the flow measurement of liquids with a
minimum conductivity of 20 µS/cm.
To ensure that the device remains in proper operating condition for its service life, use the
measuring device only for media against which the process-wetted materials are
sufficiently resistant.
15.2
Function and system design
Following Faraday' s law of magnetic induction, a voltage is induced in a conductor moving
through a magnetic field.
Ue
Induced voltage
B
Magnetic induction (magnetic field)
L
Electrode spacing
I
Current
v
Flow velocity
In the electromagnetic measuring principle, the flowing medium is the moving conductor.
The voltage induced (U
) is proportional to the flow velocity (v) and is supplied to the
e
amplifier by means of two measuring electrodes. The flow volume (Q) is calculated via the
pipe cross-section (A). The DC magnetic field is created through a switched direct current
of alternating polarity.
Formulae for calculation
• Induced voltage U
= B · L · v
e
• Volume flow Q = A · v
The device consists of a transmitter and a sensor.
The device is available as a compact version:
The transmitter and sensor form a mechanical unit.
U
e
I
v
B
I
L
Magphant
A0028962
Endress+Hauser
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