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O&M Manual
Rev-D (11/19)
Part 9 – Troubleshooting
9.1
General
The information included in this section is intended to be used in an attempt to quickly resolve an
operational problem with the system. During any troubleshooting process, it will save the most
time if the operator can first determine if the problem is related to the analyzer, sensor, or some
external source. Therefore, this section is organized from the approach of excluding any likely
external sources, isolating the analyzer, and finally isolating the sensor. If these procedures still
do not resolve the operational problems, any results the operator may have noted here will be
very helpful when discussing the problem with the factory technical support group.
9.2
External Sources of Problems
To begin this process, review the connections of the system to all external connections.
1. Verify the analyzer is earth grounded. For all configurations of the analyzer, an earth
ground connection MUST be present for the shielding systems in the electronics to
be active. Grounded conduit provides no earth connection to the plastic enclosure,
so an earth ground wiring connection must be made at the power input terminal strip.
Use the special “shield terminal” stub on the power supply board for optimum sensor
cable shield grounding.
2. Verify the proper power input is present. Check instrument label to verify your unit is
either 100-240 VAC or 12-24 VDC.
3. Verify the loads on any 4-20 mA outputs do not exceed the limits in the Instrument
Specifications. During troubleshooting, it is many times helpful to disconnect all
these outputs and place wire-shorts across the terminals in the instrument to isolate
the system and evaluate any problems which may be coming down the analog output
connections.
4. Do not run sensor cables or analog output wiring in the same conduits as power
wiring. If low voltage signal cables must come near power wiring, cross them at 90°
to minimize coupling.
5. If rigid conduit has been run directly to the Q46 enclosure, check for signs that
moisture has followed conduit into the enclosure.
6. Check for ground loops. Although the sensor is electrically isolated from the process
water, high frequency sources of electrical noise may still cause erratic behavior in
extreme conditions. If readings are very erratic after wiring has been checked, check
for a possible AC ground loop by temporarily placing the sensor into a bucket of
water.
7. Check the load connected to relay contacts. Verify the load is within the contact
rating of the relays. Relay contacts which have been used for higher power AC
current loads may become unsuitable for very low signal DC loads later on because a
small amount of pitting can form on the contacts. If the load is highly inductive
(solenoids, motor starters, large aux relays), note that the contact rating will be de-
rated to a lower level. Also, due to the large amount of energy present in circuits
