Yokogawa ADMAG CA - Manual (Page 90)

IM 1E8B0-01E
11-3
11. OPERATING PRINCIPLE
A / D
ROM
RAM
EEPROM
LCD
KEY
BRAIN
4-20 mA
OUTPUT
PLUSE
OUTPUT
ALARM
OUT
EXCITER
POWER
SUPPLY
ELECTRODE
PIPE
CPU
COIL
SHIELD CASES
POWER
(2) Circuit features
• Power supply (switching regulator system)
The switching regulator system is a power circuit unique to Yokogawa. Supply
Voltage changes do not affect the converters Yokogawa. Supply voltage changes do
not affect the converters operation because this system not only can be driven by
either AC or DC power but also continuously controls the secondary voltage.
• Excitation system and signal conditioning
There is a problem with an unstable zero point in high-frequency excitation that is
less affected by fluid noise. To resolve this problem, it is necessary to make the rise
of magnetic field faster and have the magnetic field remain constant during signal
sampling. The ADMAG CA stabilizes the zero point by adopting capacitance elec-
trodes and improving.
The signal allows the stable measurement of fluids whose conductivity is very low or
fluids which are stick because the signal is less affected by flow noise.
• Functions
Soft ware engineering actively utilizes the capability of microcomputers to its maxi-
mum. The converter is provided with various functions such as span setting in an
engineering unit, totalization, pulse output, self-diagnosis and others as well as active
use of microcomputer for excitation and signal conditioning.