Extech Instruments 382075 User manual

User's Manual
Model 382075
3φ/1φPower Clamp-on Meter
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Introduction
Congratulations on your purchase of the Extech Model 382075 Auto Range Power Clamp-On Meter.
Careful use of this device, will provide years of reliable service.
Meter Functional Description
1. Transformer Jaw
Used to sense current signal. To measure current or power,
the conductor under test must be fully enclosed by the jaw.
2. Transformer Trigger
Press to open the jaw.
3. Data Hold Button
Press to freeze most recent reading on the LCD. Press
again to release.
4. Function Select and On/Off Switch
Select desired function, such as KW, V, A, KVA, or 3φ.
5. LCD Display
4-digit (9999 count) display with function symbols, units,
decimal point, low battery icon, and zero indication.
6. Units Symbols
Once a function is selected, the corresponding unit (KW, V,
A, Phase, KVA, or 3φ) will be displayed.
7. 3φ3W and 3φ4W Select Button
If the 3φsystem is not a balanced system, users can press
this button to select 3φ3W, 3φ4W or a balanced system.
Once the button is pressed, the LCD displays 3φ3W or
3φ4W depending on the function selected.
8. Read/Next Button
•When the rotary switch is set to the 3φfunction, the READ/NEXT button is used as a NEXT button.
In the 3φbalanced mode, pressing the NEXT button will display W+PF, KVA+KVAR, or V+A data.
•In the 3φ3W mode, pressing the NEXT button stores the measured values WRS(L1L2) and WTS(L3L2).
After two values are measured and stored, the meter adds the two values, displays the result with
the symbol WRST to represent W3φ3W. To start another W3φ3W measurement, press the NEXT button
again.
•In the 3φ4W system mode, press the NEXT button to store the measured values WR(L1), WS(L2) and
WT(L3). After three values are measured and stored, the meter adds the three values, displays the
result with the symbol WRST to represent W3φ4W. To start another W3φ4W measurement, press the
NEXT button again.
•If the rotary switch is not set to the 3φfunction, the READ/NEXT button is used as a READ button.
Stored data in memory (saved by pressing the REC button) can be read by pressing READ.
9. & 10. V and COM Input Terminals
Used as positive and negative (common) inputs for voltage measurements.
11. DC A/W ZERO button
Press this button once to zero the Amp or Watt display. While the meter is zeroing, the word ZERO
appears the LCD.
12. REC button
Press the REC button to store up to 4 data points in meter memory.
Figure 1
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Operating Instructions
NOTE: Ensure that the jaws are clear of any conductors before applying power to the meter. The
meter performs an auto zero upon power-up to null any residual magnetism. If this is done with a
conductor inside the jaw area, the auto zero function will cause subsequent measurements to be
inaccurate.
DC/AC 1 φ 2W Power (W) and Power Factor (PF) measurements
1. Apply power to the meter with the jaws clear of
any conductors.
2. Set the rotary switch to the Watts function
(KW).
3. If the watt reading is not zero, press the
DCA/DCW ZERO button once to zero it.
4. Insert the test leads into the input terminals.
5. Connect the COM (black) terminal to the
neutral line.
6. Connect the V (red) terminal to the power line.
7. Clamp on to the line where the V (red) terminal
is connected. The power clamp will
automatically select the proper measurement
range. Read the Watt and PF (Power Factor)
values displayed on the LCD.
NOTE: The "+" sign printed on jaw must face the power source for accurate measurements.
AC/DC Voltage Measurements
Voltage (V) and Frequency (Hz) Dual Display
WARNING: Maximum input voltages: 1000VDC and 750VAC. Do not attempt to measure voltage
that exceeds these limits.
1. Set the rotary switch to the Voltage position (V).
2. Insert the test leads into the input terminals.
3. Connect the test leads in PARALLEL with the circuit to be
measured.
4. The power clamp will automatically select the proper range.
5. Read the voltage and Frequency values displayed on the LCD.
NOTE: The sensitivity for voltage/frequency measurements
is 1V, and the frequency range is 10 - 400Hz. If the
frequency is < 10 Hz, the LCD will indicate 0 Hz. If the
frequency is > 400 Hz, LCD will show OL.
