Casella CEL CEL-450 User Manual
CEL-450 & CEL-490
REAL-TIME
SOUND LEVEL METERS
Provisional Handbook
HB3307.01
April 2004
CASELLA CEL
Regent House, Wolseley Road
Kempston, Bedford
MK42 7JY, U.K.
Phone: +44 (0) 1234 844 100
Fax: +44 (0) 1234 841 490
E-mail: info@casellagroup.com
Web: www.casellagroup.com
CASELLA USA
17 Old Nashua Road #15
Amherst
NH 03031, U.S.A.
Toll Free: +1 800 366 2966
Fax: +1 603 672 8053
E-mail: info@casellausa.com
Web: www.casellausa.com
Contents
Page 2 - CEL-450/490 Operators Handbook
Contents
Warnings !
LOAD BATTERIES following the instructions given in
Section 1.3. Make sure they are inserted in the orientations
shown inside the battery compartment .
A single cell installed with the wrong polarity may still allow
the instrument to function, but will cause overheating
severe enough to rupture a cell, with consequent risk to the
operator and damage to the instrument.
DO NOT REMOVE the protective grid from Class 1
microphone capsules as this will expose the diaphragm,
which is extremely vulnerable to damage.
UNDER NO CIRCUMSTANCES should these instruments be
cleaned using a solvent based cleaner.
Repairs of damage caused by a failure to observe these
warnings will NOT be covered by the normal warranty
conditions.
Notes !
The CEL-450 and CEL-490 are supplied complete with Class 1 or Class 2
Electret Microphones and have no need of a 200 V polarizing supply.
Therefore no such supply is available and it is safe to ignore the 200 V
polarising supply warnings shown on CEL-250 or MK 250 microphone
packaging.
Throughout this book, display screens that are available only on a
CEL-490 will be shown with a dashed - - - - outline.
CEL-450/490 Operators Handbook - Page 3
Contents
Page 4 - CEL-450/490 Operators Handbook
Contents
Contents
Chapter . . . . . . . . . . . . . . . . . . . Page
1. INTRODUCTION . . . . . . . . . . . . . . . . . . 7
1.1 Display & Keys . . . . . . . . . . . . . . . . . . . . 7
1.2 Quick Edit . . . . . . . . . . . . . . . . . . . . . . . 9
1.3 Install Microphone, Preamplifier & Batteries . . . . 10
1.4 Switch Instrument ON/OFF . . . . . . . . . . . . . 10
1.5 Description . . . . . . . . . . . . . . . . . . . . . 12
1.6 CEL-450 Sound Level Meters . . . . . . . . . . . . 14
1.7 CEL-490 Sound Level Meter . . . . . . . . . . . . 15
1.8 Instrument Power Supplies . . . . . . . . . . . . . 16
1.9 dB23 SoundTrack Software . . . . . . . . . . . . . 17
2. PRELIMINARY OPERATIONS . . . . . . . . . . . . 19
2.1 Select Instrument Configuration (Language,
Microphone Response Etc.) . . . . . . . . . . . . . 19
3. SELECT MEASUREMENT MODE,
TIMER SETTINGS & SETUP . . . . . . . . . . . . 23
3.1 Select Measurement Mode
(Bandwidth) . . . . . . . . . . . . . . . . . . . . . 23
3.2 Select Run Timing . . . . . . . . . . . . . . . . . . 23
3.3 Select Measurement Setup
(Factory- or User-Prepared Setups) . . . . . . . . . 27
3.3.1 Select Broadband Measurement Setup . . . . . . . 27
3.3.2 Select Narrow Band Measurement Setup . . . . . 32
4. ACOUSTIC CALIBRTION CHECK . . . . . . . . . . 37
4.1 Perform Acoustic Calibration Check . . . . . . . . 37
4.1.1 Automatic Calibration Check . . . . . . . . . . . . 38
4.1.2 Manual Calibration Check . . . . . . . . . . . . . . 41
5. OPERATION . . . . . . . . . . . . . . . . . . . . 45
5.1 Measurement . . . . . . . . . . . . . . . . . . . . 45
5.1.1 Start Measurement . . . . . . . . . . . . . . . . . 45
5.1.2 Broadband Measurement . . . . . . . . . . . . . . 46
5.1.3 Narrow Band Measurement . . . . . . . . . . . . 49
5.2 Recall Stored Data . . . . . . . . . . . . . . . . . 54
CEL-450/490 Operators Handbook - Page 5
Contents
Chapter . . . . . . . . . . . . . . . . . . . Page
