Greenlee CM-1200 User manual

999 3268.7 © 1999 Greenlee Textron IM 1412 7/99
CM-1200
CLAMP-ON AMMETER
AMPERÍMETRO
CON PINZA
PINCE
AMPEREMETRIQUE
DCA ZERO
PEAK HOLD
AUTO POWER OFF
V
V
A
OFF
Hz
K
A
AC /DC 1000A
TRUE RMS
CLAMP
MULTIMETER
A
A
Ω
V
V
Hz
0.1A
0.1A
1Ω
0.1V
0.1V
20Hz
— 1000A
— 1000A
— 40kΩ
— 1000V
— 600V
— 10kHz
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.

2
Description
The Greenlee CM-1200 Clamp-on Ammeter is a true RMS-reading meter intended to measure
AC/DC current, resistance, AC/DC voltage, frequency and to verify continuity. The large,
easy-to-read 3-3/4-digit LCD display has a maximum reading of 3999.
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
This instruction manual is intended to familiarize all personnel with the safe operation and
maintenance procedures for the Greenlee CM-1200 Clamp-on Ammeter.
Keep this manual available to all personnel.
Replacement manuals are available upon request at no charge.
and are registered trademarks of Greenlee Textron.
KEEP THIS MANUAL

CM-1200
3
Important Safety Information
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.
SAFETY ALERT SYMBOL
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 can result in an accident causing serious injury or death.

4
Important Safety Information
Electric shock hazard:
Contact with live circuits can result in severe injury or death.
Electric shock hazard:
• Do not use the unit if it is wet or damaged.
• Use test leads or accessories that are appropriate for the application. See the
category and voltage rating of the test lead or accessory.
• Inspect the test leads or accessory before use. The item(s) must be clean and dry,
and the insulation must be in good condition.
Failure to observe these warnings can result in severe injury or death.
Electric shock hazard:
• Do not apply more than the rated voltage between any two input terminals, or
between any input terminal and earth ground.
• Do not contact the test lead tips or any uninsulated portion of the accessory.
Failure to observe these warnings can result in severe injury or death.
• 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 can result in severe injury or death.

CM-1200
5
Do not change the measurement function while the test leads are connected to a
component or circuit.
Failure to observe this precaution can result in injury and can damage the instrument.
• Do not attempt to repair this unit. It contains no user-serviceable parts.
• Do not expose unit to extremes in temperature or high humidity. See Specifications.
Failure to observe these precautions can result in injury and can damage the instrument.
Unless measuring voltage, current or frequency, shut off and lock out power. Make
sure that all capacitors are discharged. Voltage must not be present.
Using this unit near equipment that generates electromagnetic interference can result
in unstable or inaccurate readings.

6
Identification
1. V Terminal
2. COM Terminal
3. Display
4. Lever
5. Jaw
6. Selector
7. Peak Hold Button
8. DCA Zero Button
9. Polarity Indication
DCA ZERO
PEAK HOLD
AUTO POWER OFF
V
V
A
OFF
Hz
K
A
AC /DC 1000A
TRUE RMS
CLAMP
MULTIMETER
A
A
Ω
V
V
Hz
0.1A
0.1A
1Ω
0.1V
0.1V
20Hz
— 1000A
— 1000A
— 40kΩ
— 1000V
— 600V
— 10kHz
3
21
4
9
5
6
7
8

CM-1200
7
Display Icons
10.
-
+
Low Battery
11. ΩOhms
12. kHz Kilohertz
13. Continuity
14. OL or -OL Overload
15. DC DC measurement is selected
16. AC AC measurement is selected
17. Peak Hold is enabled
18. True RMS reading is enabled
Symbols on the Unit
Read the instruction manual
Double Insulation
Battery
Risk of electric shock
kHz
16
15
10
17 12
14
11 13 18
Ω

8
AC Measurement
AC measurements are usually displayed as RMS ( root mean squared ) values. Two methods of
AC measurement are average-responding RMS calibrated and true RMS-reading.
The average-responding RMS calibrated method takes the average value of the input signal,
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, a square wave, sawtooth wave, half wave or signal with harmonics. The ability to read
true RMS provides much more measurement versatility. The CM-1200 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
Average Value
Crest Factor*
(ξ)
100 100 100 100
90 100 87 64
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 ξ.

CM-1200
9
Operation
1. Set the selector according to the settings table.
Settings Table
Electric shock hazard:
Contact with live circuits can result in severe injury or death.
* Tone indicates a circuit resistance is less than 100Ω.
** Frequency can also be measured with the jaw.
2. See Typical Measurements for illustrations of typical uses.
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, send the unit to Greenlee for repair.
To measure set the connect the and the
this value … selector to red lead black lead
this symbol … to … to …
Continuity* KΩVΩCOM
Current (AC) A .N/A N/A
Current (DC) A N/A N/A
Frequency** Hz VΩCOM
Resistance KΩVΩCOM
Voltage (AC) V VΩCOM
Voltage (DC) V VΩCOM

10
4. Take the reading from the circuit to be tested.
• If it is a DC reading, remove the clamp from the circuit and press the DCA Zero button.
Clamp the jaw around the circuit again to measure the actual DC current.
• For the peak value:
Note: Position the jaws to obtain a positive reading on DC current before using
Peak Hold, otherwise a reading of Ø will result.
Note: If is pressed while taking a measurent, an incorrect reading may result.
a) Remove unit from circuit.
b) Press Peak Hold button until icon disappears.
c) Press DCA Zero (for a DC reading only).
d) Press Peak Hold. Wait for icon to appear.
Note: Display will show 0.00.
e) Connect unit to circuit.
f) Read peak measured reading.