RU89242U1 - ELECTRIC ENERGY TRANSFORMER METER - Google Patents

Abstract

A transformer electric energy meter, the input voltage circuit of which contains a secondary circuit of a voltage measuring transformer, including a secondary main measuring winding, and which also contains an electronic part and a power supply, the first end of the secondary main measuring winding and the first input of the power supply being connected to a common point of the electronic part , the second end of the secondary main measuring winding is connected to the voltage measuring input of the electronic part, the supply bus of which yuchena to the output power supply unit, characterized in that the secondary circuit of the voltage transformer introduced additional secondary power coil having a first end connected to a common point, and its second end is connected to the input of the power supply.

Description

The proposed utility model relates to electrical engineering and can be used to build transformer electricity meters (EE).

Known transformer meter EE (Electrical measurement. General course. Edited by A.V. Fremke, L. "Energy", 1973. P. 172, Fig. 118), in which the secondary winding of the measuring voltage transformer (ITN) is connected parallel to the winding voltage measuring part of the counter. It contains a secondary ITN winding connected in parallel with the counter voltage winding.

However, the specified transformer meter consumes more power from the secondary winding of the ITN (GOST R 52321-2005, clause 7.1.1.), Which can be 3 W and 12 VA. On the other hand, ITN errors increase with increasing load in the PITH secondary circuit (V.O. Arutyunov, Electrical Measuring Instruments and Measurements. SEI M.L. 1958, p. 325, formula 15-13). An additional negative error in the measurement of EE also appears due to the voltage drop from the load current on the connecting wires that connect the secondary winding of the ITN to the counter.

In addition, an EE transformer meter is known (- Anthony Collins, “An inexpensive electric energy meter on an AD7755 chip” - AN559R (translation) Fig. 2, p. 2), which contains an ITN voltage measuring transformer, an electronic part of the EC and a power supply unit, with the input the counter voltage circuit contains a secondary (measuring) ITN winding, the first end of which and the first input of the power supply are connected to a common point (ground) of the electronic part, the second end of the secondary winding is connected to the power supply and to the voltage-measuring input of the EC, bus Tania is connected to the power supply output.

However, such a construction of the input voltage circuit of the transformer counter leads to an increase in the power consumed by the meter from the secondary ITN circuit mainly due to the power supply. For example, in AN-559R, Figure 2, mentioned above, the load is a capacitor through which an alternating current flows, the average value of which is approximately equal to the power supply current of the EC. Although the consumption of the Echo meter may be small, but since the current flows from the output of the secondary winding of the ITN, the output voltage of which is usually 100 V, the total consumption of the meter from the ITN, expressed in VA, can exceed the consumption of the EC by tens of times compared with power consumption of the EC from the power supply unit (supply voltage of the EC 3 ... 5 V).

The objective of the invention is to reduce the power consumption of the transformer EE counter from the secondary circuit of ITN.

The task is achieved in that in the transformer counter EE, the input voltage circuit of which contains the secondary circuit of the voltage measuring transformer, including the secondary main measuring winding, the electronic part and the power supply, the first end of the secondary main winding and the first input of the power supply connected to a common point ( ground) of the electronic part, the second end of the main measuring winding is connected to the voltage measuring input of the electronic part, the power bus of which is connected to the output of the unit power supply, an additional secondary power winding is introduced into the secondary circuit of the voltage measuring transformer, the first end of which is connected to a common point, and the second end is connected to the second input of the power supply, which is connected to the common point by one end and connected to the PSU input by the other end, In this case, the secondary main (measuring) winding of an ITN is connected at one end to a common point, and at the second end it is connected to a measuring input of the voltage of the electronic counter, which is connected to a common point, and its power bus is attached Dinen to the output of the power supply.

The drawing shows a functional diagram of the proposed transformer counter EE.

It contains:

1 - measuring voltage transformer (ITN);

2 - primary winding ITN;

3 - secondary main (measuring) winding of ITN:

4 - secondary additional (power) winding of the Ign;

5 - power supply unit (BP) of the counter;

6 - electronic part (ECH) of the counter;

7 - measuring input voltage of the electronic counter:

8 - power bus of the counter;

9 - common point (ground) of the counter.

The first end of the secondary winding 3 and the first input of the power supply unit 5 are connected to a common point (ground) 9 of the electronic part of the power supply 6, the second end of the secondary main winding 3 is connected to the voltage-measuring input 7 of the electronic part 6, the power bus 8 of which is connected to the output of the power supply 5, the first end of the additional secondary supply winding 4 is connected to a common point 9, and the second end of the winding 4 is connected to the second input of the PSU 5.

The proposed counter works as follows.

Measuring voltage transformer 1 performs accurate scale conversion of the high-voltage input voltage (phase, linear) to the output voltage of a standard level, taken from the secondary 3 of the main winding of the ITN, which is supplied to the voltage measuring input 7 and is used by the meter to measure EE. From the secondary secondary winding 4, the voltage is removed, which is used by the BP 5 of the counter to generate the supply voltage supplied to the power bus 8 of the counter. Common point 9 has zero potential. Potentials at the counter nodes are counted from it. In the electronic part 6 of the counter, the EE is measured, processing and display of the measurement results, information is transmitted via communication channels, etc. Voltage is measured from the output of the secondary main winding 3 to the measuring input 7 of the electronic part 6 of the counter, which is proportional to the primary voltage of ITN 1, which is equal to the voltage measured energy efficiency. This voltage is then used by the meter to measure EE. To provide a supply voltage 6 of the electronic part, the alternating voltage from the output of the additional winding 4 is supplied to the power supply 5, where it is converted to a constant supply voltage, and then fed to the power supply bus 8 EH.

Thus, the introduction of a secondary secondary winding 4 into the voltage circuit of the transformer counter allows you to reduce its output voltage to a level sufficient for the power supply unit 5. In modern meters, this is several (3 ... 5) volts. While the output rated voltage of the secondary main winding 3 is usually 100 V, which is tens of times higher than the voltage of the additional winding 4. The power consumed by the proposed transformer counter from the secondary ITN circuit will decrease by the same amount compared to the prototype, because in it, the power supply is connected to the output of the main measuring secondary winding, and consumes the same current as the power supply 5 from the additional winding 4 in the proposed utility model. For example, if the electronic part 6 of the meter consumes 0.01 A, and the output rated voltages of windings 3 and 4 are 100 V and 5 V, respectively, then the power consumed by the meter from the secondary ITN circuit in the prototype is 1 VA, and in the proposed utility model - 0.05 VA. The resistance from the side of the voltage measurement input 7 can be (0.5 ... 1) MΩ or more (AN-559R, Fig. 43, this resistance exceeds 0.5 MΩ). Therefore, in the proposed utility model, the load on the ITN is close to idle, which ensures the minimum errors of the ITN (V.O. Arutyunov ... see above, formula 15-13, p. 325).

Claims (1)

A transformer electric energy meter, the input voltage circuit of which contains a secondary circuit of a voltage measuring transformer, including a secondary main measuring winding, and which also contains an electronic part and a power supply, the first end of the secondary main measuring winding and the first input of the power supply being connected to a common point of the electronic part , the second end of the secondary main measuring winding is connected to the voltage measuring input of the electronic part, the supply bus of which yuchena to the output power supply unit, characterized in that the secondary circuit of the voltage transformer introduced additional secondary power coil having a first end connected to a common point, and its second end is connected to the input of the power supply.