KROHNE VFM 1091 - Manual (Page 27)

It is assumed in this section that flowmeter has already been
installed. (for installation details refer Sect. 2+3)
Following are some trouble shooting hints.
SYMPTOMS: Display is blank.
· DC Supply voltage (between term. 5/6) is not
available (voltage range 12-36 Vd.c).
· Supply connected with reverse polarity
Important: Ensure that the screw threads of the covers on
the electronics and connection compartments are well
greased at all times
· Electronics faulty
SYMPTOM: Current output is not proper.
· Check current output electronics (refer Sect.7.2.3)
· Check that current output loop resistance is less
than Rmax specified by Section 3.3.2
SYMPTOM: Pulse output is incorrect
· Check the Pulse output electronics (refer Sect.7.2.4)
· Check programming of pulse output. (Functions
Fct1.3.x )
· Check that pulse output is not overloaded. For load
ratings of pulse output refer Sect.3.3.3.
SYMPTOM: Non zero flow indicated when no
actual flow in the pipe.
· Mains interference due to improper earthing.
The protective earth PE terminal should be
properly grounded.
· Excessive mechanical vibration in the pipe.
If so, support the pipeline near the flowmeter
perpendicular to both the axis of pipe and the axis
of bluff body.
SYMPTOM: Flowrate indicated is 0.0 even with flow in
the pipe.
· Vortex sensor cable disconnected or not properly
connected.
· Flow sensor faulty – some checks are given in
Sect.7.1.1
· Electronics faulty (preamplifier)
· Fct. 3.3.4 Gain too low: Set gain to value of 5 or greater &
check.
SYMPTOM: Fatal error INV. CONFIG (invalid
configuration)
· Configuration data in the non-volatile memory is
inadvertently corrupted. Go to the programming
mode and recheck (reprogram, if necessary) all
the settings. If error persists contact Forbes Marshall service.
SYMPTOM: Display contrast is progressively Fading.
· Never expose display directly to the sunlight!
Install a sunshade if necessary.
SYMPTOM: Flow indicated responds to changes in flow
but indicated value does not correspond to actual flow
rate.
8. Trouble shooting hints
· Check programming of Fct.3.1.2 K-Factor which should be
same as on the nameplate.
· Meter not properly centered on the pipeline. The axis of
meter bore should be aligned with that of pipe.
· Gaskets at the meter are protruding into pipe bore.
Gaskets must not project into effective cross-
section of the pipe.
· Irregularities on the surface of the pipe bore.
The pipe bore should be free from irregularities
at the welded joints, dirt, deposits and excessive
surface roughness.
· Vortex signal is falsified due to a bi-phase medium.
Bi-phase media are not permitted. Use a moisture
separator for wet steam applications to remove
moisture droplets from the steam. Use suitable
filters
in gas applications to remove solid
particles from the flowing gas.
· Incorrect angular position of the meter
Refer to Sect.2.1 (1) for allowable mounting positions.
· Insufficient upstream / downstream pipe lengths.
Check that upstream / downstream pipe lengths are of
correct minimum length as given in Sect.2. 1(3).
· Check the flow direction & direction of arrow on
the primary!
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