5.3 Delete Stored Data . . . . . . . . . . . . . . . . . 56
5.4. Format Memory . . . . . . . . . . . . . . . . . . . 57
5.5 Use With Tape and DAT Recorders
(Including Calibration For Line Input) . . . . . . . . 58
4.5.1 Recording . . . . . . . . . . . . . . . . . . . . . . 59
4.5.2 Replay . . . . . . . . . . . . . . . . . . . . . . . . 61
6. SPECIFICATION . . . . . . . . . . . . . . . . . . 63
6.1 General . . . . . . . . . . . . . . . . . . . . . . . 63
6.2 Measurement Functionality . . . . . . . . . . . . . 67
6.2.1 CEL-450 Versions . . . . . . . . . . . . . . . . . . 67
6.2.2 CEL-490 Versions . . . . . . . . . . . . . . . . . . 69
7. PARTS & WARRANTY . . . . . . . . . . . . . . 71
7.1 Schedule of Parts . . . . . . . . . . . . . . . . . . 71
7.2 Instrument Servicing & Warranty . . . . . . . . . . 72
Getting Started
The following steps will get your CEL-450 or CEL-490 started.
1. Refer to Sections 1.1 and 1.2 to learn what is shown on the
display and how to use the Quick Edit function.
2. Install the microphone, preamplifier and batteries according to
Section 1.3.
3. Switch the instrument ON and follow the preliminary messages
as described in Section 1.4.
The messages indicate the instrument type and version.
4. Check “Hints for using Menus” between Chapters 1 and 2.
5. Select the display language and microphone response according
to Section 2.1.
6. Select a bandwidth, run timing and pre-set measurement set-up
according to Chapter 3.
7. Perform an acoustic calibration check as detailed in Chapter 4.
8. Start measurement and data logging as described in Section 5.1.
9. Recall stored data it according to Section 5.2.
10. Record data on a tape or DAT recorder and replay it as described
in Section 5.5.
Page 6 - CEL-450/490 Operators Handbook
Introduction
1. INTRODUCTION
Please read Sections 1.1 to 1.4 before commencing measurement. For a
quick introduction to instrument operations, Chapter 4 may be used as a
tutorial.
1.1 Display & Keys
Figure 1: Display & Key Identities
(Further icons may be shown during operation)
CEL-450/490 Operators Handbook - Page 7
Introduction
The broadband screen in Figure 1 shows one principal and four
subordinate parameters, where the principal parameter is a level as
identified below.
The following frequency weightings may be shown:
A-, C- and Z- (Linear) weighted.
The following time weightings and other identities may be shown.
S Slow.
F Fast.
I Impulse.
pk Peak.
mx Maximum.
mn Minimum.
eq Equivalent continuous level.
AV Average level.
Tm3 Taktmaximal 3 sek.
Tm5 Taktmaximal 5 sek.
EP,v Leq based noise dose normalised to a user
specified period of hours and minutes.
When the period is specified as 8 hours, this
measurement unit will be shown as EP,d.
TWAv Time Weighted Average is the normalised time
averaged sound pressure level with the selected
frequency and time weighting that represents
the total average of a persons workplace noise
exposure averaged over a user specified period
of hours and minutes.
This unit of measurement is specified in the
USA: OSHA standard 1910-95 published in 1983.
When the period is specified as 8 hours, this
measurement unit will be shown as TWA.
N Percentile sound level.
AE Sound exposure level.
HML Calculated as L
Ceq
- L
Aeq
Page 8 - CEL-450/490 Operators Handbook
Introduction
Figure 2: Quick edit functions
1.2 Quick Edit
All control functions for the CEL-450 and CEL-490 are accessed via menu
displays. In addition a powerful Quick Edit facility can be invoked by
the key to allow measurement parameters and settings to be
changed quickly and easily on screen. Figure 2 shows how the quick edit
function enables the cursor keys to edit the current settings.
