21 Instruction Manual
Testing of Flowtube
Always switch off power source before connecting and disconnecting cables.
Check Coil Voltage
Remove flowtube terminal lid. Use AC
voltmeter to measure voltage at the
coil terminals of flowtube.
Reading > 3V?
Check signal converter fuse etc
FUSE(5X20mm, 230v, 500mA)
Switch off signal converter.
Disconnect wires from coil term. at signal
converter. Switch on and measure AC voltage
at the two coil terminals of the converter COIL-
COIL.
No
No
Yes
No
Switch off signal converter.
At the flowtube terminals
disconnect E1, Earth & E2. At the
flowtube measure the resistance
between E1 - EARTH and E2 -
EARTH on the flowtube.
Are measured resistance approx.
equal?
Electrodes contaminated. Clean!
Electrodes leaking. Return flowtube for
Break or short-circuit in field coil cable.
Correct problem.
Yes
Check insulation.
At Beta signal converter
disconnect electrode & coil wires.
Test insulation with cable and
flowtube connected. SCRN1-
EARTH, SCRN2-EARTH, COIL-
Check coil resistance.
Disconnect cable at flowtube.
Measure the resistance of COIL-
COIL.
Is it approx. 40 ohms?
Flowtube in order
Yes
Yes
Check insulation.
Disconnect cable from flowtube. Test insulation
of tube only. SCRN1-EARTH, SCRN2-EARTH,
COIL-EARTH, COIL-EARTH > 20 Mohm?
Cable has ground fault.
Replace !
Field coils faulty
Flowtube defective! Return for repair
No
Yes
No
Yes
No
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