Voltage(V) / Current (A) Dual Display
Follow the instructions in the section entitled "3φBalanced Power
Measurements" to monitor V and A simultaneously.
Figure 3
1 Phase
Load
1 Phase 2 Wire Current >
Figure 2
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AC/DC Current Measurements
Current (A) + Frequency (Hz) Dual Display
WARNING:
1. When applying power to the meter, make sure the clamp jaws are not near a conductor.
2. Make sure that test leads are disconnected from the meter during current measurements.
1. Set the rotary switch to the Amps position (A).
2. Push and hold the DCA/DCW ZERO button to zero the reading.
3. Press the trigger to open the jaw and fully enclose the conductor
to be measured. The Jaws must be completely closed to make a
measurement (see Fig.4).
4. Read the current/frequency values on the LCD.
NOTE: The sensitivity for current/frequency measurement is
5A, and the frequency range is 10 - 400Hz. If the frequency is
< 10 Hz, the LCD will display 0 Hz. If the frequency is > 400
Hz, LCD will display "OL".
Voltage (V) and Current (A) Dual Display
Follow the instructions in the section entitled "3φBalanced
Power Measurements" to monitor Voltage and Current simultaneously.
DC/AC 1 φ 2W Apparent/Reactive Power Measurements (KVA+KVAR)
NOTE: Before taking any measurements, zero the current (A) reading and set the rotary switch to
the KVA position.
Follow the steps listed in section entitled DC+AC 1φ2W Power (W) and Power Factor (PF)
measurement for these measurements. KVAR is a calculated value, and its accuracy greatly depends
on the accuracy of the V, A, and KW readings. To obtain a more accurate KVAR value when PF is
greater than 0.91 (φ< 25°), measure the phase angle and obtain the KVAR from the following equation
for a pure sine wave:
KVAR = KVA * sin φ
Phase Angle Measurements
1. Set the rotary switch to the A position. If the current reading is not zero, press the DCA
ZERO button.
2. Set the rotary switch to the Phase position.
3. Insert the test leads into the input jacks.
4. Connect the test lead inserted in the COM (black)
terminal to the reference line.
5. Connect the test lead connected to the V (red)
terminal to the voltage signal under test.
6. Clamp on to the wire where the V (red) terminal is
connected (see Fig.5).
7. If current signal is detected from the jaws, the
phase angle will be displayed in degrees on the
LCD together with the frequency of the voltage.
8. If current is not detected, only the frequency of the
voltage will be displayed while the phase angle
display will be left blank.
NOTE: Zero the current (A) reading before measuring to avoid incorrect Phase Angle readings.
Figure 4
XL
1 Phase
Load
1 Phase 2 Wire Current >
Figure 5
V
A
-23.8
o
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INDUCTIVE LOAD: A negative phase angle indicates that the current signal lags the voltage
signal. A negative phase angle also indicates an inductive load.
CAPACITIVE LOAD: A positive phase angle indicates that the current signal leads the voltage
signal. A positive phase angle also indicates a capacitive load.
NOTE: The "+" sign printed on the clamp jaw must face the power source for correct readings.
3 φ Balanced Power Measurements
Power (W) and Power Factor (PF) Dual Display
1. Apply power to the meter with the jaw clear of any
conductors.
2. Set the rotary switch to the 3φposition.
3. The LCD will show 3φ3W, 3φ4W, and BAL
symbols to indicate balanced mode.
4. If the watt reading is not zero, press the DCA/DCW
ZERO button once to zero reading
5. Insert the test leads into the input terminals.
6. Select one phase (R or L1) as COM and Connect
the COM (black) terminal to the same phase just
selected (R or L1).
