Casella CEL CEL-414 - Manual (Page 28)

If several measurements are being
made during the same period, it will
be most useful to reset all registers
simultaneously by means of a
general instrument reset.
However, the L eq register alone may
be reset by pressing the RESET
button while “LEQ” is being shown
on the display.
Refer to Sections 3.2 and 3.3 for
further information about resetting.
6.7Measurement of Sound
Exposure Level - SEL (not
CEL-266/3, CEL-328/3 or
CEL-414/3)
The sound exposure level is used in the
comparison of energy levels in separate
noise events that may have different dura-
tions.
On the CEL-493/3 only, the timing of
events may be determined in either of
two ways. An event can start when a
user set threshold level is crossed for
longer than a user set onset time (delay)
and finish after the threshold is re-
crossed. Alternatively, the timing of
events may be determined manually, us-
ing the RESET and PAUSE controls, as
for the remaing instruments.
6.7.1Event Times Deter-
mined by Threshold Level
(only CEL-493/3)
An event will start and calculation com-
mence as soon as the preset threshold
level is exceeded for more than the pre-
determined delay time, and finish 5 sec-
onds after the threshold is re-crossed.
These relationships are illustrated in Fig-
ure 9.
When the CEL-493/3 is first switched
ON, the threshold level defaults to full
scale deflection, so that if SEL mode is
selected, no measurements will be made.
With the instrument in any measurement
mode, set the threshold level and start
delay time as follows.
Delay Time Set
Event Duration
< 5s 5s
Time
890013
Sound Level
Threshold Level Set
Figure 9: Definition of an SEL event on the CEL-493/3
Page 24 - General CEL Sound Level Meters Handbook