Extech Instruments 380460 User Manual page 4

Measurement Equations
Vx = Is x Rx;
Where Vx is the voltage (measured by the meter) across the device under test; Is is the
test current; Rx is the resistance of the device under test. From Vx = Is x Rx, the meter
moves to the next step which is: Rx = Vx/Is. With this equation the meter determines the
resistance of the device under test. Note that the measured resistance (Rx1 & Rx2) is not
affected by stray resistance since the test current is supplied directly to the device under
test. This is the advantage of the 4-wire Kelvin lead configuration over 2-wire methods
which introduce errors into low resistance measurements.
International Symbols
Powering the Meter
Connect the meter to the correct power source (110 or 220VAC); the Model 380460 uses
110VAC and the Model 380462 uses 220VAC (note that these meters are NOT
interchangeable). Do not apply voltage to the meter input measurement terminals. Meter
damage may result.
Measurement Procedure
1. Rotate the Range select switch to the 200m range to prepare for zeroing. Ensure that
200m is selected on the 200m select switch.
2. Perform a Zero Adjustment per the following:
• Short the Kelvin Clips as shown in the diagram below.
• Rotate the Zero Adjust Knob until the meter indicates zero units.
3. Select the desired measuring range via the rotary Range select switch. When using the
200m range, put the 200m select switch to the 200m position; for all other
measurements put this switch in the opposite position.
4. Either clip the leads onto a component or clip the leads between two points in a circuit.
5. Observe the meter reading.
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
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4 Model 380460 and 380462 Version 2.1 March 2005