Greenlee CM-450 User manual

INSTRUCTION MANUAL
MANUAL DE INSTRUCCIONES
MANUEL D’INSTRUCTIONS
Read and understand all of the instructions and
safety information in this manual before operating or
servicing this tool.
Lea y entienda todas las instrucciones y la
información sobre seguridad que aparecen en este
manual, antes de manejar estas herramientas o darles
mantenimiento.
Lire attentivement et bien comprendre toutes les
instructions et les informations sur la sécurité de ce
manuel avant d’utiliser ou de procéder à l’entretien de
cet outil.
CM-450
Digital
Clamp-on
Meter
Medidor digital
con pinza
Contrôleur
numérique
à pince
52033586 REV 1 © 2008 Greenlee Textron Inc. 3/08
CM-450
TRUE RMS

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Description
The Greenlee CM-450 Digital Clamp-on Meter is a hand-held testing device
capable of measuring up to 600 amps of alternating current, in addition to
measuring AC or DC voltage, frequency, and resistance. It also checks diodes and
verifies continuity. The CM-450 is a true RMS-reading meter.
Safety
Safety is essential in the use and maintenance of Greenlee tools and equipment.
This instruction manual and any markings on the tool provide information for
avoiding hazards and unsafe practices related to the use of this tool. Observe all
of the safety information provided.
Purpose of This Manual
This instruction manual is intended to familiarize all personnel with the safe
operation and maintenance procedures for the Greenlee CM-450 Digital Clamp-on
Meter.
Keep this manual available to all personnel.
Replacement manuals are available upon request at no charge at
www.greenlee.com.
Do not discard this product or throw away!
For recycling information, go to www.greenlee.com.
All specifications are nominal and may change as design improvements occur.
Greenlee Textron Inc. shall not be liable for damages resulting from misapplication or misuse
of its products.
® Registered: The color green for electrical test instruments is a registered trademark of
Greenlee Textron Inc.
KEEP THIS MANUAL
Lifetime Limited Warranty
Greenlee Textron Inc. warrants to the original purchaser of these goods for use
that these products will be free from defects in workmanship and material for
their useful life, excepting normal wear and abuse. This warranty is subject to
the same terms and conditions contained in Greenlee Textron Inc.’s standard
one-year limited warranty.
For all Test Instrument repairs, contact Customer Service at 800-435-0786
and request a Return Authorization.
For items not covered under warranty (such as items dropped, abused, etc.), a
repair cost quote is available upon request.
Note: Prior to returning any test instrument, please check replaceable
batteries or make sure the battery is at full charge.

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CM-450
SAFETY ALERT SYMBOL
This symbol is used to call your attention to hazards or unsafe practices
which could result in an injury or property damage. The signal word, defined
below, indicates the severity of the hazard. The message after the signal
word provides information for preventing or avoiding the hazard.
Immediate hazards which, if not avoided, WILL result in severe injury or
death.
Hazards which, if not avoided, COULD result in severe injury or death.
Hazards or unsafe practices which, if not avoided, MAY result in injury or
property damage.
Read and understand this material before operating or
servicing this equipment. Failure to understand how to
safely operate this tool could result in an accident causing
serious injury or death.
Electric shock hazard:
Contact with live circuits could result in severe injury or
death.
Important Safety Information

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Important Safety Information
Electric shock and fire hazard:
Do not expose this unit to rain or moisture.
Do not use the unit if it is wet or damaged.
Use test leads or accessories that are appropriate for the application. Refer
to the category and voltage rating of the test lead or accessory.
Inspect the test leads or accessory before use. They must be clean and dry,
and the insulation must be in good condition.
Use this unit for the manufacturer’s intended purpose only, as described in
this manual. Any other use can impair the protection provided by the unit.
Failure to observe these warnings could result in severe injury or death.
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Electric shock hazard:
Do not operate with the case open.
Before opening the case, remove the test leads (or jaw) from the circuit and
shut off the unit.
Failure to observe these warnings could result in severe injury or death.
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Electric shock hazard:
Using this unit near equipment that generates electromagnetic interference
can result in unstable or inaccurate readings.
Unless measuring voltage or current, shut off and lock out power. Make sure
that all capacitors are discharged. Voltage must not be present.
Failure to observe these warnings could result in severe injury or death.
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CM-450
Important Safety Information
Electric shock hazard:
Do not attempt to repair this unit. It contains no user-serviceable parts.
Do not expose the unit to extremes in temperature or high humidity. Refer to
“Specifications.”
Failure to observe these precautions may result in injury and can damage the
unit.
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Electric shock hazard:
Do not change the measurement function while the test leads are connected to
a component or circuit.
Failure to observe this precaution may result in injury and can damage the unit.
Statement of Conformity
Greenlee Textron Inc. is certified in accordance with ISO 9000 (2000) for our
Quality Management Systems.
The instrument enclosed has been checked and/or calibrated using equipment
that is traceable to the National Institute for Standards and Technology (NIST).

