Fluke Biomedical 945A - Manual (Page 27)

Operation / Functions
Operation of the 946A-200 UDR consists of operator functions and configuration functions. All operator
functions are performed using the front panel. Configuration functions are performed using internal
switches and/or jumpers which are accessible with a partial removal of the UDR from the mounting
enclosure.
Normal Operation
If the measured radiation field is within the range of the detector during power-up, the mR/h, R/h, or kR/h
value will be displayed as a three digit number with a floating decimal point (i.e. .XXX mR/h). The
bargraph will display the value of radiation, with a resolution of three segments per decade, over the
range of the detector or eight decades. The bargraph should be green, providing the operator with a
visual indication of normal operation. All other indicator LEDs should be off. In very low background
environments (< 0.1 mR/h), the range indicator LED may be illuminated.
WARN/HIGH Alarms
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 alarm relay will de-
activate.
NOTE
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 by removing
JP3-3, or it can hold the alarm relays energized and flash the alarm indicators until the alarm
acknowledge (ALARM ACK) push-button is pressed. If the ALARM ACK push-button 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 can be used to display the respective alarm set points.
Range Alarm
If the measured radiation field is below the Underrange setpoint, the front panel display will indicate 0.00
mR/h, and the RANGE alarm indicator will illuminate in red, the bargraph will indicate the actual radiation
value, and the analog output will be set to zero. The minimum range is an adjustable setpoint and is
defaulted to 1.00-1 mR/h. When the measured radiation field increases into the range of the detector, the
RANGE alarm indicator will extinguish and normal operation will continue.
If the measured radiation field goes above the overrange set point, the RANGE alarm indicator will
illuminate and the front panel display will indicate EEEEE, the bargraph will illuminated in RED, and the
analog output will be set to full scale. The maximum range of the detector is used is determine by 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 and normal
operation will resume.
4-3