How are electrical appliances classified?

Electrical instruments are the general name of technical tools needed in electromagnetic measurement. Commonly used electrical instruments are divided into indicating instruments, comparison instruments, digital instruments and circuit detection devices, recording instruments and oscilloscopes, range expansion devices and converters.

Electrical instruments are divided into ammeter (ammeter), voltmeter (voltmeter), power meter (wattmeter), watt-hour meter (watt-hour meter), ohmmeter, etc. According to the different working principles of the instrument, it can be divided into magnetoelectric system, electromagnetic system, electric system and induction system. According to the different types of measured electricity, it can be divided into AC meter, DC meter and AC /DC dual-purpose meter. According to the different nature of use and device mode, it can be divided into fixed (switch board), portable and intelligent; According to the different error grades, it is divided into seven grades: 0. 1, 0.2, 0.5, 1.0, 1.5, 2.5, 5.0 * *. The smaller the number, the smaller the instrument error and the higher the accuracy level.

Measurement learning method

First, associative memory method

For pointer instrument, measuring mechanism is its core; For digital instruments, the digital basic table is its core. Through the radial correlation of the measuring mechanism, the basic situation of the instrument can be seen at a glance. Such as indicating instrument core → measuring mechanism → five-part device → four series instruments → structure, principle, technical characteristics, precautions in use, representative objects, etc. That is, the measuring mechanism is led out by the pointer core, which is divided into five parts according to the different functions of its components. Three of these five devices are torque devices, which are related to the structural characteristics of four series of instruments through the characteristics and components of three torques, and then to various instruments. Such as: magnetoelectric ammeter, voltmeter, electromagnetic ammeter, voltmeter, ammeter, frequency meter, phase meter, induction watt-hour meter. In addition, it is equipped with multimeter with magnetoelectric system as measuring mechanism, transformer clamp ammeter, megohmmeter with magnetoelectric system ratio meter as measuring mechanism, one-arm bridge with magnetoelectric system as galvanometer, clamp ammeter with electromagnetic system as measuring mechanism, etc.