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Identification
1. Jaw
2. Position error marks
3. Jaw center marks
4. Lever
5. Hold button
6. Relative measurement button
7. Display
8. Select button
9. Frequency button
10. Selector switch
11. Negative, common (COM), or ground input
terminal
12. Volts or resistance (VΩ) input terminal
Display Icons
13. Auto ranging is enabled.
14. Diode test
15. Continuity mode
16. Hold function is enabled.
17. Low battery indicator
18. ∆ Relative measurement is enabled.
19. MMega (106)
20. ΩOhms
21. Hz Hertz
22. kkilo (103)
23. AAmps
24. VVolts
25. mmilli (10-3)
26. O.L. Overload indicator
27. –Negative polarity indicator
28. AC measurement is selected.
29. DC measurement is selected.
Symbols on the Unit
Warning—Read the instruction manual
Risk of electric shock
Double insulation
Recycle product in accordance with manufacturer’s directions
Note: Unidentified icons are
not used on this model.
12
9
6
5
3
2
11
10
8
7
1
4
19
18
21
20
23
29
28
27
13 1514 16 17
242526
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CM-450
Using the Features
Selector Switch
Slide switch to desired mode of operation:
AC voltage
DC voltage
AC current
ohms/continuity/diode
Return switch to OFF position when not in use.
Select Button (SELECT)
Momentarily press to select resistance, continuity, or diode test when the
Selector switch is set to .
Frequency Button (Hz)
Press to measure frequency.
Note: The sensitivity of the frequency measurement function varies with the
measurement range. To automatically select a sensitivity level, measure the
voltage level first, and then press Hz. Pressing Hz before making a measurement
may give higher sensitivity. Reading may be zero when sensitivity is too low.
Electrical noise may cause unstable readings.
Hold Button (HOLD )
Press momentarily to hold the present value on the display. will appear on
the display.
Press again to return to normal mode.
Relative Measurement Button (∆)
This feature finds the difference between two measurements.
While taking a measurement, press ∆to set the display to zero. ∆ will appear
on the display.
Take the second measurement. The value on the display will be the difference
between the two measurements.
Press again to exit this mode.
Auto Power Off
To extend battery life, the meter will shut itself off after approximately 30 minutes
of inactivity. To restore power, press any button.
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AC Measurement
AC measurements are usually displayed as RMS (root mean square) values. The
RMS value is equal to the value of a DC waveform, which would deliver the same
power if it replaced the time-varying waveform. Two AC measurement methods
are average-responding RMS calibrated and true RMS-reading.
The average-responding RMS calibrated method takes the average value of the
input signal after full wave rectification, multiplies it by 1.11, and displays the
result. This method is accurate if the input signal is a pure sine wave.
The true RMS-reading method uses internal circuitry to read the true RMS value.
This method is accurate, within the specified crest factor limitations, whether the
input signal is a pure sine wave, square wave, triangle wave, half wave, or signal
with harmonics. The ability to read true RMS provides much more measurement
versatility. The Greenlee CM-450 is a true RMS meter.
The Waveforms and Crest Factors table shows some typical AC signals and their
RMS values.
Waveforms and Crest Factors
Waveform
RMS Value 100 100 100 100
Average
Value 90 100 87 64
Crest Factor*
(x)1.414 1 1.73 2
* The crest factor is the ratio of the peak value to the RMS value; it is
represented by the Greek letter x.

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CM-450
Operation
Electric shock hazard:
Contact with live circuits could result in severe injury or
death.
1. Set the Selector switch according to the Settings Table. Momentarily press the
SELECT button to select mode.
2. Refer to “Typical Measurements” for specific measurement instructions.
3. Test the unit on a known functioning circuit or component.
If the unit does not function as expected on a known functioning circuit,
replace the battery.
If the unit still does not function as expected, call Greenlee for technical
assistance at 800-435-0786.
4. Take the reading from the circuit or component to be tested.
Settings Table
To measure
this value …
Set the Selector
switch to this
symbol …
This icon
will appear
on the
display …
Connect
red lead
to …
Connect
black
lead
to …
AC Current*
(600 A max.) and AN/A N/A
Frequency of a
current
(600 A max.)
and press Hz Hz N/A N/A
Voltage
(600 V max.)
and V
+ COM
and V
Frequency of a
voltage signal or
and press Hz Hz + COM
Resistance MΩ + COM
Continuity**
and press SELECT Ω+ COM
Diode
and press SELECT
2 times and V+ COM
* AC current measurements are made using the jaw.
** Tone indicates continuity. The threshold is between 5 Ω and 120 Ω.
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Typical Measurements
AC Amps
Clamp Around Wire
Notes:
Clamp the jaw around
one conductor only.
Close the jaw completely to
ensure accurate measurement.
Center the wire in the jaw for
highest accuracy.
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Clamp Around Line Splitter
Notes:
The Greenlee 93-30 Line Splitter is divided.
One section renders amps; the other
renders amps multiplied by 10.
Close the jaw completely to ensure accu-
rate measurement.
Center the line splitter in the jaw for
highest accuracy.
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