Measuring current transformers. Production.
►prospects and economic efficiency of using amorphous iron transformers
In November 2009, the first session of the Energy Club was held in Minsk. It considered the concept of energy security of the Republic of Belarus until 2020. 4 main directions of its strengthening were identified:
1) Energy independence - maximum refusal to import electricity;
2) Diversification of supplies both by types of resources and by countries;
3) Reliability of power supply (creation of reserve stocks of fuel);
4) Energy efficiency (improving mechanisms for stimulating energy saving, reducing the energy intensity of GDP, increasing the efficiency of using fuel and energy resources based on scientific and technological advances, increasing costs for energy saving).
In the conditions of the formation of the energy market, there is an objective need to improve the commercial metering of electrical energy. Commercial metering of electricity using measuring current transformers in 0.4 kV distribution networks of power supply organizations and consumers currently requires radical modernization and involves replacing class 0.5 measuring current transformers with 0.5s class current transformers (instruction letter of the Belenergo Concern No. 09 / 171 dated 19.02.2002). The specified current transformers, according to the interstate standard GOST 7746-2001, provide the limits of permissible errors in a wider range of primary current measurement: their current error is 0.5% for 20-120% I1nom, 0.75% for 5-20% I1nom and 1 , 5% for 1-5% I1nom. This allows, in conditions of recession and fluctuations in consumer loads, to reduce the share of commercial losses of electricity, which is determined by instrumental underreporting. Various models of measuring current transformers of the specified class, included in the State Register of Measuring Instruments of the Republic of Belarus, are presented on the market of metering and metering instruments in the republic. These products are in many respects similar in their declared technical characteristics, but in fact, as established by tests and operating experience, they are not equivalent in the long term of their use. On the instructions of the Belenergo concern (order of the concern dated May 29, 2003 No. 112), BelTEI RUE, together with the accredited testing center of the branch PSDTU RUE Grodnoenergo, tested a number of samples of measuring current transformers of domestic and foreign manufacturers. 25 samples of measuring current transformers manufactured in Russia, Belarus, Lithuania and Ukraine have been tested.
Based on the test results and their analysis, specialists have confirmed the clear and indisputable advantages of measuring current transformers with cores made of nanocrystalline alloys over measuring current transformers with cores made of electrical steel.
a) resistance of metrological characteristics to direct current magnetization;
b) high electrical resistance of the material and reduced by 4-10 times the losses due to eddy currents and magnetization reversal of the core;
c) double technological margin for accuracy class;
d) long service life with preservation of metrological characteristics (and thus a potentially larger calibration interval);
e) smaller dimensions and weight of the core.
Taking into account the tests carried out and based on the operating experience of measuring current transformers for distribution networks of 0.4 kV, the Belenergo concern sets technical requirements for measuring current transformers, in addition to the requirements of GOST 7746-2001.
Instrument current transformers.