BERTHOLD TECHNOLOGIES Uni-Probe LB 490 - Page 645

Uni-Probe LB 490
BERTHOLD TECHNOLOGIES GmbH & Co. KG
6 – 645
Volume 6 6 Explanations
6
6.5.2 Interference Radiation Detection Flow Chart
If radiation interference is detected, following will happen:
The measurement switches to the HALT mode.
• Measured value and current output are “held”.
• Error relay indicates alarm.
The measurement is “held” up to the end of the defined waiting
time.
At the end of the waiting time the system checks if the arriving
count rate is smaller than 1.5-times the calibrated empty count
rate (Io) (see scenario A). If not, the waiting time starts again.
If the count rate is below 1.5-times the empty count rate, the mea-
surement automatically switches to the RUN mode. Sigma detec-
tion (see scenario B) is disabled for 3 x measuring time (= dead
time).
Example:
If the measurement time is 20s, the dead time is 60s. This time is
needed for the measurement to adjust to a possibly changed level,
without triggering interference radiation detection. During this
time, interference radiation is detected only when the count rate
has increased to 1.5-times the empty count rate.
At the end of the waiting time the system checks if the arriving
count rate is smaller than 1.5-times the calibrated empty count
rate (Io).
Interference radiation
detected
Waiting time
Count rate
below
1.5 x Io?
Measurement in
RUN mode
without Sigma check
dead time =
3 x measuring time
Measurement in
RUN mode
with Sigma check
NO
YES