KROHNE IFC 090 Converter EN - Manual (Page 60)

7/9
Always switch off power source before opening the housing !
Required measuring instruments and tools
-
Special wrench to unscrew the covers, a crosstip screwdriver
- Ohmmeter with at least 6 V range
or AC voltage/resistance measuring bridge.
Note: Accurate measurements in the area of the electrodes can only be obtained with an
AC voltage/resistance bridge. Also, the measured resistance is very heavily dependent on
the electrical conductivity of the liquid product.
Preparatory work
•
Switch off power source.
• Unscrew covers from terminal and electronic
compartments using the special wrench.
If provided, remove the display unit. For this
purpose, detach the two screws R and fold
display unit to the side, see figure in Sect. 8.5.
• Pull off the blue 9-pin plug from the amplifier
PCB, see figure in Sect. 8.9, field power
supply (Pin 7+8) and signal cables
(Pin 1, 2, 3, 4 + 5)
• Completely fill the measuring tube of the
flowmeter with the process liquid.
7.5 Test of primary head
Action Typical result Incorrect result =
Resistance measurement flowmeter defective,
at the blue 9-pin plug return to factory for repair,
refer to last but one page !
1 Measure resistance 30 - 150
Ω
if lower:
between wires interwinding fault
7 and 8.
if higher:
wire break
2 Measure > 10 M
Ω
if lower:
resistance between interwinding fault to PE
U-clamp terminal or FE.
in terminal compartment
(PE protective conductor
or FE functional ground)
and wires 7 and 8
3 Measure resistance 1 k
Ω
- 1 M
Ω
if lower: drain measuring
between wires 1 and 3 (see “Note” above). tube and repeat
and between 1 and 4 Both values should be measurement; if still
(same measuring lead approx. equal. too low, short-circuit in
always on wire 1 ! ) electrode wires.
if higher: break in
electrode wires or
electrodes
contaminated.
Values not equal:
break in electrode
wires or electrodes
contaminated.
Jacks X1 and X4 on amplifier PCB,
see Sect. 8.9
Blue 9-pin plug
(connection to primary head)
unassigned
X1 X4
7 8 1 2 3 4 5