Extech Instruments Extech 380976 User manual

User Guide
1Φ/3Φ1000 Amp True RMS Power Clamp-On
Model 380976

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Introduction
Congratulations on your purchase of the Extech 380976 Power Clamp-On Meter. This device
measures 1Φ/3ΦPower (True, Apparent, and Reactive), Horsepower, Phase Angle, True RMS
Current/Voltage, Resistance, Capacitance, Frequency, & Temperature. Power measurements can
be achieved on 3- or 4-wire configurations. Please read the entire manual to get the most from the
meter’s wide array of capabilities. This meter is shipped fully tested and calibrated and, with
proper use, will provide years of reliable service.
Table of Contents
Warranty .................................................................................................................................. 3
Safety Information .................................................................................................................. 3
Meter Description ................................................................................................................... 4
AC + DC Voltage Measurements ........................................................................................... 5
AC Current Measurements .................................................................................................... 5
1ΦKW, KVA, KVAR, Power Factor & Phase Angle Measurement..................................... 6
3Φ3-Wire KW, HP, KVA, KVAR, Power Factor & Phase Angle Measurement.................. 7
3Φ4-Wire KW, HP, KVA, KVAR, Power Factor & Phase Angle Measurement................ 10
Resistance and Audible Continuity Measurements .......................................................... 13
Capacitance Measurements ................................................................................................ 14
Diode Tests ........................................................................................................................... 14
Temperature Measurements................................................................................................ 14
AC and DC µA Current Measurements ............................................................................... 14
Meter Control Keys............................................................................................................... 15
Automatic Sleep Mode and Battery Replacement ............................................................. 16
Specifications ....................................................................................................................... 17
Calibration, Repair, and Technical Support Services ....................................................... 20

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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.
Safety Information
•Read the following safety information carefully before attempting to operate or service the
meter.
•To avoid damage to the instrument do not exceed the maximum input limits shown in the
technical specifications.
•Do not use the meter or test leads if they appear damaged.
•Use extreme caution when working around bare conductors or bus bars. Accidental contact
with the conductor could result in electric shock.
•Use the meter only as specified in this manual; otherwise, the protection provided by the
meter may be impaired.
•Read the operating instructions before use and follow all safety information.
•Use caution when working with voltages above 60VDC or 30VAC RMS. Such voltages
represent a shock hazard.
•Before taking resistance measurements or testing continuity, disconnect the circuit under test
from the main power supply and remove all loads from the circuit.
Safety symbols
Caution! Refer to this manual before using the meter.
Dangerous voltages.
Meter is protected throughout by double insulation or
reinforced insulation.
When servicing, use only specified replacement parts.
Complies with EN-61010-1, IEC 1010-2-32

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Meter Description
1. Transformer Jaws
2. Jaw opening trigger
3. Data Hold & MX/MN button
4. Function Selector
5. Range button
6. Temperature input jack
7. LCD Display
8. ‘COM’ input jack
9. ‘V’ input jack
10. Ω
µA input jack

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Measurements
AC + DC Voltage Measurements
WARNING
The maximum input is 600V. Do no attempt voltage measurements above this limit. Exceeding
this limit could cause electrical shock and damage to the meter.
1. Set the rotary switch to the ‘ V’ position.
2. Insert the test leads into the meter’s input jacks. (Black to
‘COM’ and Red to ‘V’)
3. Connect the test leads to the measured circuit.
4. The meter will automatically detect and display AC or DC
voltage. The meter will also automatically select the
appropriate range.
5. Read the voltage (main display) and frequency (upper,
smaller display digits) on the LCD.
NOTE: The sensitivity for Automatic AC/DC Voltage detection is 1V.
Voltage below 1V may indicate DC.
NOTE: The sensitivity for voltage measurements is 1.2V and the frequency range is 40Hz to 1
KHz. If the frequency is less than 40Hz the LCD may display ‘Hz’.
AC Current Measurements
1. Set the rotary switch to the "~A" position.
2. Press the Trigger to open the jaw.
3. Fully enclose the conductor that is being measured in the jaw. No gap should exist between the
two jaw halves. The conductor under test must be a single wire; if there are multiple wires in a
cable the conductor must first be isolated (see diagram below).
4. The meter selects the range automatically.
5. Read the measured current (main display) and frequency (upper display) on the LCD.
NOTE: The sensitivity for current measurements is 6A and the frequency range is 40Hz to
400Hz. If the frequency is less than 40Hz the LCD may display ‘Hz’.

