Extech Instruments AM300 User manual

User's Guide
Extech AM300
300A AC Analog Clamp Meter

AM300 V1.1 6/072
Introduction
Congratulations on your purchase of the Extech AM300 Analog Clamp Meter. This device
measure AC Voltage and Current, DC Voltage, and Resistance. This meter is shipped fully
tested and calibrated and, with proper use, will provide years of reliable service.
Safety
International Safety Symbols
This symbol, adjacent to another symbol or terminal, indicates the user must refer
to the manual for further information.
This symbol, adjacent to a terminal, indicates that, under normal use, hazardous
voltages may be present
Double insulation
SAFETY NOTES
•Do not exceed the maximum allowable input range of any function.
Function Maximum Input
A AC 300A AC
V DC, V AC 600V DC/AC
•Do not apply voltage to meter when resistance function is selected.
•Remove the battery if meter is to be stored for longer than 60 days.
WARNINGS
•Set function switch to the appropriate position before measuring.
•When measuring volts do not switch to current/resistance modes.
•Do not measure current on a circuit whose voltage exceeds 600V.
•When changing ranges always disconnect the test leads from the circuit under test.
CAUTIONS
•Improper use of this meter can cause damage, shock, injury or death. Read and
understand this user manual before operating the meter.
•Always remove the test leads before replacing the battery or fuses.
•Inspect the condition of the test leads and the meter itself for any damage before
operating the meter. Repair or replace any damage before use.
•Use great care when making measurements if the voltages are greater than 25VAC
rms or 35VDC. These voltages are considered a shock hazard.
•Always discharge capacitors and remove power from the device under test before
performing Resistance tests.
•Voltage checks on electrical outlets can be difficult and misleading because of the
uncertainty of connection to the recessed electrical contacts. Other means should be
used to ensure that the terminals are not "live".
•If the equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired.

AM300 V1.1 6/073
STANDARDS
PER IEC1010 OVERVOLTAGE INSTALLATION CATEGORY
OVERVOLTAGE CATEGORY I
Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in
which measures are taken to limit the transient overvoltages to an appropriate low level.
Note – Examples include protected electronic circuits.
OVERVOLTAGE CATEGORY II
Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be
supplied from the fixed installation.
Note – Examples include household, office, and laboratory appliances.
OVERVOLTAGE CATEGORY III
Equipment of OVERVOLTAGE CATEGORY III is equipment in fixed installations.
Note – Examples include switches in the fixed installation and some equipment for industrial
use with permanent connection to the fixed installation.
OVERVOLTAGE CATEGORY IV
Equipment of OVERVOLTAGE CATEGORY IV is for use at the origin of the installation.
Note – Examples include electricity meters and primary over-current protection equipment

AM300 V1.1 6/074
Description
Meter Description
1. Current clamp
2. Clamp opening trigger
3. Function Selector Switch
4. Scale Display
5. POINTER LOCK switch
6. Meter zero adjust
7. Zero ohms adjust
8. COM negative input jack for black test lead
9. OHMS positive input jack for red lead
10. VOLT positive input jack for red lead
Specifications
Function Ranges Accuracy
AC Current
(50/60Hz) 6, 15, 60, 150, and 300A AC ± 3% of Full Scale for 50/60Hz
AC Voltage
(50/60Hz) 300 and 600V AC ± 3% of Full Scale
DC Voltage 75V DC ± 3% of Full Scale
Resistance 2000Ω (20Ωmid-scale) ± 3% of Scale Length
Clamp jaw opening 1.5" (38mm) max.
Display Analog with Zero Adjustment
Input Impedance 240kΩ(75VDC range), 530kΩ(300VAC range, 1MΩ
(600VAC range),
AC bandwidth 50 to 60Hz (50 to 400Hz for 15 through 300ACA ranges)
Ambient conditions Temperature 32 - 104oF (0 - 40oC); Relative Humidity <80%
Operating Altitude 7000ft. (2000m) maximum.
Battery One (1) 1.5V ‘AA’ Battery
Fuse 0.5A / 250V glass fuse (6mm x 30mm); spare fuse supplied
Dimensions & Weight 9.0 x 2.8 x 1.5" (230 x 72 x 37mm); 14.7oz. (416g)
Safety For indoor use and in accordance with the requirements for
double insulation to IEC1010-1 (2001): EN61010-1 (2001)
Overvoltage Category II 600V, Pollution Degree 2.
1
2
5
6
7
10
3
4
9
8

