ATI
Q45D-ODO Optical D.O. System
Part 9– Troubleshooting
O & M Manual
Revision C (7/09)
60 -
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. The reading should
be initially stable and then fall very slowly in a smooth fashion
as the powered sensor depletes oxygen in the static sample
directly at the sensor face.
7. On relay based systems, check the load that is connected to the
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 driving these types of loads when they are
switched on an off, the relay wiring placement can result in
electrical interference for other devices. This can be quickly
resolved by moving wiring, or by adding very inexpensive
snubbers (such As Quencharcs) to the load.
8. Carefully examine any junction box connections for loose wiring
or bad wire stripping. If possible, connect the sensor directly to
the analyzer for testing.
9. Check sensor for fouling. Look closely for signs of grease or oil
which may be present.
9.3
Analyzer Tests
1. Disconnect power and completely disconnect all output wiring
coming from the analyzer. Remove sensor wiring, relay wiring,
and analog output wiring. Re-apply power to the analyzer.
Verify proper voltage (115 or 230 VAC) is present on the
incoming power strip of the analyzer, and that the analyzer
power label matches the proper voltage value.
2. If analyzer does not appear to power up (no display), remove
power and check removable fuse for continuity with a DVM.
