Fluke Biomedical 942A-200L-M4 - Manual (Page 43)

Operation
Operation
3
3-3
3.3 Operation
Operation of the UDR consists of operator functions and configuration functions. All operator functions
are performed using the front panel shown in Figures 2-7 or 2-8. Configuration functions are performed
using internal data entry switches and/or jumpers, which are accessible with a partial removal of the UDR
from the mounting enclosure. Calibrations involving trim pots are described in Section 4.
Normal Operation
If the measured radiation field is within the range of the detector during power-up, the CPM value will be
displayed as a three digit number: M.MMEN, where M = 0 to 9 with a single digit exponent N, where N = 0
to 9 and can be either positive or negative. For example, 2.97 x 10
4 would be displayed as 2.97E4. The
bargraph will display the value on the fixed CPM scale and any indicator lights which are on (ON/OFF,
CHECK SOURCE) should be green, providing the operator with a visual indication of normal operation.
WARN/HIGH/RATE Alarms
NOTE
The RATE alarm is an option and is not implemented on
the Model 942A-200L-M4 or 942A-200L-M5.
If the measured radiation field increases above the WARN alarm limit, the WARN alarm indicator will turn
on flashing (amber color), the bargraph will change color to amber, and the WARN alarm relay will de-
activate. If the measured radiation field increases above the HIGH alarm limit, the HIGH alarm indicator
will turn on flashing (red color), the bargraph will change color to red, and the high and rate (also
identified as auxiliary high) alarm relay will de-activate.
NOTE
Normal WARN, and HIGH alarm relay operation is fail-
safe. The relay is normally energized, and de-energized
when the alarm condition is active. Non-failsafe relay
operation for the HIGH, and WARN, alarms is available
as an option at time of purchase.
The UDR can be configured to automatically reset the alarm relays and alarm indicators, or it can hold the
alarm relays energized and flash the alarm indicators until the alarm acknowledge (ALARM ACK)
pushbutton is pressed. If the ALARM ACK pushbutton is pressed while the alarm condition still exists, the
indicators will go to a steady state, and the relays will remain energized until the alarm condition returns
to normal.
Upon resumption of normal operation, the relays and alarm indicators will de-energize. The bargraph
color will always indicate the current status; green for normal, amber for warn, and red for a high alarm.
Front panel pushbuttons labeled HIGH and WARN may be used to display the respective alarm set
points.
Range Alarm
The UDR is provided with three types of Range alarms, Under Range, Over Range and Anti-Jam.
Under Range: If the measured radiation field is below a minimum range of 1.00E1 CPM, the front panel
display will indicate 0.00E0 CPM, the bargraph will extinguish the analog output will be at its low scale
value and the RANGE alarm indicator will illuminate in red. The minimum range is factory set to 10 CPM.
When the measured radiation field increases into the range of the detector, the RANGE alarm indicator
will extinguish and normal operation will begin. There is no relay output associated with the under range
alarm.