AM300 V1.1 6/075
Operation
NOTES:Read and understand all Warning and Caution statements in this operation manual prior to using
this meter.
AC Current Measurements
WARNING: Ensure that the test leads are disconnected from the meter before making current clamp
measurements.
1. Set the scale to the highest range using the function thumbwheel switch. Step
down to the lower ranges as necessary in order to keep the reading in the upper
half of the scale.
2. Ensure that the Pointer Lock switch is set to the right-most position so that the
pointer may freely move.
3. Turn the Zero Adjust screw to zero
the meter display.
4. Press the trigger to open jaw. Fully
enclose only one conductor. For
optimum results, center the
conductor in the jaw.
5. The analog display pointer will
indicate the current reading.
AC/DC Voltage Measurements
1. Insert the black test lead into the negative COM terminal and
the red test lead into the positive Vterminal.
2. Set the display to the highest AC or DC Voltage range using
the thumbwheel switch. Step down to the lower ranges as
necessary in order to keep the reading in the upper half of
the scale.
3. Ensure that the Pointer Lock switch is set to the right-most
position so that the pointer may freely move.
4. Turn the Zero Adjust screw to zero the meter display.
5. Connect the test leads in parallel to the circuit under test.
6. The analog display pointer will indicate the voltage reading.
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AM300 V1.1 6/076
Resistance Measurements
WARNING: To avoid damage to the meter, do not apply voltage to the meter when
measuring resistance. Ensure that the circuit, device, or component under test is
disconnected from power before measuring resistance.
1. Insert the black test lead into the negative COM terminal and the
red test lead into the OHMS positive terminal.
2. Set the display scale to the OHMS position using the thumbwheel
switch.
3. Ensure that the Pointer Lock switch is set to the right-most
position so that the pointer may freely move.
4. With the test leads open, adjust the meter zero so that the pointer
is over the ∞symbol.
5. Touch the test lead tips together and adjust the 0 Ohms adjust
until the pointer is over the 0 ohms position.
6. Touch the test probe tips across the circuit or component under
test.
7. The analog display pointer will indicate the resistance reading.
Pointer Lock Function
The Pointer Lock switch freezes the pointer’s position and can be used as a ‘data hold’
feature. This feature is useful in dimly lit or hard to reach locations.
Maintenance
WARNING: To avoid electrical shock, disconnect the meter from any circuit and remove the test leads from
the input terminals before opening the case. Do not operate the meter with an open case.
Cleaning and Storage
Periodically wipe the case with a damp cloth and mild detergent; do not use abrasives or
solvents. If the meter is not to be used for 60 days or more, remove the battery and store it
separately.
Battery and Fuse Replacement
1. Remove the two (2) Phillips head screws at the rear of the meter.
2. Carefully open the meter housing.
3. Replace the 1.5V ‘AA’ battery if necessary
4. Replace the fuse if necessary with a 0.5A / 250V glass fuse (6mm x 30mm) or
equivalent. Note that a spare fuse is provided inside the meter housing.
5. Close the meter and replace the meter screws securely.
W

AM300 V1.1 6/077
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Support line [phone]
Technical Support: Extension 200; E-mail: [e-mail]
Repair & Returns: Extension 210; E-mail: [e-mail]
Product specifications subject to change without notice
For the latest version of this User Guide, Software updates, and other
up-to-the-minute product information, visit our website: www.extech.com
Extech Instruments Corporation, 285 Bear Hill Road, Waltham, MA 02451
Warranty
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a six month limited warranty
applies to sensors and cables). If it should become necessary to return the instrument for
service during or beyond the warranty period, contact the Customer Service Department at
[phone] ext. 210 for authorization or visit our website www.extech.com for contact
information. A Return Authorization (RA) number must be issued before any product is
returned to Extech. The sender is responsible for shipping charges, freight, insurance and
proper packaging to prevent damage in transit. This warranty does not apply to defects
resulting from action of the user such as misuse, improper wiring, operation outside of
specification, improper maintenance or repair, or unauthorized modification. Extech
specifically disclaims any implied warranties or merchantability or fitness for a specific
purpose and will not be liable for any direct, indirect, incidental or consequential damages.
Extech's total liability is limited to repair or replacement of the product. The warranty set
forth above is inclusive and no other warranty, whether written or oral, is expressed or
implied.
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also
provides NIST certification for most products. Call the Customer Care Department for
information on calibration services available for this product. Extech recommends that
annual calibrations be performed to verify meter performance and accuracy.
Copyright ©2007 Extech Instruments Corporation
All rights reserved including the right of reproduction in whole or in part in any form.