CEL-450/490 Operators Handbook - Page 9
Introduction
1.3 Install Microphone, Preamplifier
& Batteries
Screw the Class 1 microphone “finger tight” on to the preamplifier. With
the instrument switched OFF, insert the connector of the preamplifier
plus Class 1 microphone or Class 2 microphone / preamplifier unit into
the socket in the cone at the top of the instrument case. Face the red
dot on the preamplifier to the front of the instrument so that the key
engages in a keyway in the socket to ensure correct pin connection.
(To disconnect the
preamplifier unit from the
instrument, pull on the
knurled sleeve.)
Load four new 1.5 V
batteries (AA or equivalent)
into the battery compartment in the rear of the
instrument (Figure 3).
Make sure they are
inserted in the orientations
Figure 3: Battery orientation
One cell installed with wrong polarity may still
allow the instrument to function, but can
cause overheating severe enough to rupture a
cell and damage the instrument.
shown inside the
compartment.
1.4 Switch Instrument ON/OFF
1. Press to switch the instrument ON.
The instrument starts a series of self tests, during which it
indicates the instrument type, firmware version, preamplifier
type and interface status.
Page 10 - CEL-450/490 Operators Handbook
Introduction
Inst. Type 450/490
Inst. Version A = Broadband
B = Octave band
C = Third octaves
1 = Class 1
2 = Class 2
Firmware version
Program version and issue
Interface status
Inst. identification number
At the end of the self test sequence, the instrument displays
memory information and battery voltage,
Current date and time
followed by the identity of the last used setup.
Last used setup
Finally it enters calibration check mode (described in Chapter 2).
The dates and times of the last 4
calibrations are stored.
See Section 2.2.
CEL-450/490 Operators Handbook - Page 11
Introduction
2. Press to switch the instrument OFF when all measurement,
setup and data recall operations are finished.
1.5 Description
Both the CEL-450 and CEL-490 Sound Level Meters make use of recent
developments in digital processors to feature a full 0 - 140 dB dynamic
range on a single uninterrupted scale. In addition, the narrow band
versions of these instruments offer real time frequency analysis.
Versions of these instruments are available with Class 1 or
Class 2 measurement accuracy to give an ability to make comprehensive
sound level measurements.
The main
difference between the
CEL-450 and CEL-490 are
the additional timing
facilities included in the
CEL-490. The CEL-450 is
intended primarily to make
Cumulative Measurement x x
Profile Measurement x x
Period Measurement x
Duration Timers x x
Delay Timers x
Ln% Measurement x
the noise measurements required for Industrial Hygiene and Health &
Safety standards, while the more comprehensive timing features of the
CEL-490 make it more suited to the monitoring of Environmental noise.
Versions of both instruments are available for broadband
measurement, broadband plus octave band, and broadband, octave band
and third-octave band measurement. All frequency bands operate in real
time, using Class 0 filters.
To simplify
operation, frequently used
measurement setups can
be stored for re-use. The
setup memory can
accommodate one factory
setup and up to four user
specified setups for each
bandwidth.
Class 1 and Class 2 Measurement.
Broadband, Octave Band and Third Octave
Band versions.
Simultaneous measurement of up to 16
parameters in broadband mode.
Simultaneous measurement of up to 10
parameters in narrow band mode.
Quick Edit function for immediate parameter
change.
One factory setup and up to four user
specified setups stored for each bandwidth.
Up to four profiles can be attached to each
measurement.
CEL-450 CEL-490
Page 12 - CEL-450/490 Operators Handbook
Introduction
Figure 4: Simplified menu structure
(Some of these options may not be available on all versions)
Simple procedures allow a measurement setup to be selected
and the instrument to make the required measurements and save them
automatically in separate data memories for each bandwidth.
Data stored in the memory can be recalled to the display for
inspection, so that the operator can confirm that the results are valid
before leaving the test site.
The instruments can be operated and deliver adequate results
without the need for other equipment, beyond an acoustic calibrator. All
operations can be controlled via the instrument keypad and simple menu
options. Figure 4 shows the basic arrangement of the main menu, while
a more comprehensive menu structure is given on the fold out sheet at
the back of this book.
