Fluke Biomedical 942A-200L-M4 User Manual
Page 44
942A-200L-M4 & 942A-200L-M5 UDR
Operator Manual
3-4
Over Range: If the measured radiation field goes above the Overrange set point, the RANGE alarm
indicator will illuminate, the bar graph will illuminate in red, full scale, the Warn alarm LED will turn on,
flashing, the Warn relay will change state, the High alarm relay will turn on, flashing, the High alarm relay
will change state, the analog output will be at its full scale value and the front panel display will indicate
EEEEE. The maximum range of the detector is used to determine the overrange set point. When the
measured radiation field returns within the maximum operating range of the detector and the condition is
acknowledged, the RANGE alarm indicator will extinguish, the radiation alarms will clear, and normal
operation will resume.
Anti Jam: In the event the detector output exceeds the electronic Anti-jam circuit trip level, the Anti-jam
fuse will open the FAIL alarm indicator will illuminate, the FAIL relay will change state, the RANGE alarm
indicator will illuminate, the detector high voltage will shut down, the bar graph will illuminate in red, full
scale, the analog output will be at its full scale value and the front panel display will indicate EEEEE. In
most cases, as the radiation value increases, the WARN and HIGH alarm indicators will also be turn on,
flashing and the WARN and HIGH alarm relays will also have changed state. The Anti-jam condition is
provided to ensure that if the radiation level exceeds the range of the detector, and the detector output
drops to a steady DC level, the UDR display will not drop to a value less than full scale. In our design, this
is accomplished by forcing the digital display to display an error message, EEEEE. In addition, the
detector high voltage supply is also shut down to protect the detector from damage and the Anti-jam fuse
is blown, locking the UDR in the Anti-jam condition. To recover from an Anti-jam trip, once the radiation
has decreased, the following steps are required:
Anti-jam
Recovery:
Turn UDR AC power OFF
Remove Anti-jam fuse F1 (1/20 amp, plug-in type)
Replace Anti-jam fuse
Turn AC power ON
If the Anti-jam fuse is in the bypassed, or test condition (i.e. UDR Main Board jumper JP6 is in the 2-3
position), the Anti-jam fuse will not be opened, and the unit may be returned to normal operation by
cycling the AC power ON and OFF.
The difference between the Overrange state and the Anti-jam state are as follows:
Description Overrange: Anti-jam
Display
Range LED
FAIL LED
FAIL Relay
High Voltage
EEEEE
ON
OFF
Normal
Normal
EEEEE
ON
ON
Tripped (de-energized)
Turned off
Bar Graph
Analog Output
ON, RED
Full Scale
ON, RED
Full Scale
Recovery
(Once
radiation field
is normal)
Press
Acknowledge *
Power Down,
Replace Anti-jam fuse
Power back up *
* = Input must be below the Over range set point