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AC Power Measurements
1ΦKW, KVA, KVAR, Power Factor & Phase Angle Measurement
1. Set the rotary switch to the ‘KW/KVA’
position.
2. Insert the test leads to the meter as
follows: Black to ‘COM’ and Red to ‘V’.
3. Connect the black lead to the neutral line.
4. Connect the red lead to the power line
and clamp onto the same lead to which
the red lead is connected.
5. The meter selects the best range
automatically.
6. Select the desired display combination
using the RANGE key. Press RANGE to
scroll through the following combination displays:
kW and HP (horsepower)
kW and PF (power factor)
kW and KVAR (reactive power)
KVA and phase angle (θ)
V and A
Note that LEAD and LAG icons are also displayed on the LCD to inform the user that the voltage is
leading or lagging the current with regard to phase.
Note: Allow 2 seconds after each RANGE key press for the meter to update the display.
1 HP = 746 Watts
PF KW
KVA
== cosθ
KVA (Apparent Power) = (V*A) / 1000
KVAR (Reactive Power) = (KVA) (KW)
22
−= KVA * sinθ
NOTES
1. The ‘+’ sign printed on the meter must face the power source for best accuracy.
2. If the device under test is a switching mode power supply, the KW, PF, and Phase angle
measurements may not be accurate.

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3Φ3-Wire KW, HP, KVA, KVAR, Power Factor & Phase Angle Measurement
1. First, measure WRS(L1L2) (refer to the diagram below).
a. Set the rotary switch to the “ V”.
b. Press and hold the “HOLD” key while setting the rotary switch to “KW/KVA”, the 3φ3W and
WL12 symbols will appear.
c. Insert the test leads into the jacks.
d. Select a phase (e.g. S or L2) as COM and connect the test probe of the COM (black)
terminal to that phase (e.g. S or L2).
e. Connect the test probe of V (red) terminal to the second phase (e.g. R or L1).
f. Clamp the same phase as step e. (e.g. R or L1).
g. The power clamp will automatically select the proper range.
h. Wait until the reading is stable (about 6 seconds). Press the “HOLD” key to store the
measured value. The WL23 symbol will appear.
2. Second, measure WTS(L3L2) (refer to the diagram that follows the steps below).
a. Disconnect the test probe from the phase where the jaw clamp was set in the previous
measurement.
b. Connect the test probe to the third phase (e.g. T or L3).
c. Clamp the third phase where test probe is connected to (e.g. T or L3)
d. The power clamp will automatically select the proper range.
e. Wait until the reading is stable (about 6 seconds) and then press the “HOLD” key to store
the measured value.

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3. The power clamp will process these two sets of data (WL12 ,WL23), and show the result on the
LCD. The WL123 symbol will be shown to indicate 3φ3W power. The 3φ3W power (in watts) is
stored in the meter memory.
4. To read a single data record, press the “ HOLD ” key to select desired WL12 , WL23 or WL123
display then press the “RANGE” key to select KW+HP (Horse Power), KW+PF (Power
Factor), KW+KVAR, KVA+θ(Phase Angle) or A+V.
5.
W3
φ
3W = WRS(L1L2) + WTS(L3L2)
WKVARW
W
KWKVA 33
2
33
2
33 φφφ +=
PF K
W
KVA
W
W
W
33
33
33
φ
φ
φ
=
6. Set the rotary switch to another position to exit this mode and clear the stored data.

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NOTE
Once a phase is selected as COM, users can not change this selection in the
subsequent measurement. For example, if S (or L2) phase is selected, S (or L2)
phase is always connected to the COM during measurement of WRS (or WL1L2) and
WTS (or WL3L2) in 3φ3W unbalanced power.
NOTE
1. The "+" sign printed on Panel must face the power source for accurate
measurement.
2. If the device under test is a switching power supply, the meter KW, PF and θ
reading maybe incorrect.
NOTE
For 3φ3W unbalanced power measurements, WRS or WTS could be negative.
Ensure that all connections are correct before accepting a reading as valid.

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3Φ4-Wire KW, HP, KVA, KVAR, Power Factor & Phase Angle Measurement
1. First, measure WR(L1) (refer to the diagram below).
a. Set the rotary switch to the “ V” position.
b. Press and hold the “RANGE” key while setting the rotary switch to the “KW/KVA” position,
the 3φ4W and WL1 symbols should appear.
c. Insert the test leads into the input jacks.
d. Connect the neutral line to the COM (black) terminal.
e. Connect the test probe of the V (red) terminal to the first phase (e.g. R or L1).
f. Clamp on to the same phase (e.g. R or L1).
g. The power clamp meter will automatically select the proper range.
h. Wait until the reading is stable (about 6 seconds) and then press the “HOLD” key; the WL1
symbol will clear and the WL2 symbol will appear in order to instruct users to take the WS(L2)
measurement.
2. Second, measure WS(L2) (refer to the diagram that follows the steps below)
a. Disconnect the test probe from the phase where the jaw was clamped in the previous
measurement.
b. Connect the test probe of the V (red) terminal to the second phase (e.g. S or L2).
c. Clamp on to the phase where the test probe is connected (e.g. S or L2 phase)
d. The power clamp will automatically select proper range.
e. Wait until the reading is stable (about 6 seconds) and then press the “HOLD” key; the WL2
symbol will disappear. The WL3 symbol will appear to instruct users to take the WT(L3)
measurement.