Yokogawa AXFA14G/C - Manual (Page 15)

IM 1E6K2-E
4-19-7
4. OPERATION
4.8.2 Checking Procedure
(1) Standard dual frequency excitation
Change Function.
Turn on tne Junction box power.
Span setting
Changing the setting of AXF AMPLIFIER UNIT
Check the zero point
Set the “C20 Measure Mode” to “Standard DF”. (Before changing the mode, write down
the previous value)
Set the meter factors of “C21 Low MF” and “C22 High MF” to 1.0000. (Before changing the
settings, record the previous values.)
Slide the AM012 FUNCTION switch to the ADMAG posiotion.
Two excitation lamps will flash alternately at regular intervals. (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 converter is set to "mm". The flow velocity can be checked with
"C44 Velocity Check" parameter of the converter.
Turn the output knob of AM012 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
Return the ADMAG AXF AMPLIFIER UNIT set values to their initial values.
Return the "C20 Measure Mode" to the initial value which was previonsly recorded.
Return the two meter factors of “C21 Low MF” and “C22 High MF” to the value recorded before
the change.
Turn off the Junction box power.
Turn the output knob to 25%, 50%, 75% and 100% in turn and check the indicated values. (Subtract
the zero point value from the indicated value to check the output accuracy.) Set the knob to CHECK
to check the common mode noise rejection. (See Note 3 below)
Remove the power supply and ground cables from the AM012.
Remove the signal and excitation cables from the AM012.
Remove the amplifier unit from the Junction box .
Install the amplifier into the converter.
Loosen the fixing screws, disengage the connectors, then remove the amplifier unit.
(1) To install the amplifier assembly, follow the procedures used to remove it in the reverse order.
(Refer to Figure 4.8.2)
(2) Replace the unit by pushing it in, taking care not to damage the amplifier mounting connectors on
the circuit board.
(3) Carefully connect wiring connectors 1 and 2 to the amplifier unit, making sure that the
connectors’ directions are correct. Let wiring connector 2 pass along the amplifier side of the rod.
(4) Tighten the three mounting screws while holding the unit with your hand.
(5) Screw in the cover, taking care not to entangle the cables of the wiring connectors.
(6) Tighten cover locking screw.
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 AXFA14 or AXF integral flowmeter, 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 AXFA14 or AXF
integral flowmeter.
Note 3 : A common mode noise signal equivalent to a set value with the span-setting dial is output from the AM012.