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Mecon 02/2010
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Transmitter mag-flux M1
Caution
According to EN 50178:1997 all electrical
circuits with „protectiv safety isolation with-
out any protection against contacts” must
observe the following maximum voltages:
•
Maximum AC voltage (V
eff
) 25 V
•
Maximum DC voltage 60 V
It is strictly forbidden to connect FE to
any higher voltage!
Zero point calibration
In order to ensure that precise measurements are obtained, zero
point calibration is to be realized the first time the device is put
into operation and before any regular operations are carried out.
Zero point calibration is to be carried out using a fluid.
The zero calibration procedure is as follows:
•
Install the sensor as described in the manual.
•
Check to ensure that the sensor is completely filled with
fluid and that there are no gas bubbles in the flow tubes.
•
Set the process conditions such as pressure, temperature
and density.
•
Close the cut-off device behind the sensor.
•
Operate the transmitter in accordance with the instructions
in chapter „Zero point adjustment“ on page 11for the basic
version or chapter „Zero point calibration“ on page 20 for
the version with the control panel.
•
Make sure that sufficient time is allowed for the electronics
to warm up.
•
Allowing fluid to flow through the sensor during the zero
calibration procedure will skew the zero point and result in
false readings.
Startup conditions
The device is not subject to specific startup conditions. However,
pressure surges should be avoided.
Commisioning the
mag-flux
flow probes
In order to be able to calculate the volume flow when using the
mag-flux
flow probes correctly from the measured flow velocity,
the installation requirements must be kept regarding position and
mounting depth correctly.
Transmitter settings must be made as specified in
chapter „Operating the
mag-flux
flow probes with
the
mag-flux M1
” on page 6 to ensure the correct
operation!
Particularly for existing installations after replace-
ments or modifications e.g. tubing diameter.
__
Arbeitsweise und Systemaufbau
Measuring principle
It was back in 1832 that Faraday suggested utilizing the principle
of electrodynamic induction for measuring flow velocities. His
experiments in the Thames, though unsuccessful due to
superimposed polarization effects, are nonetheless regarded as
the first experiment in the field of magnetic-inductive flow
measurement. According to Faraday’s law of electromagnetic
induction, an electrical field E is produced in a conductive liquid
moving through a magnetic field B at a velocity v in accordance
with the vector product E = [v x B].
Fig 2 Principle of the magnetic-inductive flow measurement
Through a meter tube provided with an insulating lining a liquid
flows at velocity v and a flow rate Q, producing a measuring-
circuit voltage Um at the two electrodes at right angles to the di-
rection of flow. The size of this measuring-circuit voltage is pro-
portional to the mean flow velocity and the volume flow rate.
System design
The meter consists of a
mag-flux M1
transmitter and a sensor
e.g. mag-flux series. The device can be used to perform mea-
surements with any liquid, conductive media, providing that the
sensor’s material is suitable for the product being used.
The
mag-flux M1
transmitter generates the inductive current
necessary for the magnetic field and preprocesses the induced
voltage at the electrodes.
