Extech Instruments 380580 User manual

User’s Guide
Model 380580
Battery Powered
Milliohm Meter
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
Back to the Extech 380580 Product Page

Version 2.0 1/05
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Introduction
Congratulations on your purchase of Extech’s Model 380580 Battery Powered Milliohm
Meter. This device offers five resistance ranges with resolution as low as 0.1mΩ. The 4-wire
Kelvin clip connection ensures optimum accuracy. Typical applications include transformer,
motor coil, and PC Board resistance measurements. This professional meter, with proper
care, will provide years of safe reliable service.
Specifications
General Specifications
Display 1.0" (25 mm) LCD (1999 counts)
Measurement terminals 4-Terminal Kelvin type
Measurement Range Five ranges (see listing below)
Sampling Time Approximately 3 times per second
Over input indication Indication of "1 - - -"
Operating Temperature 5ºF to 131ºF (-15ºC to 55ºC)
Operating Humidity <80% RH
Power Supply 8 x 1.5V AA Batteries
Weight 3.3 lbs (1.5kg)
Dimensions 9.8x7.5x4.3" (250x190x110 mm) with cover
Range Specifications
Range Resolution Test Current Accuracy Open Circuit Voltage
200.0mΩ0.1mΩ100mA ± 0.5% + 2 digits 4.2V
2000mΩ1mΩ100mA ± 0.5% + 2 digits 4.2V
20.00Ω0.01Ω10mA ± 0.5% + 2 digits 4.2V
200.0Ω0.1Ω10mA ± 0.5% + 2 digits 4.3V
2000Ω1Ω1mA ± 0.5% + 2 digits 4.4V
International 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

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Meter Description
1. Current Terminals
2. Potential Measurement Terminals
3. LCD Display
4. Start/Stop Test Button
5. Range Select/Power Switch
6. LED Error Lights
• No Test/Over Temperature
• RPVoltage Regulation
• RCCurrent Regulation
7. Current/Range Table
Leads
Current Leads- Banana plug to alligator clip
C1- Green
C2- Blue
Voltage Potential Leads- Banana plug to alligator clip
P1- Red
P2- Black
Kelvin Clips- Banana Plugs (2) to Kelvin Clip
Red (P1) Green (C1)
Black (P2) and Blue (C2)
Measurement Considerations
1. Do not apply voltage to the meter input terminals. Meter damage may result.
2. Always insure that the circuit to be measured is switched OFF, isolated and
completely de-energized before connecting the test leads.
3. If the Over Temperature LED (NO TEST) indicator is lit, allow the instrument to
cool down before proceeding further.
4. The RCled indicates when the test current falls out of regulation. Selecting a higher
range may eliminate the condition.
5. The RPled indicates when the voltage on the device under test is too high.
Selecting a lower range may eliminate the condition.
6. If either the RCor RPled is on, the measurement may be in error.
7. The current terminals are fuse protected.
8. Keep the potential test leads as short as possible. Long leads may introduce noise.
9. When using the four separate alligator clip leads always place the current leads
outside the potential leads.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com

Version 2.0 1/05
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Preliminary Checks
Current Regulation Check
1. Connect the current leads C1and C2to the meter.
2. Set the function switch to the 200.0mΩrange.
3. Momentarily press the TEST RPbutton. The meter
will intermittently beep and RC will light
4. Short the current leads C1to C2.
5. The RCLED should go off, indicating that the meter
is operating correctly.
6. Momentarily press the TEST RPbutton to stop the test
7. The meter will return to NO TEST status.
Voltage Measurement check
1. With the current test leads C1and C2 shorted,
connect and short the potential (voltage) leads P1
and P2.
2. Set the Function switch to the 200.0mΩposition.
The NO TEST status LED will light.
3. Momentarily press the TEST RPbutton. (the meter
will intermittently beep)
4. The display should indicate 00.0
5. Momentarily press the TEST RPbutton to stop the test.
The NO TEST status LED will light.
6. Remove the shorts from P1and P2, and C1and
C2and
7. Short the test leads P1to C1and P2to C2
8. The RPLED as well as the NO TEST status LED
should light indicating an over-voltage or over-range
9. Turn the rotary selector switch to OFF
Polarity check
1. Short the test leads P1to C2and P2to C1together.
2. Set the Function switch to the 200.0mΩposition.
3. The “-1“ negative indicator should appear in the
display.
Operation check
Use the Kelvin clips for this test
1. Short the all the leads (P1, P2,C2,C1) together.
The P1, P2,C2,C1 order is important.
2. Set the Function switch to the 200.0mΩ
position. The NO TEST status LED will light.
3. Momentarily press the TEST RPbutton. (the
meter will intermittently beep
4. The display should indicate near 00.0
(depending on the test clip connections) and
both RPand RCLEDs should remain off.
5. Momentarily press the TEST RPbutton to stop
the test.
Note: These tests can be performed on any range.

