Regarding the method of how the multimeter measures current, the principle diagram of the current measurement by the multimeter is divided into DC voltage conversion circuit and AC voltage conversion circuit, the operation steps of the multimeter to measure the current, and the precautions for the multimeter to measure the actual current.
1. Before measuring the current, first determine the nature of the current (AC and DC) and the range of the current.
2. Select the appropriate measurement tools (such as safety, accuracy, and ease of use when measuring in the field) and measurement gear.
After selecting the appropriate measurement tool, if you are not a professional technician, but only an hobbyist, it is recommended to read the instructions for use.
3. Operation steps of multimeter for measuring current:
1) If it is a small electrical device (such as an electronic device), you can read the description of the product's electrical power in the product manual. This section explains that sometimes the range of current passed by the electrical device when it is working is directly indicated in the manual.
If the instructions only indicate the power and voltage used, the current can be calculated by the formula "A = W / V". Electrician world
When it is necessary to test the total current of multiple devices during operation, the currents of the single devices are added to calculate the total current on the main line.
If actual measurements are needed:
(1) Select the appropriate gear (measure current, current value range)
(2) Disconnect the circuit under test (but the electrical equipment and the load cannot be disconnected, otherwise the circuit is short-circuited!), Run the multimeter into the circuit (note that it is connected in series), at this time the resistance of the multimeter is almost zero, and the current flowing through the multimeter It is equal to the current flowing through the electrical equipment and the load.
2) If it is a larger type of electrical equipment (working voltage is generally 220V to 380V), it is recommended to use a clamp ammeter (multimeter).
The principle is that a closed electromagnetic field is formed on the current-carrying line, and the change of the electromagnetic field causes the multimeter to generate a current.
This current has a proportional relationship with the measured line current, so that the line current can be read directly in the ammeter.
1. Before measuring the current, first determine the nature of the current (AC and DC) and the range of the current.
2. Select the appropriate measurement tools (such as safety, accuracy, and ease of use when measuring in the field) and measurement gear.
After selecting the appropriate measurement tool, if you are not a professional technician, but only an hobbyist, it is recommended to read the instructions for use.
3. Operation steps of multimeter for measuring current:
1) If it is a small electrical device (such as an electronic device), you can read the description of the product's electrical power in the product manual. This section explains that sometimes the range of current passed by the electrical device when it is working is directly indicated in the manual.
If the instructions only indicate the power and voltage used, the current can be calculated by the formula "A = W / V". Electrician world
When it is necessary to test the total current of multiple devices during operation, the currents of the single devices are added to calculate the total current on the main line.
If actual measurements are needed:
(1) Select the appropriate gear (measure current, current value range)
(2) Disconnect the circuit under test (but the electrical equipment and the load cannot be disconnected, otherwise the circuit is short-circuited!), Run the multimeter into the circuit (note that it is connected in series), at this time the resistance of the multimeter is almost zero, and the current flowing through the multimeter It is equal to the current flowing through the electrical equipment and the load.
2) If it is a larger type of electrical equipment (working voltage is generally 220V to 380V), it is recommended to use a clamp ammeter (multimeter).
The principle is that a closed electromagnetic field is formed on the current-carrying line, and the change of the electromagnetic field causes the multimeter to generate a current.
This current has a proportional relationship with the measured line current, so that the line current can be read directly in the ammeter.