Studying electrical measurements

STUDYING ELECTRICAL MEASUREMENTS

Erkaboyev Abrorjon Xabibullo o’g’li (assistant - Fergana polytechnic institute)
Annotation. This article provides information on the principle of operation of electrical measuring instruments, their types, scope of application in this area, analog and digital measuring instruments.

Keywords. Measuring device, physical quantity, measure, comparator.
1. INTRODUCTION

The concept of "measuring device" is one of the most important in theoretical metrology. A measuring device as a technical means used in measurements and having normalized metrological properties. A measuring device is a technical instrument (or their complex) intended for measurements, having normalized metrological characteristics, reproducing and (or) storing a unit of a physical quantity, the size of which is assumed unchanged (within the specified error) for a known time interval. This definition reveals the metrological essence of measuring instruments, which consists in the ability to store (or reproduce) a unit of physical quantity (PQ) and in the invariability of the size of the stored unit over time. The first makes it possible to perform a measurement, the essence of which, as you know, consists in comparing the measured value with its unit. The second is fundamentally necessary, since when changing the size of the stored PQ unit using this measuring device, it is impossible to obtain a result with the required accuracy. [1]

A measuring device is a generalized concept that unites the most diverse structurally complete devices that implement one of two functions:

- reproduce a value of a given (known) size - for example, a weight - a given mass, a resistance box - a series of discrete resistance values;

- generate a signal (indication) that carries information about the value of the measured quantity. The readings of the measuring device (MD) are either directly perceived by the human sensory organs (for example, the readings of a dial or digital instrument), or they are inaccessible to human perception and are used for conversion by other MD.

The measuring device used in various fields of science and technology is extremely diverse. However, for this set, some common features inherent in all MD can be distinguished, regardless of the field of application. According to the role performed in the system for ensuring the uniformity of measurements, MD are divided into:

- metrological, intended for metrological purposes of reproducing a unit and (or) its storage or transfer of the size of a unit to a working MD;

- workers used for measurements not related to the transfer of the size of units.

The overwhelming majority of MD used in practice belong to the second group. Metrological measuring instruments are very few in number. They are developed, produced and operated in specialized research centers. According to the level of automation, all MDs are divided into three groups:

- non-automatic;

- automated, performing in automatic mode one or part of the measurement operation;

- automatic, performing automatic measurements and all operations related to the processing of their results, registration, data transmission or the generation of control signals.

According to the level of standardization, measuring devices are divided into:

- standardized, manufactured in accordance with the requirements of the state or industry standard;

- not standardized (unique), designed to solve a special measurement problem, for which there is no need to standardize the requirements.

The bulk of MD are standardized. They are mass-produced by industrial enterprises and are subject to mandatory state tests. Non-standardized measuring devices are developed by specialized research organizations and are produced in single copies. They do not pass state tests, their characteristics are determined during metrological certification. [2]

In relation to the measured physical quantity, measuring devices are divided into;

- the main ones are the MD of the physical quantity, the value of which must be obtained in accordance with the measuring task;

- auxiliary - this is the MD of that physical quantity, the influence of which on the main measuring device or the measuring object must be taken into account in order to obtain the measurement results of the required accuracy. The MD classification according to the role in the measurement process and the functions performed is the main one and is shown in Fig. 1.