Measuring principleFollowing Faraday's law of magnetic induction, a voltage is induced in a conductor moving through a
magnetic field.
In the electromagnetic measuring principle, the flowing fluid is the moving conductor.
The voltage induced is proportional to the flow velocity and is supplied to the amplifier by means of
two measuring electrodes. The flow volume is calculated by means of the pipe cross-sectional area. The
DC magnetic field is created through a switched direct current of alternating polarity.
Ue = B · L · v
Q = A · v
UeInduced voltage
B Magnetic induction (magnetic field)
LElectrode spacing
vFlow velocity
QVolume flow
APipe cross-section
ICurrent strength
Measuring systemThe measuring system consists of a transmitter and a sensor.
Two versions are available:
• Compact version: Transmitter and sensor form a mechanical unit.
• Remote version: Sensor is mounted separate from the transmitter.
Connecting the transmitter, cable cross-section max. 2.5 mm2 (14 AWG)
aElectronics compartment cover
bPower supply cable
cGround terminal for protective ground
dTerminal connector for power supply cable
eSignal cable
fGround terminal for signal cable
gTerminal connector for signal cable
hService connector
iGround terminal for potential equalization
Potential equalizationPerfect measurement can only be guaranteed if the fluid and sensor are on the same electric potential.
This is ensured by the two ground disks of the sensor.
The following should also be taken into consideration for potential equalization:
• Internal grounding concepts in the company
• Operating conditions, such as the material/grounding of the pipes, cathodic protection etc. (see
table)
Standard
Operating conditionsPotential equalization
When using the measuring device in a:
• Metal, grounded pipe
• Plastic pipe
• Pipe with insulating lining
Potential equalization takes place via the ground terminal
of the transmitter (standard situation).
Note!
!
When installing in metal pipes, we recommend you connect
the ground terminal of the transmitter housing with the
piping.
Via the ground terminal of the transmitter
A0010702
Special cases for Promag D as wafer version
Operating conditionsPotential equalization
When using the measuring device in a:
• Metal pipe that is not grounded
This connection method also applies in situations where:
• Customary potential equalization cannot be ensured
• Excessively high equalizing currents can be expected
Potential equalization takes place via the ground terminal
of the transmitter and the two pipe flanges.
Here, the ground cable (copper wire, 6 mm
mounted directly on the conductive flange coating with
flange screws.
When using the measuring device in a:
• Pipe with a cathodic protection unit
The device is installed potential-free in the pipe.
Only the two flanges of the pipe are connected with a
ground cable (copper wire, 6 mm
2
ground cable is mounted directly on the conductive flange
coating with flange screws.
Note the following when installing:
• The applicable regulations regarding potential-free
installation must be observed.
•There should be no electrically conductive connection
between the pipe and the device.
• The mounting material must withstand the applicable
torques.
2
/ 10 AWG) is
/ 10 AWG). Here, the
Via the ground terminal of the transmitter and the
flanges of the pipe (ground cable: copper wire at least
2
/ 10 AWG)
6mm
Potential equalization and cathodic protection (ground
cable: copper wire at least 6 mm
Operation in zones of severe electrical interference
The measuring device complies with the general safety requirements in accordance with EN 61010-1,
the EMC requirements of IEC/EN 61326 and NAMUR Recommendation NE 21.
Caution!
"
Grounding is by means of the ground terminals provided for the purpose inside the connection
housing.
Ensure that the stripped and twisted lengths of cable shield to the ground terminal are as short as
possible.
8Endress+Hauser
Proline Promag 10D
2.5
[%]
2.0
1.5
1.0
0.5
0
0.5 %
0
1
246810 [m/s]
v
5101520253032 [ft/s]0
Performance characteristics
Reference operating
conditions
• Error limits following DIN EN 29104, future ISO 20456
• Water, typically +4 to +35°C (+39 to +95 °F); 2 to 6 bar (29 to 87 psi)
• Specification as per calibration protocol ± 5°C (± 41 °F) and ± 2 bar (± 29 psi)
• Data on the measured error based on accredited calibration rigs traced back to ISO 17025
Maximum measured error• Current output: also typically ±5 μA