However, the instruments become even more versatile when
their measurement and setup data is downloaded to a PC using the
dB23 Windows™ based software. This software has the facilities
expected of fully featured Windows™ packages offering post
processing, cut and paste between applications, comprehensive word
processing capabilities, and extensive on screen graphing facilities.
CEL-450/490 Operators Handbook - Page 13
Introduction
These instruments are constructed to withstand some of the
toughest industrial conditions with cases formed from a polyester/
polycarbonate material, giving them a high resistance to damage. Data
integrity is further protected by the use of robust electret microphones.
1.6 CEL-450 Sound Level Meters
The CEL-450 is ideal for on-site noise surveys and can also monitor
personal noise exposure in accordance with European - ISO or USA OSHA and DOD standards. The following weightings can be set:
RMS: A, C, Z (see section 1.1) weightings,
Peak: A, C, Z weightings,
Time: F (fast), S (slow), I (impulse),
Q: 3, 4, 5, 6 energy conversion factor.
Broadband models can measure all of the following parameters simultaneouslywith a single time constant.
L
AF
L
AFmx
L
AFmn
L
Aeq
L
AIeq
L
Zpk
L
AE
L
Ep,v
L
Tm3
L
Tm5
TWA
v
Sound level, with current weightings (A and F
are shown),
Maximum level, with current weightings,
Minimum level, with current weightings,
Equivalent continuous level, with current
frequency weighting,
Together with L
is used for HML calculations
Ceq
of heaing damage,
Equivalent continuous level, with impulse
weighting,
Linear peak,
Sound exposure level (sometimes known as SEL),
Noise dose normalised to a user selected
(variable) period of hours and minutes,
When the period is set to 8 hours, this will be
shown as L
ex,8h
.
Cumulative average of fast weighted maximum
values taken over 3 s periods (Taktmaximal 3),
Cumulative average of fast weighted maximum
values taken over 5 s periods (Taktmaximal 5),
Time Weighted Average is the normalised time
averaged sound pressure level with the selected
frequency and time weighting that represents
Page 14 - CEL-450/490 Operators Handbook
Introduction
the total L
of a person’s workplace noise
Avg
exposure averaged over a user selected
(variable) period of hours and minutes.
This unit is specified in the USA: OSHA standard
1910-95 published in 1983. When the period is
set to 8 hours, the unit will be shown as TWA.
L
Avg
HML This value is the calculation: L
Average level over the measurement period.
- L
Aeq
.
Ceq
Profiles Up to 4 parameters can be selected to have their
profile stored. Period times between 10 ms and
30 minutes can be selected.
Narrow band models can measure and scan the following parameters
simultaneously.
L
AF
Sound level, with current weightings (A and F
are shown here),
L
AFmx
L
AFmn
L
Aeq
Maximum level, with current weightings,
Minimum level, with current weightings,
Equivalent continuous level, with current
frequency weighting.
L
pk
User selectable measured broadband L
or L
presented as a single result.
Apk
Zpk
, L
Cpk
Cumulative measurements are saved for each user enabled paramater.
In addition, broadband mode allows up to four profiles to be stored for
each result set, with intervals from 10 ms to 30 min. LN% statistical data
can be measured and stored.
All sound level measurement parameters can be set from the
keypad and the whole measurement range is shown on a single 0 - 140
dB scale. The instruments have 2 Mb of memory, which is used on a
first-come basis. Duration timers can also be set in the main menu,
allowing the instrument to automatically switch off after a pre-defined
time.
1.7 CEL-490 Sound Level Meters
The CEL-490 is recommended for detailed measurements as, in addition
to the CEL-450 capabilities described above, it has more comprehensive
CEL-450/490 Operators Handbook - Page 15
Introduction
run timing facilities. These allow it to operate with user set delayed start
and stop times, and to store period results taken at regular intervals.
1.8 Instrument Power Supplies
All of these instruments are powered by a set of four standard AA size
batteries in a compartment in the back of the instrument case, and it is
recommended that alkaline IEC Type LR6 be used. Rechargeable
batteries can also be employed, but some types may give a shorter
operating life. Zinc carbon batteries are NOT recommended.
