JUMO flowTRANS MAG H01, Operating Manual

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2 Design and function
2 Design and function
2.1 Measuring principle
The Faraday Laws of Induction provide the basis for the electromagnetic flowmeter measurement. A
voltage is generated in a conductor as it moves through a magnetic field.
When this measuring principle is applied through a device, the conductive measurement medium flows
through a pipe in which a magnetic field is generated perpendicular to the flow direction (see figure).
The voltage induced in the measurement medium is tapped by two diametrically arranged electrodes.
This measuring voltage V
E
is proportional to the magnetic induction B, the electrode gap D as well as
the average flow velocity v.
Given the magnetic induction B and the electrode gap D are constant values, it follows that there is a
proportionality between the measuring voltage V
E
and the average flow velocity v. The calculation of the
volumetric flow rate demonstrates that the measuring voltage V
E
is linearly proportional to the volumetric
flow.
The induced measuring voltage is converted into standardized, analog and digital signals in the trans-
mitter.
(1) Magnet coil
(2) Measuring pipe in the electrode plane
(3) Measuring electrode
V
E
Measuring voltage
B Magnetic induction
D Electrode gap
v Mean flow velocity
qv Volume flow rate
G00005
(1)
(2)
(3)
U
E
~
v D B ⋅ ⋅
qv =
v
D
⋅
4
2
π
U
E
~ qv