Kistler-Morse KM Microcell Bolt-On - Manual (Page 34)

EXPLANATION
Fluctuations in readings can be caused by short to
ground.
Problem Likely to be Noticed
Shortly after initial installation
or on system that
previously functioned correctly.
Solution
Using a Digital Multimeter (DMM) or ohmmeter,
check for shorts to ground:
1. Set meter resistance scale to
accommodate maximum measured range.
2. Disconnect junction box wires from
signal processor.
3. With one lead to earth ground and other
lead to white wire, check resistance on
disconnected junction box wires:
A. If reading is less than infinite
(i.e., there is resistance), a short is
indicated; proceed to Step 4 to identify
location.
B. If no short is indicated, investigate
other explanations for problem.
4. Starting with junction box closest to
signal processor in daisy chain, disconnect
wires connecting junction box to the other
junction boxes. With one lead to earth
ground and other lead to white wire,
check resistance on wires leading from
junction box:
A. If reading is less than infinite (i.e., there
is resistance), short is indicated;
proceed to Step 5 to further identify
location.
B. If no short is indicated, proceed to next
junction box in daisy chain. Disconnect
wires connecting it to other junction
boxes and check resistances. Repeat
for each junction box down chain until
short is located; proceed to Step 5.
5. Disconnect Microcell™ wires for one
Microcell™ from above-identified junction
box. With one lead to earth ground and
other lead to white wire, check resistance
on disconnected Microcell™ wires:
A. If reading is less than infinite (i.e.,
there is resistance), short is indicated.
Replace shorted Microcell™.
B. If no short is indicated, disconnect next
Microcell™ wires from junction box and
check resistances. Repeat for each
Microcell™ wired to junction box until
short is located. Replace the shorted
Microcell™.
EXPLANATION
Fluctuations in readings can be caused by
problems with signal processor.
Problem Likely to be Noticed
Shortly after initial installation or on system that
previously functioned correctly.
Solution
Check signal processor excitation voltage and
incoming AC voltage for accuracy and stability
(refer to signal processor manual).
PROBLEM 2. REPEATABLE DRIFT
OVER A 24-HOUR PERIOD.
EXPLANATION
Periodic drift is most likely caused by thermal
expansion of vessel or vessel’s supports due to
the sun’s radiation or a vessel’s response to its
own heating cycles.
Problem Likely to be Noticed
Shortly after initial installation or on system that
previously functioned correctly in cool or
overcast weather.
Solution
1. If periodic drift is outside specifications
(Appendix A), contact Kistler-Morse ® .
2. For Microcells™ installed on vertical
column legs, if drift is within specifications
but you want to reduce it further, install
Kistler-Morse ® insulation. Contact
Kistler-Morse ® to order insulation.
Installation details are included in
Chapter 3 (Microcell™ Installation on
Vertical Column Legs).
3. If keeping long-term records, take readings
at the same time each day to minimize
error.
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