If there is doubt whether the batteries will be able to power the
instrument for the start and stop times set, or when measurements are
needed over long periods, the instrument can be powered directly from
an external 12 V DC supply without the need to remove the internal
batteries.
DAMAGE to the instrument will occur if an
external power supply exceeds 14 V DC. The
nominal external supply is 12 V DC.
External power for the instrument is supplied via a 2.1 mm co-axial 2-line
D.C. connector in the bottom of the instrument case. Terminal polarity is
+12 V DC on the tip and 0 V DC ground on the sleeve.
A Casella CEL Universal Power Supply (-PC18) may be used to
power the instruments from nominal 110-240 V 50/60 Hz mains supplies.
To prevent loss of data should an external power supply be interrupted
for any reason during measurement, it is recommended that a usable set
of batteries be kept in the instrument.
In general, download all important data and remove the batteries
from the instruments when they are to be out of use for some time.
Note that when an instrument is returned to battery operation
after being powered from an external supply, either: switch the
instrument OFF then ON again, or: disconnect ALL devices from the DC
input socket, in order to avoid additional discharging of the internal
batteries.
The instrument contains a built in lithium battery to maintain
stored data and setups for periods while the instrument is switched OFF.
Page 16 - CEL-450/490 Operators Handbook
Introduction
1.9 dB23 SoundTrack Software
The CEL-6811 dB23 Software enables data collected by the CEL-450 and
CEL-490 to be downloaded to a PC for storage, manipulation and the
production of reports. It also enables the PC to exercise comprehensive
control over the sound level meter.
Data can be exported in ASCII format to proprietary word
processing software, while profile and statistical data can be exported as
tab-delimited text files suitable for use with spreadsheets such as Lotus
123™ (Release 2 or later) and MS Excel™. In addition, on-screen
graphing and reporting facilities are available and full on-line control can
be exercised over the sound level meter.
The dB23 Software runs under MS Windows® taking advantage
of the control facilities offered by the environment, so that once
installed, users with a modest knowledge of Windows will find many
operations are performed almost instinctively with a minimum of learning
time.
Downloading is performed under the control of the PC. Data
from each of the measurement runs in the sound level meter is
transferred as a series of associated datafiles together with a note file in
which comments and information can be written. Once downloaded, the
user can display the following information:
¤ Run summary for each run,
¤ Data file,
¤ Up to four profiles for each run,
¤ Notepad for user-entered notes.
CEL-450/490 Operators Handbook - Page 17
Introduction
1. and displayed on a menu
2. In general, and keys move the
3. In general, and keys change the
4. at the bottom of a menu list indicates
5. An indication such as 3/5 at the bottom of a
6. Settings left highlighted on a menu screen
Hints For Using Menus
show which option keys are active.
reverse video cursor from field to field.
entry in the cursor field.
there may be further options.
menu1 shows that option 3 has been
selected from the 5 available.
become the active options.
Note 1: The illustrations in this book are for full featured
Page 18 - CEL-450/490 Operators Handbook
instruments, other instruments may offer fewer or
no options.
Preliminary Operations
2. PRELIMINARY OPERATIONS
2.1 Select Instrument Configuration
(Language, Microphone Response Etc.)
Select the language in which the instrument will present menu options.
This should be the first operation so that the displays and options will be
understood.
Similarly, to get the most accurate results, these instruments
must be operated with a known microphone directional response and be
calibrated for this response.
When the language and microphone response are known to be
correct for the proposed measurement task, go directly to Section 2.2
Calibration Check.
European IEC standards require measurements to be performed
with microphones that have a Free Field response, while the U.S.A.
ANSI standards require Random Incidence microphones. The microphone response is set via the Configuration menu.
Normally, these more permanent characteristics must be set
only once, as the instrument will store the settings and use them the
next time it is switched on.
Proceed as follows.
Operation Press Display Shows Comments
1. Switch the
instrument
ON
Start up messages are
displayed that include:
Instrument Type,
Firmware Version, Etc.
Finally, the Configuration
screen is displayed with
Battery Voltage, followed by
the Calibration check screen.
2. Select the
Main menu
2 times
This is the Main menu.
It gives access to further
menus that select:
Measurement Mode,
Measurement Setup,
Calibration Sequence,
Timers
Data Recall from Memory,
Instrument Configuration,
Status.
