What is the process for using a low resistance ohmmeter to measure contact resistance and continuity?

2 Why use a low resistance ohmmeter?

A low resistance ohmmeter is useful for testing the contact resistance and continuity of various electrical components and devices, such as circuit breakers, switches, relays, transformers, bus bars, cables, joints, and terminations. By measuring the contact resistance and continuity, you can assess the condition and integrity of your electrical connections and circuits, and identify any potential problems or faults that may cause overheating, arcing, power loss, or failure. A low resistance ohmmeter can also help you verify the quality and accuracy of your installation, maintenance, and repair work.

3 How to prepare for the test?

Before you use a low resistance ohmmeter to measure contact resistance and continuity, you need to follow some safety precautions and preparation steps. First, you need to isolate and de-energize the circuit or connection under test, and lock out and tag out any sources of power. Second, you need to inspect the circuit or connection for any signs of damage, corrosion, or looseness, and clean and tighten any terminals or connectors as needed. Third, you need to select the appropriate test leads and clamps for your LRO, and ensure that they are in good condition and free of dirt or oxidation. Fourth, you need to set up your LRO according to the manufacturer's instructions and specifications, and calibrate it if necessary.

4 How to perform the test?

To use a low resistance ohmmeter to measure contact resistance and continuity, you need to connect the test leads and clamps to your LRO and the circuit or connection under test, making sure that the clamps are securely attached. Then, turn on your LRO and select the desired test current and resistance range, as well as adjusting other settings depending on your LRO model and test requirements. Press the start button or trigger to initiate the test, and your LRO will measure the voltage drop across it. Record the test results and compare them with the expected or acceptable values for your circuit or connection, repeating the test several times if necessary. Finally, disconnect the test leads and clamps from your LRO and from the circuit or connection under test, turn off your LRO, and store it safely.

5 How to interpret the results?

The results of using a low resistance ohmmeter to measure contact resistance and continuity depend on the type and condition of your circuit or connection, as well as the standards and criteria that you are following. Generally, lower resistance values and higher continuity levels indicate better electrical performance and reliability, while higher resistance values and lower continuity levels indicate worse electrical performance and reliability. However, you need to consider other factors, such as temperature, humidity, contact pressure, and surface area, that may affect the resistance and continuity measurements. You also need to consult the manufacturer's data sheets, manuals, or guidelines for your circuit or connection to determine the normal or acceptable ranges of resistance and continuity values. If your results are outside these ranges, you may need to troubleshoot, repair, or replace your circuit or connection to prevent any issues or hazards.