Normal Service
Gem-5 User’s Manual 53
Following each background update, the background rate is compared to the low count
rate alarm setting. In addition, the High Voltage is checked and the HV out of range
error is set if the out of range condition is detected two updates in a row. A Detector
Fault condition is checked when reading the detector counters or HV. This could
occur if a detector ID DIP switch is set incorrectly or a cable becomes disconnected.
The unit will go out of service if any of these faults occurs. If the background
exceeds the high background rate setting, then the monitor goes out of service or
shows “High Background” on all subsequent screens, depending on how the unit has
been set up (see F4 – Out of Service Causes setup screen).
The background history for all detectors is stored in the Background Data Log. In
addition, the background history for the previous 1080 updates can be reviewed in
Service mode using the F3 – Background History screen.
When an approaching user activates the approach sensor, the background counts
currently being collected are discarded and the monitor goes to Ready mode,
displaying and annunciating “Ready”.
READY Mode
Activation of the approach sensor places the monitor in Ready mode, which is
displayed on the display screen and announced through speakers. This informs the
user that the unit is operational and ready to monitor. The text color is usually cyan,
however this changes to yellow if the monitor is in Conditional Service (see F4 –
Faults screen). The audible “READY” announcement can be suppressed, if desired,
in the F6 – Operation Voice & Screen menu. This is recommended if several
monitors are located where cross traffic can trigger the approach sensors.
The background update routine stops to prevent changes in the ambient background
level influenced by persons or things which can artificially lower or raise it. This
might occur if an occupant is contaminated or is shielding the detectors or if a person
nearby is carrying a radiation source.
As shown in Figure 24, the Ready screen displays a clock and the model type, as well
as the version number and compilation date of the installed software. This screen
also displays the oldest calibration date for an individual detector below the model
type line; if any detector does not have a valid calibration date (for example, it is
using the default value) then no calibration date is shown.
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