Yokogawa AXFA14G/C - Manual (Page 11)

IM 1E6K2-E
4-19-3
4. OPERATION
(2) Enhanced dual frequency excitation
When the AXFA11 is used in combination with the AXF flowtube which supports the
enhanced dual frequency excitation (optional code HF1 or HF2), the calibration of that
excitation is necessary.
Change the AXFA11 set values.
Turn the AXFA11 power ON.
Span set on the AM012.
Set the “C30 Select Flow Tube” to “Calibrator”
Set the “C20 Measure Mode” to “Enhanced DF”. (Before changing the mode, write down
the previous value)
Set both the “C23 Low MF (EDF)” and “C24 High MF (EDF)” meter factors to 1.0000. (Before
changing the meter factors, write down the previous values.)
See Section 4.7.3, “Meter Factor Setting.”
Two excitation lamps will flash alternately. (See Note 1 below)
After turning ON the power, let the instrument warm up for at least three minutes.
Set the flow velocity of the span with the AM012 span dial. Firstly, be sure to confirm that the "C31
Nominal Size Unit" parameter of AXFA11 is set to "mm". The flow velocity(m/s) can be checked
with "C44 Velocity Check" parameter of AXFA11.
Confirm AM012 FUNCTION.
Check the zero point.
Confirm the AM012 FUNCTION switch to the “ADMAG” position.
Set the output (%) knob to 0% to check the zero point. To check the span accurately, record the
indicated value. (See Note 2 below)
Check the span and output accuracy.
Turn the output (%) knob to 25%, 50%, 75% and 100% in turn to check the indicated values.
(Subtract the zero point value from the indicated value to check the output accuracy.) When the
knob is set to CHECK, common mode noise rejection can be checked (See Note 3 below).
Return the AXFA11 set values to their initial values.
Return the C30 Select Flow Tube to “ADMAG AXF”
Return the "C20 Measure Mode" to the initial value which was previously recorded.
Return both the “C23 Low MF (EDF)” and “C24 High MF (EDF)” meter factors to their initial
values which were previously recorded.
Turn the AXFA11 power OFF.
Remove the power supply and ground cords from the AM012.
Remove the signal and excitation cables from the AM012.
Connect the AXFA11 signal and excitation cables
End
Note 1 : If no exciting current flows, the two excitation lamps do not flash correctly.
Note 2 : When the zero readjustment is available (i.e. the flowtube has been filled with fluid and the fluid
velocity is completely zero) after checking of AXFA11, it is convenient to carry out zero adjustment
instead of subtraction the zero point value.
In case that zero readjustment is not available, do not carry out zero adjustment of AXFA11.
Note 3 : A common mode noise signal equivalent to a set value with the span-setting dial is output from the
AM012.
Set following parameters before wiring AXFA11
to AM012.