Det-Tronics MOS H2S Gas Sensor - Manual (Page 23)

95-8532 1.4 21
TROUBLESHOOTING
automatic Diagnostics and fault Messages
The transmitter features self-testing circuitry that
continuously checks for problems that could prevent
proper system response. When power is applied, the
microprocessor automatically tests the unit. If a fault is
detected during this warmup mode, it will be indicated
on the display and must be reset to clear. In the Normal
operating mode, it continuously monitors the input signal
from the sensor to ensure proper functioning.
In the event of a system fault:
The display identifies the nature of the fault using •
a fault message. Refer to Table 8 for an expanded
explanation of the messages.
The normally energized Fault relay (on relay models)
•
is de-energized.
The DC current output drops to less than 1.0 ma.
•
NOTE
The fault message will be shown for about
1.5 seconds out of every 3 seconds. The gas
concentration at the sensor will be displayed
during the remaining time. If more than one fault
should occur, the highest priority fault will be
displayed. (Table 8 lists the faults in order of
priority.)
In the event of an alarm condition and a system
fault both occurring:
In most cases, the first condition that occurs will be •
indicated by the current and relay outputs and on
the display.
The exceptions are “CAL ABORTED” and “SENSOR
•
E.O.L.” faults, which can occur during the calibration
procedure. If an alarm occurs with these faults, the
alarm will over-ride the fault and will be indicated.
prioritized faults
The faults are prioritized, with the highest fault being the
only one displayed (see Table 8 for a prioritized listing).
If an additional fault exists, it will be displayed after the
higher priority fault has been cleared.
Clearing faults
Generally, faults that occur while in the normal mode are
self-clearing once the fault condition has been corrected.
Faults that occur while in the warmup and calibration
modes require a manual reset to clear (using either an
externally connected reset switch or the Cal magnet).
After the fault condition has been corrected, the fault
relay automatically switches to the normal (energized)
state, the DC current output returns to normal, and the
fault message turns off.
CAUTION
The fault detection circuitry does not monitor the
operation of external response equipment or the
wiring to these devices. It is important that these
devices be checked periodically to ensure that
they are operational.
NOTE
The sensor must be periodically inspected and
calibrated following prolonged exposure to
contaminating gases and vapors.
SPARE PARTS
Electronic Module - Specify gas sensor type (MOS •
H
2
S) and with or without optional relay package
when ordering.
Sensors - Specify MOS H
•
2
S, with CSA Approval or
CSA/CENELEC Approval
H
•
2
S Ampoule Calibration Kits
Spare 40 ppm H •
2
S Ampoules
Lubriplate grease for threads •
Other accessories are available. Contact your local •
representative or the factory for information.
DEVICE REPAIR AND RETURN
Prior to returning devices, contact the nearest local
Detector Electronics office so that a Service Order
number can be assigned. A written statement describing
the malfunction must accompany the returned device to
expedite finding the cause of the failure.
Pack the unit properly. Use sufficient packing material
in addition to an antistatic bag or aluminum-backed
cardboard as protection from electrostatic discharge.
Return all equipment transportation prepaid to the factory
in Minneapolis.