7. Connect another test lead to the second phase (S or L2). See Fig. 6.
8. Clamp on to the third phase (T or L3).
9. The power clamp will automatically select proper range.
10. Read the Watt and PF values displayed on the LCD.
11. To view the KVA and KVAR data, press the NEXT button.
12. To view V and A, press the NEXT button again.
13. To return to the W and PF display, press the NEXT button again.
KVA/KVAR Dual Display
Follow steps 1 through 10. in the above section and press the NEXT button. Wait approx. 2 seconds
for the LCD to display the KVA and KVAR.
Voltage (V) and Current (A) Dual Display
Follow steps 1 through 10 in the above section and press the NEXT button twice. Wait approx. 2
seconds for the LCD to display Voltage (V) and Current (A).
NOTE: Specific selection of each phase is not required in 3φbalanced power measurement
mode. As long as each test lead and the jaws are connected to different phases, the reading is
always correct. The "+" sign printed on jaw must face the power source for accurate
measurement.
NOTE: To find out if a load is capacitive or inductive, refer to the section entitled "Phase Angle
Measurements".
3 φ 3W Unbalanced Power Measurements
Two measurements WRS (or WL1L2) and WTS (or WL3L2) are required. Refer to Fig. 7.
1. First measure WRS (or WL1L2)
a. Apply power to the meter with the jaw clear of any conductors.
b. Set the rotary switch to the 3φposition.
c. Press the 3φbutton once, the 3φ3W symbol will display on the LCD. At this moment, the WRS
symbol flashes prompting the user to begin measurement of WRS.
d. If the watt reading is not zero, press the DCA/DCW ZERO button once to zero reading
e. Insert the test leads into the input terminals.
Bal. Load
3-phase
3 Phase 4 Wire
R(L1)
S(L2)
T(L3)
N
Current >
Figure 6
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f. Select one phase (S or L2, for example) as COM and connect the COM (black) terminal to that
phase (S or L2).
g. Connect V (red) terminal to the second phase (R or L1).
h. Clamp on to the same phase as in step g. (R or L1).
The power clamp will automatically select the proper range.
i. Wait until the reading stabilizes, then press the NEXT button. The WRS (WL1L2) symbol will
disappear. At this moment, WRS is stored in memory, and the WT(WL3L2) symbol appears
flashing to prompt the user to take the WTS (WL3L2) measurement.
2. Secondly, measure WTS (or WL3L2 ). Refer to Fig. 8.
a. Disconnect the test leads and jaws from the lines in the previous measurement.
b. Connect the test leads to the third phase (T or L3).
c. Open and close the jaws, be sure that no conductor is in the jaws.
d. If the watt reading is not zero, press the DCA/DCW ZERO button once to zero the reading.
e. Clamp on to the third phase where the test lead is connected (T or L3)
f. The power clamp will automatically select proper range.
g. Wait until the reading stabilizes, then press the NEXT button. The WT(or WL3L2) symbol will
disappear. At this moment, WTS (or WL3L2) data are stored in memory,
Once the NEXT button is pressed (after measurements of WRS (or WL1L2) and WTS (or WL3L2)), the power
clamp will add the two values and display the result on the LCD. The WRST symbol appears indicating
that the reading shown is the wattage of the 3φ3W unbalanced Power. PF is not shown in the 3φ3W
unbalanced power mode.
NOTE: Once a phase is selected as the COMMON connection, users cannot change this
selection in the subsequent measurements. For example, if S (or L2) phase is selected, S (or L2)
phase is always connected to the COM of the power clamp during measurements of WRS (or
WL1L2) and WTS (or WL3L2) in 3φ3W unbalanced power mode.
NOTE: The "+" sign printed on the jaw must face the power source.
NOTE: In the 3φ3W unbalanced power measurement mode, WRS or WTS could be a negative
value. Users must make sure all the connections are correct to obtain correct power readings.
W3φW= WRST = WRS(L1L2)+ WTS(L3L2)
3 Phase
Load
3 Phase 3 Wire
Cur rent >
FIGURE 7
R(L1)
S(L2)
T( L3 )
W
RS (L1L2)
3 Phase
Load
3 Phase 3 Wire
Current >
FIGURE 8
R(L1)
S(L2)
T( L3 )
W
TS (L3L2)
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3 φ 4W Unbalanced Power Measurements
The measurements of WR(or WL1), WS(or WL2), and WT(or WL3) are required for these measurements.
