Yokogawa ADMAG AXW - Manual (Page 27)

<5. MAINTENANCE>
5-2
IM 01E25D11-01EN
5.2 Regular Inspection Items
(1) Inspection of moisture-proofing inside the
terminal box: Once/year
(2) Retightening of piping joint screws: About
twice/year
(3) Inspection of electrodes and lining (in case
of adhesive and/or abrasive fluids, etc.)
Determine the period of regular inspection as
necessary.
5.3 Excitation Coil and
Insulation Resistance Check
WARNING
• Before checking of the excitation coil and the
insulation resistance, be sure that the power
supply for AXFA11 converter has been turned
off.
• Before checking, be sure to disconnect the
cables from the terminals of the remote
flowtube.
(1) Excitation Coil Check
Check that there is continuity between terminals
EX1 and EX2 in the terminal box. If there is no
continuity, the coils may be broken and replacement
or repair of the flowtube is necessary. The coil
resistance is designed to be 150 Ω or less. If it is
not, this may be an abnormal condition. Consult
Yokogawa’s sales or service offices.
(2) Insulation Resistance Check
Check the insulation resistances in the terminal
box in accordance with the tables below. If any
of them falls below the values listed in the tables,
consult Yokogawa’s sales or service offices for
investigation. If the insulation resistance cannot be
restored, replacement or repair of the flowtube is
needed. In case of submersible type flowmeters,
undo the wiring connection on the converter side
and measure resistance at the cable terminals.
Coil Circuit
Checking is possible even if the pipe is filled with
fluid.
Test Terminals Test Voltage Specification
Between
terminals
EX1 and C
500 V DC (Use an
insulation
tester or the
equivalent.)
1 MΩ or more
Signal Circuit
Before testing, be sure to empty and dry the interior
of the pipe, checking that there is no adhesive
material. Also undo the wiring connection on the
converter side before testing.
Test Terminals Test Voltage Specification
Between
terminals
A and C
Between
terminals
B and C
500 V DC (Use an
insulation
tester or the
equivalent.)
100 MΩ or
more for each