Detection of underreporting EXPERIENCE ELECTRICAL ENERGY

Accounting for electricity is an integral part of any enterprise. First of all, it is necessary for the implementation of monetary calculation between the power supply organization and consumers. достоверной информации о количестве потребленной (выданной)электрической энергии. The main purpose of the commercial accounting of electricity - to provide accurate information on the quantity consumed (issued) of electricity. In three-phase four-wire systems for the measurement of consumed electricity used three-element electronic meters, which are the wattmeter measurement system and belong to an integrating instrument. 2 – t 1 , определяется как: The meter is a device, which is responsive not only to the value of energy, but also on the direction of transmission, so when you connect the counter to ensure the correct direction of the currents and the correct combination with the stresses in each element schetchika.Aktivnaya energy meter measured at time t 2 - t 1 is defined as:

where the subscript "f" denotes the phase voltage and the magnitude of underreporting toki.Opredelim electricity at some of the most common faults of elements of the measuring complex metering errors, and connection of electricity.

Ток во вторичной цепи равен нулю, предположим в фазе, обозначенной индексом «1» (I 1ф = 0). Break the circuit and the secondary winding of current transformer (CT). Current in the secondary circuit is equal to zero, we assume a phase marked by the letter "a» (I 1F = 0). With balanced load active energy, measured by meter, according to (1):

ie is 2/3 of the actual value. отсутствии напряжения на одном из элементов счетчика (на параллельной обмотке счетчика). Перепутана маркировка в токовых цепях , вследствие чего поменялись местами провода, идущие от ТТ, допустим фазы с индексом «2». The same magnitude of underestimation is observed in the absence of voltage on one of the elements of the counter (on the parallel winding counter). Confused markings in the current circuits, resulting in reversed the wires coming from the TT, for example the phase with index "2". In this case, current flows in all phases, but in a phase of "2" is in the opposite direction. 0 , следовательно, энергия, учитываемая счетчиком: In other words, the vector diagram (Fig. 1), the current phase of the "2" is rotated by 180 0, and hence the energy meter taken into account:

Векторная диаграмма токов и напряжений на счетчике при подключении ТТ фазы "2" с обратной полярностью при активно-индуктивной нагрузке. Figure 1. Vector diagram of currents and voltages at the counter when you connect the TT phase "2" with reversed polarity in the active-inductive load.

ie with balanced load is 1/3 of the actual value.

To verify the connection of the counter is enough to remove the vector diagram and the building, to compare it to expected that depends on the nature of the load. Vector diagrams of the most convenient devices to remove or VAF VAF-85M-A. To obtain a reliable measurement result, the vector diagram must be removed directly from the meter terminals, which are usually located under the seal of the energy supplying organization, so you can use a simplified method of verification, which is necessary to: measure all the phase voltages and currents passing through the primary windings of all phases of the TT, determine the full capacity by the formula:

- Measure the number of revolutions of the disk count or the number of active power indicator light pulses (in electronic or microprocessor-based meter) N in time T (enough for 30-60 seconds), then determine the active power by the formula:

ТТ – коэффициент трансформации ТТ; n – передаточное число счетчика. where K CT - CT ratio; n - ratio meter. In the presence of reactive energy meter, to make the measurement of reactive power Q, and calculate it using the formula similar to (5), as well as to determine the full power of "Counter"

- Compare the values ​​of the total capacity as defined by the formulas (4) and (6), which should coincide with the correct connection count and the healthy elements of the measuring complex accounting of electricity. f ) раз. In the absence of reactive energy meter compares the values ​​of S and P, which, when properly connected meter should differ by no more than a Cos (f) time. С помощью предложенных несложных измерений и вычислений можно сделать вывод о правильности подключения электросчетчика и исправности измерительного комплекса учета электроэнергии (трансформаторов тока, измерительных цепей от ТТ до счетчика, параллельной обмотки счетчика, цепей напряжения), а также о величине недоучитываемой электроэнергии. The smallest error, alteration load achieved with "simultaneous" measurement of phase currents and the frequency of rotation of the disk meter. With the proposed simple measurements and calculations can be concluded about the correctness of the meter connection and serviceability of measuring complex accounting of electricity (current transformers, measuring circuits from the TT to counter parallel to the winding counter circuit voltage), and underestimate the magnitude of electric power.