CEL-450/490 Operators Handbook - Page 19
Preliminary Operations
Operation Press Display Shows Comments
3. Select the
Configure
option
or
Move the reverse video
cursor to the required line.
4. Move to
the
Configure
menu
5. Select the
Language
option
6. Move to
the
Language
menu
7. Select the
required
language
or
or
This menu allows the
following items to be set:
RS232 Communication Baud
rates from 1200 to 115200,
Menu Language,
Backlighting Durations of 1,
5, 10, 15, 30 s, OFF or
Manual press ON press OFF,
Graph span and offset,
Instrument Time & Date,
Microphone Response Free
Field or Random,
A.C. Output for line
transmission or recording.
Move the reverse video
cursor to the required line.
This menu allows the
following languages to be
selected for menu
presentation:
English,
Français,
Deutsch,
Italiano,
Español.
The highlighted language
will be used for menu
presentation.
This setting will also be
stored and used next time
the instrument is switched
on.
Press to return to the
Configuration menu.
Page 20 - CEL-450/490 Operators Handbook
Preliminary Operations
Operation Press Display Shows Comments
8. Select the required microphone response (and other
configuration items) in the same way.
Date and time are set using the quick edit function as
follows.
9. Select the date and time option by moving the reverse
video cursor to the required line on the Configure menu.
10. Move to
Date and
Time menu
The highlighted entries will
be used. These settings will
also be stored and used
next time the instrument is
switched on.
This menu allows the time
and date to be set.
11. When the
date and
time are to
be changed
12. Return to
the Main
menu 2 times
This enables the quick edit
function.
Use and to select a
field, and and to
change the entry.
The day will be determined
automatically from the date
and month entries.
Press again to save
the date and time.
All of the configuration settings that have been left highlighted on the
menu screens, plus any changes to the time and date, will be stored for
use next time the instrument is switched on.
CEL-450/490 Operators Handbook - Page 21
Preliminary Operations
Page 22 - CEL-450/490 Operators Handbook
Select Mode & Setup
3. SELECT MEASUREMENT MODE,
TIMER SETTINGS, & SETUP
3.1 Select Measurement Mode (Bandwidth)
The measurement mode specifies the bandwidth that is to be used for
measurement. Select the measurement mode as follows.
Operation Press Display Shows Comments
1. Start from
the
Main menu
This is the Main menu
screen.
2. Select the
Measure
Mode
option
3. Move to
the
Measure
Mode
menu
and
Move the reverse video
cursor to the required line.
This menu allows any of the
available bandwidths to be
selected.
The highlighted setting will
be used. This setting will
also be stored and used the
next time the instrument is
switched on.
When the required bandwidth has been selected, press once to
obtain a Measurement screen or twice to obtain the Main menu that
gives access to all settings and stored data.
3.2 Select Run Timing
Measurements can be timed as follows.
Timers Off Manually timed. This allows the user to start and
stop a measurement run whenever they want.
CEL-450/490 Operators Handbook - Page 23
Select Mode & Setup
Duration Run for a predetermined duration after pressing
the run key. This can be used to time a work
shift, or to measure some particularly noisy
operation with a known work cycle.
Sync timer (CEL-490 only) Run for a predetermined duration
that is synchronized to start at the same time as
the next measurement period which was set via
the Setup menu. For example, if the Period Time
is 30 minutes, the run will start when the time is
exactly on the hour or 30 minutes past the hour.
This method is suggested when precisely timed
measurements are required.
Delay Timer (CEL-490 only) Run with preset start and stop
times. This allows the instrument to start and
stop up to seven accurately timed measurement
runs while unattended.
In this way, different measuring times can be set
for each day of the week with the option of
repeating them over a period of several weeks.
Each time is set as Day:Hour:Minute, so that
delays can be set up to a month ahead.
Set the Day to 00, to use this as a 24 hour timer.
Once set, the timer settings become valid for all bandwidths and setups.
Display screens that are available only for a CEL-490 are shown with a
dashed - - - - line.
When timed measurements are required, proceed as follows.
Operation Press Display Shows Comments
1. Start from
the
Main menu
This is the Main menu
screen.
Page 24 - CEL-450/490 Operators Handbook
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