User Guide Precision Milliohm Meters Models 380460 and 380462
Introduction Congratulations on your purchase of the Extech Milliohm Meter Model 380460 (110V) or Model 380462 (220V). The milliohm meters are enclosed in rugged carrying cases for durability. Measurements are made with Kelvin test leads (supplied) for optimal accuracy in five (5) selectable ranges. Careful use of this meter will provide years of reliable service. Meter Description 1. LCD Display 7 2. Zero adjust knob 3. Range Dial 6 8 4. Power switch 5. 200m select switch 6. AC power cord 7.
Operation Basic Principles of 4-wire Measurements For each range, the meter provides a specific amount of test current (refer to General Specifications) which flows from the HI to the LO meter terminal and therefore from the HI to the LO clip lead (Refer to the diagram). This is the current that ultimately passes through the device under test (RX in diagram below). Once the test current is applied to the device under test, clip leads Rx1 & Rx2 measure the voltage drop across the device under test.
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.
Specifications General Specifications Circuit Custom one-chip LSI microprocessor circuit Display 18 mm (0.7") LCD with 2000 display counts Measurement terminals 4-Terminal Kelvin type Measurement ranges Five (5) ranges (200m, 2, 20, 200, 2000 ohms) Zero Adjust ±50 count adjustment Sampling Time Approximately 0.4 seconds Over input indication Indication of "1 " Operating Temperature 0 °C to 50 °C (32 °F to 122 °F) Operating Humidity 80% Relative Humidity max.
