Types and structure of ammeters
Ammeters can be divided into two forms: pointer ammeters and digital ammeters. Pointer ammeter generally consists of dial, needle, dial, zero device, etc.; digital ammeter through the display screen to directly display the current value. Whether it is pointer type or digital ammeter, its basic principle is through the magnetic field generated by the current on the measuring coil pointer or induced current to produce the corresponding voltage, so as to measure the strength of the current.
1.Preparation
Before using an ammeter, you first need to do some preparatory work.
(1) Choose a suitable ammeter: choose a suitable ammeter according to the range of current to be measured, and make sure that the range of the ammeter can cover the required measurement range.
(2) Check the safety of the circuit: make sure that the circuit to be measured is in a safe state, without damage or leakage and other problems. At the same time, the circuit should be kept energised to maintain normal measurement.
(3) Calibration of the ammeter: Before using the ammeter, it is advisable to calibrate it to ensure the accuracy of the measurement results.
2. Connecting the circuit
Connecting an ammeter involves installing it on a branch line in a circuit to measure the current through that branch line. When connecting an ammeter, the following points should be noted:
(1) Disconnect the circuit: Before connecting the ammeter to the circuit, the circuit should be disconnected.
(2) Choose the appropriate connection: the ammeter can be connected in series or parallel to the circuit, and the choice of the appropriate connection can depend on the circumstances.
(3) Maintain good contact: Use pins or crocodile clips to connect the positive and negative terminals of the ammeter to the circuit firmly and maintain good contact.
3.Zeroing and adjusting the range
After connecting the circuit, you need to zero and adjust the range.
(1) Zeroing: Adjust the ammeter to zero, that is, no current flow when the pointer indicates the zero position on the scale, zeroing is to eliminate errors and improve the accuracy of measurement.
(2) Adjust the range: Adjust the range of the ammeter according to the current range to be measured. Too small a range may cause the pointer to deflect too much, and too large a range will reduce the sensitivity of the ammeter.
4. Read the measured value
According to the state of the circuit, turn on the power switch to energise, and the current starts to flow through the ammeter. According to the ammeter display, you can know the current size.
(1) Reading: When the current passes through the ammeter, the pointer will be deflected and the digital ammeter will display the corresponding current value.
(2) Note the unit: the unit of current is usually Ampere (A), and milliampere (mA) and other units may appear as needed.
