Endress+Hauser magphant, Operating Manual

Page: 5 / 24

1. System description
1.1 Areas of application
The Magphant flow monitor provides the plant system with the information needed on
flowrate in the piping. The magnetic-inductive measuring principle determines the
flow velocity of the conductive liquid at the tip of the sensor. Exceeding the preset
switchpoint (limit value) is indicated by a relay contact. An analogue 4...20 mA signal
proportional to the flow is also available for monitoring the flowrate at the same time.
The Magphant is ideal for process protection and monitoring.
1.2 Measuring principle
In accordance with Faradays law of magnetic induction, a voltage is induced in a con-
ductor that is moved through a magnetic field. In the electromagnetic principle of
measurement the flowing fluid represents the moving conductor. The induced voltage
is proportional to the flow velocity and is fed to the measuring amplifier by a pair of
electrodes.
Microprocessor-controlled electronics, with a stable zero-point, convert the voltage
into an analogue 4...20-mA output signal.
U
e
= B x L x v = induced voltage
B = magnetic induction (magnetic field)
L = distance between electrodes
v = flow velocity at the tip of the sensor
b
a025
y
0
8
Magnetic lines of force
B
Electrodes
Magnetic core
Exciter coil
Sensor
L
U
e
v
Fig. 1:
Measuring principle of electro-
magnetic flow measurement
Magphant 1. System description
Hauser 5