Basic knowledge of electrical instrumentation

Electrical instruments play an extremely important role in the installation, use and maintenance of electrical circuits and electrical equipment. In the decoration work of electronic appliances, the multimeter plays a special and important role. This article will focus on the proper use of the multimeter and enable the student to operate more proficiently through professional training. Secondly, the basic measurement principle and correct use method of clamp ammeter, megohmmeter, etc. are introduced.

The basic knowledge of the first section of electrical instrumentation

Learning the basics of electrical instrumentation is the basis for the proper use and maintenance of electrical instruments. This section describes the classification of common electrical instruments, panel symbols, accuracy levels, and the basic structure of general electrical instruments.

First, the classification of commonly used electrical instruments is more:

Electrical instruments are divided into ammeter (ampere meter), voltmeter (voltmeter), power meter (watt meter), electricity meter (kWh meter), ohmmeter, etc. according to different measuring objects; according to the working principle of the meter Magnetoelectric, electromagnetic, electric, inductive, etc.; according to the type of electricity to be measured, it is divided into AC meter, DC meter, AC/DC meter, etc.; it is divided into fixed type according to the nature of use and device method. Plate type), portable type; according to the error level, it is divided into 0.1 level, 0.2 level, 0.5 level, 1.0 level, 1.5 level, 2.5 level and 4 levels.

Second, the electrical panel commonly used panel symbol

The panel of the electrician's instrument marks various symbols indicating the technical characteristics of the instrument. These symbols indicate the conditions of use of the meter, the range of electrical parameters, structure and accuracy level measured, which provide an important basis for the selection and use of the meter.

Third, the accuracy of electrical instruments

The accuracy level of an electrician's instrument refers to the percentage of the basic error that may be generated when the instrument is used under specified conditions. It indicates the size of the basic error of the meter. Among the above seven error levels, the smaller the number, the higher the accuracy and the smaller the basic error. Class 0.1 to class 0.5 meters have higher accuracy, and are mostly used for laboratory inspection instruments. Classes below 1.5 are less accurate and are used for engineering inspection and measurement.

The so-called basic error refers to the error caused by the defects of the internal structure and quality of the instrument under normal use conditions. This is the inherent error of the meter itself. For example, the basic error of a 0.5-level ammeter is 0.5 / 100 of full scale. If the measured current is 100A, the actual current value is between 99.5 and 100.5A.

Fourth, the basic structure of commonly used electrical instruments

Commonly used electrical instruments are mainly made of bakelite or iron or hard plastic, panels with scales and symbols, measuring lines (simple meters), head electromagnetic systems, pointers, dampers, shafts, bearings, springs , zero adjuster and other components.

Fifth, the maintenance of electrical instruments

1. Strictly follow the instructions, save and use in the temperature, humidity, dust, vibration, electromagnetic field and other conditions.

2. After long-term storage, the meter should be energized regularly to check and remove moisture.

3. After long-term use of the instrument, the necessary inspection and correction shall be carried out according to the electrical measurement requirements.

4. Do not disassemble and debug the instrument at will, otherwise it will affect its sensitivity and accuracy.

5. For the instrument with battery in the table, pay attention to check the discharge condition of the battery. If it is not user, it should be replaced in time to avoid the battery electrolyte overflowing and corroding the machine. For instruments that are not used for a long time, the battery inside the watch should be taken out.

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