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INSTRUCTION MANUAL 10DX3111A&G Sizes 14 - 24 Inches
This electrode voltage is the summation of all incremental voltages developed within each liquid
particle that passes under the influence of the magnetic field.
This may be expressed mathematically as:
(Equation #1)
where:
E
= induced electrode voltage
s
B = magnetic field strength
D = meter pipe diameter
α = dimensionless constant
V = liquid velocity
Thus, the metered liquid constitutes a continuous series of conductive liquid disks moving through a
magnetic field. The more rapid the rate of liquid flow, the greater the instantaneous value of signal
voltage as monitored at the meter electrodes.
4.1.2 Magnet Coil Drive Circuits
In many conventional Magnetic Flowmeters the integral magnet coils are driven directly by the
customer's 50/60 Hz power service. Notably, however, the design of the ABB Automation Series
3000 Magnetic Flowmeter uses magnet drive circuits which are alternately energized
bi-directionally at a low frequency rate as commanded by the associated Converter/Driver electron-
ics.
4.1.3 Volumetric Flow Rate Measurement
The ABB Automation Magnetic Flowmeter is a volumetric flow rate measuring instrument. This can
be shown by substituting the physical equivalent of liquid velocity into equation #1 as follows:
(Equation #2)
Substituting for V in equation #1
and solving for Q:
Since B = β E
r
and since α, D and β are constant:
4-2
1
E s =
BDV
α
Q = 4 Q
V =
πD
2
A
4 Q
E s = 1 BD
2
α
πD
∴ Q = παD
2
• E
s
4
B
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