Extech Instruments 380940 User manual

User's Guide

True RMS AC / DC Power Clamp Meter

Model 380940

380940-EU-EN-V4.1-4/12

Introduction

Congratulations on your purchase of the Extech 380940 True RMS Watt Clamp DMM. This meter

combines multimeter and clamp meter functionality in one convenient meter. 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. DO NOT measure voltage if the voltage on the "COM" input jack exceeds 500V above earth

ground.

4. NEVER connect the meter leads across a voltage source while the function switch is in the

current mode. Doing so can damage the meter.

5. ALWAYS discharge filter capacitors in power supplies and disconnect the power when

measuring.

6. ALWAYS turn off the power and disconnect the test leads before opening the back to replace

the fuse or batteries.

7. NEVER operate the meter unless the back cover and the battery/fuse door are in place and

fastened securely.

International Safety Symbols

380940-EU-EN-V4.1-4/12

Meter Description

1. Conductor under test

2. Clamp Jaws

3. Jaw trigger – Opens the meter jaws

4. ZERO button – Zeroes the DCA reading

5. Positive input jack (for red test lead)

6. Function select dial

7. HOD button freezes the displayed reading

8. MAX/MIN button – Press to track and view highest and lowest readings

9. LCD Display with function indicators and bargraph

10. COM input jack (for black test lead)

Function Select Switch

380940-EU-EN-V4.1-4/12

Display icons

Low battery

DC Direct current

AC Alternating current

Minus sign

AUTO Automatic range (frequency only)

MAN Manual range

ZERO Zero / Relative function

HOLD HOLD function

MAX Highest reading

MIN Lowest reading

Audible continuity

VVoltage unit of measure

ACurrent unit of measure

MPrefix MEGA (millions of units)

kPrefix KILO (thousands of units)

Ohm (unit of measure for resistance and continuity

Hz Hertz (unit of measure for frequency)

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.

380940-EU-EN-V4.1-4/12

Operation

AC + DC Power Watt Measurements

1. Connect the test leads to the voltage source in parallel with the load (refer to diagram).

2. Clamp onto one of the wires connected to the load.

3. Select the AC or DC voltage range using the function select switch and check the voltage

reading.

4. Select the AC or DC current range using the function select switch and check the current

reading.

5. Select the appropriate Watt range using the function select switch.

6. Read the KW value on the LCD.

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 AC Current position.

2. Press the jaw trigger and clamp around a single conductor fully enclosing it. Do not allow a gap

between the two halves of the jaw.

3. 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 DC Current position.

2. Press the DCA zero key to null the meter display.

3. Press the jaw trigger and clamp around a single conductor fully enclosing it. Do not allow a gap

between the two halves of the jaw.

4. Read the DCA value on the LCD.

380940-EU-EN-V4.1-4/12

AC Voltage Measurements

WARNING: To avoid electric shock or damage to the meter, do not make any voltage

measurements that exceed the maximum specified.

1. Set the Function switch to the AC Voltage position.

2. Insert the test leads to the meter as follows: Red lead to “V,,Hz” terminal; Black lead to the

COM input.

3. Measure voltage with the pointed end of the test leads. Remember that voltage measurements

are made in parallel with the device/circuit under test.

4. Read the ACV value on the LCD.

DC Voltage Measurements

WARNING: To avoid electric shock or damage to the meter, do not make any voltage

measurements that exceed the maximum specified.

1. Set the Function switch to the DC Voltage position.

2. Insert the test leads to the meter as follows: Red lead to “V,,Hz,” terminal; Black lead to the

COM input.

3. With the pointed end of the test leads measure voltage. Remember that voltage measurements

are made in parallel with the device or circuit under test.

4. Read the DCV value on the LCD.

Frequency Measurements

1. Set the Function switch to the Hz position.

2. Insert the test leads into the meter’s input terminals.

3. Connect the other ends of the test leads in parallel with the device/circuit under test.

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. Note that the meter will only change its displayed reading when a measurement

is taken higher than the previous MAX or lower than the previous MIN readings. The HOLD display

icon (along with the MIN or MAX icon) will appear on the LCD in MIN/MAX mode. Pressing the

MIN/MAX key a 3rd time returns the meter to normal operation.

Data Hold

To freeze the current reading on the LCD, press the Data Hold key. To release the Data Hold

function and return the meter to normal operation, press the Data Hold key again.

Relative Mode

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 and hold the zero key for 2 seconds.

4. Note that Relative mode is not available if MIN/MAX mode is enabled.

380940-EU-EN-V4.1-4/12

Auto Power OFF

To extend battery life, the meter will auto power off after 30 minutes of operation. To resume

operation either turn the meter OFF and then ON again or press the HOLD button.

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 (Battery ordinance) to return all used batteries

and accumulators; 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 (4000 count) LCD with 40 segment bargraph

Functions Watts, ACA, DCA, ACV, DCV, Frequency

Polarity “-“ indicates negative polarity; positive assumed

Current sensor Hall effect sensor type

Overload indication Left blinking digit

DCA zero adjust One touch zero key

Display rate 2 readings/second (20 readings/second for bargraph)

Auto Power Off Meter turns off automatically after 30 minutes

Battery Two 1.5V AA batteries

Operating temp. -100C to 500C (40F to 1220F)

Operating Humidity < 85% RH

Power consumption Approximately 10mA DC

Weight 190g (6.7 oz) including battery

Dimensions 183 x 63.6 x 35.6mm (7.2 x 2.5 x 1.4”) (HWD)

Jaw opening 23mm (0.9”) maximum conductor size

Standards IEC 1010 Category III 300V, Category II 600V

380940-EU-EN-V4.1-4/12

Range Specifications

Function Range Resolution Accuracy Overload protect

40kW 10W ±(1.5% + 3dgts) 250V, 400A

Note: 50/60Hz, PF 0.6 to 1, Vpeak < 360V

240kW 100W ±(1.5% + 3dgts) 600V, 400A

Note: 50/60Hz, PF 0.6 to 1, Vpeak < 850V

40kW 10W ±(2.5% + 3dgts) 250V, 400A

Note: 40Hz to 100Hz, PF 0.6 to 1, Vpeak < 360V

240kW 100W ±(2.5% + 3dgts) 600V, 400A

AC Power

Note: 40Hz to 100Hz, PF 0.6 to 1, Vpeak < 850V

40kW 10W ±(1.5% + 3dgts) 250V, 400ADC Power

240kW 100W ±(1.5% + 3dgts) 250V, 400A

DC Current 400A 100mA ±(1.5% + 3dgts) 600A DC

50/60Hz 40 to 100HzAC Current

True RMS, Crest factor

< 4 400A 100mA ±1.5% ±3dgts ±2.5% ±4dgts 600A AC

DC Voltage 400V 0.1V ±(1.0% + 2dgts) 800V DC

50/60Hz 40 to 1kHzAC Voltage

True RMS, Crest factor

< 4, Input impedance

10M

600V 1V ±(1.5% + 2dgts) ±(2.0% + 4d) 800V AC

Frequency 10Hz - 10kHz 0.01- 10Hz ±(0.8% + 2dgts) Sensitivity 10V 600V AC

www.extech.com

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