Classification of electrical measuring instruments
In the field of electrical technology, electrical measuring instruments play a very important role.
The role of electrical instruments is to measure various electrical parameters, such as current, voltage, period, frequency, electrical power, power factor, resistance, inductance, capacitance, etc. Electricians can understand the technical performance and working conditions of the electrical equipment of the circuit by measuring the values of these electrical parameters, so that they can make appropriate treatments and necessary adjustments to ensure the normal operation of the circuit and the safe operation of the equipment. Therefore, electricians must master the principles and methods of use of common electrical instruments.
Classification of electrical measuring instruments
Mainly divided according to the principle of action and purpose. Everyone just needs to understand.
According to different purposes: it can be divided into voltmeter, ammeter, power meter, watt-hour meter, etc.; according to the type of current, it can also be divided into three types: DC meter, AC meter and AC/DC dual-purpose meter, as well as the ability to measure current, Multimeter with functions such as voltage and resistance.
According to the principle of action: there are four commonly used types: magnetoelectric, electromagnetic, electric and induction, and others include vibration, thermoelectric, hot wire, electrostatic, rectifier, photoelectric and electrolytic.
According to the measurement method: it can be divided into two types: direct reading and comparison. Instruments that directly indicate the measured value are called direct-reading instruments, such as voltmeters, ammeters, power meters, etc.; instruments whose measured values are compared with "standard quantities" are called comparative instruments, such as balanced bridges and compensation器等。 The chapter on electrical instruments here mainly introduces direct-reading instruments.
According to accuracy: it can be divided into seven types: 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, and 5.0. The allowable error of the 0.2 level meter is 0.2%, the 0.5 level meter error is 0.5%, and so on. The accuracy of the instrument above 0.5 level is higher, and it is mostly used in the laboratory as a calibration instrument. The accuracy of class 1.5 and class 2.5 are low, and they are generally installed on the switchboard and console to monitor the allowable conditions of electrical equipment.