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Measurement Procedure
1. Select the desired measuring range on the meter. If the resistance of the device is
unknown, start with the highest range and work downward.
2. Clip the test leads onto the device under test. Note: When using the 4-wire/4
alligator clip test leads, it is recommended that the current test leads be outside of
the potential test leads (as shown in the diagram below).
3. For a short test duration of 10 seconds, press the TEST RPbutton for less than 2
seconds. This EnerSave™ feature can be used to conserve battery power.
4. For a long test duration of 60 seconds, press the TEST RPbutton for more than 3
seconds.
5. During the test, the meter will intermittently beep. At the end of the test or if the test
is stopped, “HOLD” will appear and the last reading will be “frozen” on the display.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com

Version 2.0 1/05
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Measurement Principles
The test current flows through the resistance from the Current+ (C+) terminal to the
Current - (C-) terminal. The P+ and P- (POTENTIAL) terminals measure the voltage drop
across the device under test only, thus eliminating the lead and contact resistances. The
meter displays the resistance based on the test current and the measured voltage; refer to
the equation below:
Rx = Vx / Is
Where:
Vx is the voltage drop across the device under test;
Is is the test current;
Rx is the resistance of the device under test.
Thermal Effects
Temperature can have a significant effect on the performance of millohmeter due to the
temperature coefficient of the resistance under test and thermal EMF’s across dissimilar
conductors.
Most conductors have a large temperature coefficient of resistance
For example: 0.4%/°C for copper. A cooper conductor that has a resistance of 10.00m ohm at
20°C will increase to 10.40m ohm at 30°C. This should be taken into account..
A current going through a resistance will also elevate the temperature so duration of the test
can also change the resistance.
C+
C-
P+
P-
Current
Volts

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BATTERY INSTALLATION
WARNING: To avoid electric shock, disconnect the test leads from any source of voltage
before removing the battery cover.
1. Turn power off and disconnect the test leads from the meter.
2. Open the rear battery cover by removing two screws (B) using a slotted head
screwdriver.
3. Insert the batteries into battery holder, observing the correct polarity.
4. Put the battery cover back in place. Secure with the screws.
REPLACING THE FUSES
There are three fuses:
Power Supply Fuse
1. The power supply fuse is located in the battery compartment.
2. Remove the two screws to open the battery compartment.
3. Always use a fuse of the proper size and value.
Current Circuit Fuse
1. Fuse protection for the current terminals.
2. If the fuse is blown, the RCLED will stay on.
3. The fuse is located under the printed circuit board.
4. There are 4 mounting screws that have to be removed.
5. Two screws are located under the black feet on the bottom of the unit.
6. The other two screws are located in the battery compartment.
7. Remove the battery compartment door and the batteries to access these screws.
8. Always use a fuse of the proper size and value.
Potential Circuit Fuse
1. Fuse protection for the potential terminals.
2. If the fuse is blown, the RPLED will stay on.
3. The fuse is located under the printed circuit board.
4. There are 4 mounting screws that have to be removed.
5. Two screws are located under the black feet on the bottom of the unit.
6. The other two screws are located in the battery compartment.
7. Remove the battery compartment door and the batteries to access these screws.
8. Always use a fuse of the proper size and value.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX [phone] - TestEquipmentDepot.com