1. First, measure WR(or WL1) (Fig. 9).
a. Apply power to the meter with the jaw clear of any conductors.
b. Set the rotary switch to the 3φposition.
c. Press the 3φbutton twice, and the 3φ4W symbol appears singularly on the left side of the LCD.
The WRsymbol will flash prompting the
user to take the WR. measurement
Note: If the watt reading is not zero, press the
DCA/DCW ZERO button once to zero
reading
d. Insert the test leads into the input terminals
e. Connect the neutral line to the COM
(black) terminal.
f. Connect the V (red) terminal test lead to
the first phase (R or L1).
g. Clamp on to the same phase (R or L1).
h. The power clamp meter will automatically
select the proper range.
i. Wait until the reading is stable, then press
the NEXT button. The WRsymbol will disappear. Now, WRis stored in the memory, and the WS
symbol flashes prompting the user to take the WSmeasurement.
2. Measure WS(or WL2) (Fig. 10).
a. Disconnect the test leads from the phase
where the jaw was clamped onto as
described in the section entitled "3φ3W
unbalanced power measurements".
b. Connect V (red) terminal to the second
phase (S or L2).
d. If the watt reading is not zero, press the
DCA/DCW ZERO button once to zero
reading
e. Clamp onto the phase where the test
lead is connected to (S or L2 phase)
f. The power clamp will automatically select
the proper range.
g. Wait until the reading stabilizes, then press the NEXT button. The WSsymbol will disappear. WS
is now stored in memory.
3 Phase
Load
3 Phase 4 Wire
Current >
FIGURE 9
R(L1)
S(L2)
T( L3 )
W
R (L1)
N
3 Phase
Load
3 Phase 4 Wire
Current >
FIGURE 10
R(L1)
S(L2)
T( L3 )
W
S (L2)
N
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3.Thirdly, measure WT(or WL3). See Fig. 11.
a. Disconnect the test lead from the phase
where the Jaw was connected in the
section entitled "3φ3W Unbalanced
Power Measurements".
b. Connect the test lead inserted in the V
(red) terminal to the third phase (T or
L3 phase).
d. If the watt reading is not zero, press the
DCA/DCW ZERO button once to zero
reading
e. Clamp onto the phase where test lead
is connected to (T or L3).
f. The power clamp will automatically
select the proper range.
g. Wait until the reading stabilizes, then
press the NEXT button. The WTsymbol will disappear and WTwill be stored in memory,
4. Once the NEXT button is pressed (after measurements of WRWS, and WT), the power clamp will add
the three values WR, WS, and WTtogether and display the result on the LCD. The WRST symbol will
appear indicating that the reading shown is the wattage of the 3φ4W unbalanced circuit. PF is not
shown in the 3φ4W unbalanced power measurement mode.
NOTE: The "+" sign printed on jaw must face the power source.
NOTE: In the 3φ4W unbalanced power measurement mode, all three WRor WSand WTreadings
must be positive. If one is negative, check the connection of the test leads and the clamping of
jaw. Make sure test lead and clamp connections are correct to obtain useful power readings.
W3φW= WRST = WR(L1)+ WS(L2)+ WT(L3)
3 Phase
Load
3 Phase 4 Wire
Current >
FIGURE 11
R(L1)
S(L2)
T( L3 )
W
T (L3)
N
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1 φ 3W Power Measurement
1φ3W power measurements are similar to 3φ3W unbalanced power measurements except that the
nomenclature is different. Two measurements of WRS (or WL1G) and WTS (or WL2G) are required
1. First, measure WRS (or WL1G). See
Fig.12.
a. Apply power to the meter with
the jaw clear of any conductors
b. Set the rotary switch to the 3φ
position.
c. Press the 3φbutton once, and
the 3φ3W symbol will singularly
appear on the left side of the LCD.
