Extech Instruments 380947 User manual

User Guide
True RMS AC/DC Mini Clamp Meter
Model 380947

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Introduction
Congratulations on your purchase of the Extech 380947 True RMS Clamp Meter. This Clamp
meter measures current up to 400A DC/AC and measures Frequency up to 100 kHz. Careful use
of this meter will provide years of reliable service.
Safety
1. NEVER exceed the specified voltage/current maximum
2. USE EXTREME CAUTION when working with high voltages.
3. NEVER operate the meter unless the back cover and the battery/fuse door are in place and
fastened securely.
International Safety Symbols
Meter Description
1. Conductor under test
2. Clamp Jaws
3. Jaw trigger – Opens the meter jaws
4. ZERO / Relative button – Zeroes the DCA reading
5. Function select switch
6. HOLD button to freeze displayed reading
7. MAX/MIN button – Press to track and view highest and lowest readings
8. LCD Display with function indicators, units of measure, and bargraph

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Display icons
Low battery
DC Direct current
AC Alternating current
Minus sign
AUTO Automatic range (frequency only)
APO Auto power off
ZERO Zero function
HOLD HOLD function
MAX Highest reading
MIN Lowest reading
ACurrent unit of measure
MPrefix MEGA (millions of units)
kPrefix KILO (thousands of units)
Hz Hertz (unit of measure for frequency)
OL Over-range (for readings above 4032)
Bargraph display
The 40 segment bargraph display shown below is a graphical interpretation of the measurement. It
is displayed under the display digits on the LCD.
The bars in the bargraph indicate a presence of an electronic signal. The more bars showing, the
higher the signal. The digits below the graph help the user see how many bars are showing. If 40
segments are showing, the bars will reach the ‘40’ mark, if 20 bars are showing the bars will reach
the ‘20’ mark.
The bargraph is to be interpreted based on the range the meter is in while the measurement is
being made. If the bargraph shows 40 segments lit, then the signal is at the highest end of the
meter’s present range.

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Operation
AC Current Measurements
WARNING: To avoid electric shock, disconnect the test leads from the meter before making current
measurements.
1. Set the Function switch to the 4, 40, 100, or 400A AC range.
2. Press the Trigger to open the clamp jaw.
3. Clamp onto a single conductor (fully enclosing it). Do not allow a gap between the two halves of
the jaw.
4. Read the ACA value on the LCD.
DC Current Measurements
WARNING: To avoid electric shock, disconnect the test leads from the meter before making current
measurements.
1. Set the Function switch to the 40 or 400A DC range.
2. Press the DCA zero key to null the meter display.
3. Press the Trigger to open the current sense Jaw.
4. Fully enclose a single conductor to be measured. Do not allow a gap between the two halves of
the jaw.
5. Read the DCA value on the LCD.
Frequency Measurements
1. Ensure that at least 0.1A AC is detectable before measuring Frequency.
2. Set the Function switch to the Hz position.
3. Press the Trigger to open the jaw and fully enclose one conductor.
4. Read the Frequency measurement on the LCD in Hz.
MIN, MAX Function
Pressing the MIN/MAX key allows the meter to display ONLY the highest and the lowest readings
encountered. Press the MIN/MAX key once to view the minimum reading, press it again to view
the maximum reading. The LCD will toggle between the MIN and MAX values. Press and hold
MIN/MAX button for more than 2 seconds to return to normal operating mode. Zero function will
be disabled when MIN/MAX is enabled. MIN/MAX is not available in Hz mode.
Data Hold
To freeze the displayed reading on the LCD, press the Data Hold key (the HOLD icon will appear on
the display). To release the Data Hold function and return the meter to normal operation, press the
Data Hold key again (the HOLD icon will switch off).

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Zero button for Relative Measurements
1) Press the Zero key and the present measurement will Zero.
2) All subsequent measurements are displayed with respect to the zeroed reading. For example,
if a 20A reading is zeroed and a 30A reading is subsequently measured, the LCD will display
10A.
3) To return to normal operation, press the zero key one more time.
4) Note that Relative mode is not available if the MIN/MAX mode is enabled.
5) Relative mode is not available in Hz mode.
6) Note that the Zero button is disabled if Hz function is selected.
7) LCD displays relative numerical value without bargraph.
Battery Replacement
1. When the low battery symbol appears on the LCD, the batteries must be replaced.
2. Turn the meter off and remove the rear battery compartment screw.
3. Lift off the battery compartment cover and replace the two 1.5V AA cells.
4. Replace the compartment cover and secure the screw.
You, as the end user, are legally bound (EU Battery ordinance) to return all used
batteries, disposal in the household garbage is prohibited! You can hand over your
used batteries / accumulators at collection points in your community or wherever batteries
/ accumulators are sold!
Disposal: Follow the valid legal stipulations in respect of the disposal of the device at the
end of its lifecycle
Cleaning - Use only a dry cloth to clean the plastic case.
Specifications
General Specifications
Display 3-3/4 Digit LCD with 40 segment bargraph
Functions Current (ACA, DCA) and Frequency (Hz)
Polarity “-“ indicates negative polarity (positive polarity assumed)
Current sensor Hall effect
Overload OL
DCA zero adjust One-touch zero key (also used as a Relative function)
Display rate 3 readings/second (30 readings/second for bargraph)
Battery Two 1.5V AA batteries
Operating temperature -100C to 500C (40F to 1220F)
Operating Humidity < 85% RH
Power consumption 20mA DC approx.
Weight 190g (6.2 oz.) including battery
Dimensions 183 x 63.6 x 35.6mm (7.2 x 2.5 x 1.4”) (H x W x D)
Jaw opening 23mm (0.9”)
Standards IEC 1010 Category III 300V, Category II 600V

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Range Specifications
DC Current Resolution Accuracy (of rdg + digits) Overload Protect
40A 10mA ±(1.0% + 2d) 400A DC
400A (0 to 150A) 100mA ±(1.0% + 2d) 400A DC
400A (150 to 200A) 100mA ±(2.2% + 2d) 400A DC
400A (200 to 400A) 100mA ±(4.0% + 2d) 400A DC
AC Current Resolution 50/60Hz 40Hz - 1kHz Overload Protect
4A (0 to 500mA) 1mA ±(1.5% + 7d) ±(2.0% + 7d) 400A AC
4A (500mA to 4A) 1mA ±(1.5% + 3d) ±(2.0% + 4d) 400A AC
40A 10mA ±(1.5% + 3d) ±(2.0% + 4d) 400A AC
100A (0 to 100A) 100mA ±(1.5% + 3d) ±(2.0% + 4d) 500A AC
400A (100 to 200A) 100mA ±(2.2% + 3d) ±(2.5% + 4d) 500A AC
400A (200 to 400A) 100mA ±(4.0% + 3d) ±(5.0% + 4d) 500A AC
Frequency (Hz) Resolution Accuracy Sensitivity Overload Protect
40Hz to 250Hz 0.01 to 0.1Hz ±(0.5% + 2d) 3.0A 500A AC
250Hz to 10kHz 0.1 to 1Hz ±(0.5% + 2d) 0.3A 500A AC
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