Mainly divided based on the principle of action and purpose. Everyone just needs to understand.
According to different purposes: it can be divided into Voltmeter, Ammeter, power meter, Electricity meter, etc; According to the type of current, it can also be divided into three types: DC meter, AC meter, and AC DC dual meter. There are also multimeter functions that can measure current, voltage, resistance, and so on.
According to the principle of operation, there are four commonly used types: magnetoelectric, electromagnetic, electric, and induction. Other types include vibration, thermoelectric, hot wire, electrostatic, rectifier, photoelectric, and electrolytic.
According to measurement methods, it can be divided into two types: direct reading and comparative reading. Instruments that directly indicate the measured value are called direct reading instruments, such as Voltmeter, Ammeter, power meter, etc; An instrument that compares the measured values with a "standard quantity" is called a comparative instrument, such as a balance bridge, compensator, etc. The section on electrical instruments here mainly introduces direct reading instruments.
According to accuracy, it can be divided into seven levels: 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, and 5.0. The allowable error for level 0.2 instruments is 0.2%, for level 0.5 instruments, it is 0.5%, and so on. Instruments above level 0.5 have high accuracy and are often used as calibration instruments in laboratories. Levels 1.5 and 2.5 have low accuracy and are generally installed on distribution boards and control consoles to monitor the allowable conditions of electrical equipment.