The WRS symbol will flash
prompting the user to measure
WRS(L1G).
d. If the watt reading is not zero,
press the DCA/DCW ZERO button
once to zero it.
e. Insert the test leads into the input terminals.
f. Connect the COM (black) terminal to ground.
g. Connect the V (red) terminal to the second phase (L1).
h. Clamp on to the same phase as connected in step g. (L1).
i. The power clamp will automatically select the proper range.
j. Wait until the reading stabilizes, then press the NEXT button. The WRS (WL1G) symbol will
disappear and the WRS(L1G) reading will be stored in memory. The WT (WL2G) symbol will flash
prompting the user to take WTS (WL2G)
measurements.
2. Secondly, measure WTS (or WL2G). Fig. 13.
a. Disconnect the test leads from the
phase where the jaws were clamped
onto in the previous measurement.
b. Connect the test lead to the L2 line.
d. If the watt reading is not zero, press
the DCA/DCW ZERO button once to
zero reading
e. Clamp on to the L2 line where the
test lead is connected.
f. The power clamp will automatically
select the proper range.
g. Wait until the reading is stable, then
press the NEXT button. The WT(or
WL2G) symbol will disappear. At this
moment, WTS (or WL2G) is stored in the
memory,
3. Once the NEXT button is pressed after measurements of WRS (or WL1G) and WTS (or WL2G) are taken,
the power clamp will add the two values together and show the result on the LCD. The WRST symbol
will display along with the wattage of the 1φ3W unbalanced Power. PF is not shown in 1φ3W
unbalanced power mode. See equation below.
W1φW= WRST = WRS(L1G)+ WTS(L2G)
1 Phase
Load
1 Phase 3 Wire
Current >
FIGURE 12
1 Phase
Load
L1
G
L2
W
L1
1 Phase
Load
1 Phase 3 Wire
Current >
FIGURE 13
1 Phase
Load
L1
G
L2
W
L2
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Calculation of 3 φ 4W Power Factor (PF)
When measuring 3φ4W unbalanced power, use the REC button to record the individual power factors
(KWR(L1), PFR(L1), KWS(L2), PFS(L2), KWT(L3), and PFT(L3)) of each phase in memory. 3φ4W power factor can
be calculated using the following equation:
Improving the Power Factor of a 3 φ 4W Power System
Measure the KVARR(or KVARL1), KVARS(or KVARL2 ), and KVART(or KVARL3) values of each phase.
Based upon the measured values, a 3φor 1φcapacitor at the rated voltage and frequency can be used
to improve the power factor. To find the value of capacitance, refer to the following equation.
Where:
f: frequency in Hz
V: phase voltage
It is recommended that the KVAR value of the capacitor a somewhat less than the value measured.
Improving the Power Factor of a 3 φ Balanced Power System
1. Measure the KVAR 3φvalue of a balanced system.
2. Based upon the measured value, a 3φcapacitor at the rated voltage and frequency can be used to
improve power factor.
3. To find the value of capacitance, refer to the equation in the section above.
4. It is recommended that the KVAR value of the capacitor be somewhat less than the value
measured.
Improving Power Factor of a 1 φ 2W Power System
1. Measure KVAR value of a 1φ2W power system.
2. Based upon the measured value, users can purchase required capacitor at rated voltage and
frequency to improve power factor.
3. If value of capacitance is needed, obtain the value via the equation in the section entitled
"Improving Power Factor of 3-phase 4-wire System".
4. It is recommended that the KVAR value of the capacitor should be a little less than the value
measured.
NOTE: The indication of phase sequence is not limited to 3φbalanced power. It can be used in
general as long as the Power Factor is greater than 0.1.
KVAR(L1)=KWR(L1)
PFR(L1);KVAS(L2)=KWS(L2) PFS(L2);KVAT(L3)=KWS(L3) PFT(L3)
KVA3φW= KVAR(L1)+ KVAS(L2)+ KVAT(L3)
PF3φW= KW3φW
KVA3φW
Capacitance(Farad) = KVAR*1000
2πfV2
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