How to Measure Electric Current Using a Multimeter
Step 1: Selection and preparation of multimeter
Firstly, choose a suitable multimeter. Usually, we can choose a multimeter with a current range 1.5-2 times larger than the measured current. Then, carefully read the user manual of the multimeter to understand its functions and usage methods. Finally, ensure that the battery of the multimeter is properly installed and sufficient to ensure normal operation.
Step 2: Circuit disconnection
Before measuring the current, it is necessary to ensure that the circuit has been disconnected. This is very important because connecting or disconnecting the current measurement circuit before the circuit is disconnected may result in arcing and excessive current, causing harm to equipment and personal safety.
Step 3: Select the appropriate current gear
Select an appropriate current gear based on the approximate range of the measured current. If the measured current exceeds the range of the multimeter, a larger range should be selected, otherwise the measurement result will be inaccurate. For example, if the expected current is between 10mA and 1A, the 200mA gear can be selected first, and then adjusted according to the specific situation.
Step 4: Connection of current measurement terminal
Connect the red probe to the current measurement socket on the multimeter, usually the A or mA socket. Insert the measuring black probe into the COM socket. Next, connect the red and black measuring probes to two different ports on the circuit to ensure a secure connection.
Step 5: Close the circuit and take measurements
Measure the current through a multimeter by merging the two disconnected ports of the circuit. Before closing the circuit, it is essential to ensure that no personnel touch any exposed conductors to prevent electric shock accidents caused by current passing through the human body. Meanwhile, it is also necessary to pay attention to or ensure that other components in the circuit (such as resistors, capacitors, inductors, etc.) do not have a significant impact on the measured current.
Step 6: Reading and Recording
Read and record the measured value based on the scale and digital display on the multimeter. If using an analog multimeter, pay attention to the line of sight position when reading to avoid visual errors. If a digital multimeter is used, the measurement value is usually displayed directly on the screen. To ensure the accuracy of the reading results, the range selection of the multimeter can be adjusted appropriately.
Step 7: Disconnect and restore the circuit
After the measurement is completed, be sure to disconnect the circuit first, then unplug the red and black measuring probes and remove them from the circuit. Restore the connection status of the circuit and ensure that all components, wires, and plugs are connected correctly and reliably.
