Hach Sigma 950, Инструкция по эксплуатации инструмента

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Troubleshooting
Troubleshooting the Submerged Area/Velocity Sensor
Problem Cause Solution
RS485 Time
Out—Unit did not
receive data with
specified time.
CPU board is having trouble communicating
with the Velocity board.
Wait a few minutes and see if the condition
disappears. If it continues there is a problem with the
velocity, ultrasonic, or CPU board.
Logging intervals are 1 or 2 minutes, conditions
are poor, and the problem continues
indefinitely.
Increase the logging interval to allow more time to
capture the signal.
Difficulty receiving a velocity reading. Indicates an internal problem.
Zero Velocity or
Velocity Drop Outs
Sensor is covered with sediment Clean the sensor.
Low particulate levels in the channel.
Stir up the water in front of the probe and watch the
signal strength. If the signal starts to vary this may
be an indication of low particulate in the channel.
Unusual events occurred.
Check the event log for unusual events that occurred
around the time of the velocity problems.
Radio Interference in the area. Move the unit to a different location.
Loss of Area
Velocity as Primary
Device
Blown fuse on the CPU board—the prompt was
there and then disappears.
Replace the fuse, located in position F1 under the
gray ribbon cable that connects at position J1 (see
section
9.4 on page 75 ).
Inaccurate Velocities
Obstructions
Obstructions should be a minimum of 5 pipe
diameters downstream and 10 diameters upstream.
Eddies and waves returning flow back into the
pipe could be causing incorrect velocities.
—
The invert has an unusual construction such as
a rounded section in the middle of the invert or
drops that may cause a draw-down effect.
Relocate the probe.
Mounting band and probe are not positioned
correctly—it was working fine, then had trouble. Check the mounting band and probe to see if it
slipped out of poisiton.
Troubleshooting the Submerged Depth Only Sensor
Problem Cause Solution
Depth readings are inaccurate or
no change in depth readings.
Incorrect calibration.
Check to see if the unit is calibrated.
Re-calibrate the sensor to the unit.
Sensors have been swapped between
units and where not re-calibrated. Sensors must be re-calibrated each time it is
placed on another unit.
Desiccant is clogged. Replace if the desiccant has turned pink.
Depth is trending upward because of
water or debris in the atmospheric
reference tube.
Clean and re-calibrate.
Depth is trending downward due to debris
in the diaphragm. Remove the plate and carefully clean out the
debris.
Silt is covering the sensor. Clean sensor.
Excessive Debris Collection Improper use of sensor mounting band.
To reduce the likelihood of debris collecting on
the cable and mounting band, route the cable
along the edge of the band and fasten the
cable to the mounting band with nylon wire
ties. The cable should exit the tied area at, or
near, the top of the pipe to keep it out of the
flow stream.
Submerged Depth readings are
inaccurate or no change in depth
readings.
Improper Calibration.
Check to see if the unit is calibrated.
Re-calibrate the sensor.