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Three new national measurement standards in GUM

The President of the Central Office of Measures recognized three new national measurement standards, i.e.:

1. The national standard of AC voltages ratio at 50 Hz;

2. The national AC voltage standard;

3. The national standard of AC currents ratio at 50 Hz.


Developing and maintenance of the national measurement standards and other measurement standards of the highest measurement units reproduction accuracy class on the national level are inter alia two of the basic tasks of every National Metrology Institute which in Poland is the Central Office of Measures. The national measurement standards ensure a reference basis for many areas of the national economy including most of the of industry, trade, health, life and environment protection branches and the area of the security and public order protection, consumer rights protection. They are important during customs and pre-packaged goods control etc. as well. Together with other measurement standards the national measurement standards build up a chain of connections which are linked to dissemination of measurement units. This chain ensures the measurement uniformity necessary for the whole country.

The national standard of AC voltages ratio at 50 Hz

The national standard of AC voltages ratio at 50 Hz - a measurement station in a laboratory

The national standard of AC voltages ratio at 50 Hz consists of gas capacitor of type NK 400, two air capacitors of type 3330/10000 and air capacitor of type 3330/2000. The nominal voltage is: (1÷400) kV and the nominal value of the voltage ratio is: 40:1 or 400:1.

The AC voltages ratio at 50 Hz is an electrical quantity with wide scope of applications in the electricity production. The basic area of application of the measurement standards which reproduce AC voltages ratio - the so called inductive voltage instrument transformer - is the measurement of the electric power (with the parallel usage of the electricity meters) at electric power producers facilities (power plants) and in electric power transmission from the energy producers to the customers (high, medium and low voltage power supply networks). The electricity meters, because of their parameters, are not able to measure this power directly. For this reason there is a need to apply special kind of measuring system including an interface element – the inductive voltage instrument transformer which is connected with power grid and electricity meter working at low voltage level of the secondary power transformer. The exact measurement of the electricity power in the power grids is essentially important to identify the energy losses in transmission. The financial settlements between energy industry, energy producers and big energy customers take place on the basis of the measurement system indications.

The exact measurement of the above mentioned quantities is also applied in the process of inductive voltage instrument transformer production. These devices have to meet specific requirements, particularly regarding accuracy. The accuracy is also essential for research and calibrating laboratories for which the source of traceability are the standards maintained by GUM.


The national AC voltage standard

The national AC voltage standard

The national AC voltage standard is a measuring system used for very exact transfer of the AC voltage by comparing its effective values with the exact known values of the DC voltages. It consist of two sets of the thermal voltage converters of AC/DC voltage: electronic converter which serves to transfer the voltage in the range from 22mV to 700 mV, one set of three thermal voltage converters of AC/DC voltage and five range resistors which serves to transfer voltages in the range from 1 V to 1000 V. Thanks to these converters it’s possible to transfer the AC voltage at frequencies from 10 Hz to 1 MHz.

The AC voltage is one of the main electrical quantities which is inseparably linked to the quantities in the field of electronics, electrical engineering and electricity. This quantity is very important for different areas of the national economy. The AC voltage is used in measurements of other physical quantities (in particular RLC measurements) and non-electrical quantities – e.g. in the precise sensors converting the non-electrical quantities to the electrical ones including converting to the AC voltage - the inductive proximity sensors.

Both above mentioned standards have been working in GUM since 19th December 2014. Previously they used to have a status of the reference standards.


The national standard of AC currents ratio at 50 Hz

The national standard of AC currents ratio at 50 Hz - a measurement station in a laboratory

The national standard of AC currents ratio at 50 Hz consists of: comparator type 4764, auxiliary comparator type 4781, and power transformer type NCD 200. The AC currents ratio at 50 Hz is an electrical quantity widely applied in the electricity branch.

The basic area of usage of the measurement standards reproducing AC currents ratio, the power transformer, is the measurement of the electric power (with the parallel usage of the electricity meters) at the electric power producers facilities (power plants) and in electric energy transmission from the energy producers to the customers (high, medium and low voltage power supply networks).

There is a demand for receiving of accurate measurement results for high voltage and currents electric energy. The electricity meters, because of their parameters, are not able to measure this power directly. For this reason there is a need to apply special kind of measuring system including an interface element – the power transformer connected with power grid and electricity meter working at low current value level of the secondary power transformer. The exact measurement of the electricity power in the power grids is essentially important to identify the energy losses in transmission.

The financial settlements between energy industry, energy producers and big energy customers take place on the basis of measurement system indications.

The exact measurement of the above mentioned quantities is applied in power transformers production. These devices have to meet specific requirements, particularly regarding accuracy. The accuracy is also essential for research and calibrating laboratories for which the source of measurements uniformity are the standards
maintained by GUM.

The above mentioned standard has been working in GUM since 30th January 2015. Previously it used to have a status of reference standard.


Summary

At the moment the Central Office of Measures maintains 18 national measurement standards and reference standards of the highest unit of measures reproduction accuracy class.

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