Installation and Operation Manual - COMTEC
®
6000 ATEX GasEx
Troubleshooting
Doc.-ID: COMGAS_11022020_EN
69
7
Troubleshooting
Unsteady, widely varying measuring value (O
2
)
Possible reasons
Procedure
Intermittent contact caused by wire breakage
Eliminate bad/loose contact
Intermittent contact inside the probe - internal mV
connection
Broken filter element
Visual inspection by dismounting the probe
Wrongly installed V-shield
Probe has been installed without filter head
O
2
display remains at the end of the measuring range or is higher than expected
Possible reasons
Procedure
Leakages at the measuring probe or at the O
2
sensor flange
seal.
Check all flanges and screw connections for tightness.
Exchange O
2
sensor or replace O
2
sensor flange seal. In
case of a leakage in the area of the O
2
sensor, the O
2
sensor must be exchanged.
Probe flange not welded gas tight.
Tighten flange bolts with required torque, possible renew
the gasket.
Local Displays correct, Output not correct
Possible reasons
Procedure
Electronic unit is defective
Check measuring range. Check whether the current value
is outside the measuring range
Measure the mA output on the strip terminal.
O
2
Display Indicates 0 %, although the Process Operation Mode expects a higher O
2
Value
Possible reasons
Procedure
Measuring probe heater defective (resistance must be
approx. 37.5-47.5 Ohm, disconnect probe and check).
Check the measuring cell temperature (set value
800°C/1472°F. A lower temperature could have the effect
of showing a value of 0 %.
Thermocouple defective (check resistance, approx. 2-80
Ohm).
Check the mV value of the O2 measuring cell
Fuse for heater voltage defective.
Replace the fuse
Cable short circuit. Electronic units input defective. Wire
break
Check wiring. Measure probe cable.
Transformer (230/115V) is defective
Check the fuse
There is no mV contact in the probe (measuring signal wire)
or it is interrupted.
Check probe inner part for good contact.
Combustibles in the flue gas.
Check whether the probe reacts to test gas. If it does,
there may be a high proportion of combustibles in the flue
gas. In this case, there are reducing conditions at the
probe sensor, which reduce the oxygen content at the
sensor surface.
Caution: Explosion hazard!
Measuring cell defective.
Replace the sensor.
