SU1257532A1 - Current-to-voltage converter - Google Patents

Abstract

The invention relates to electrical measuring technology and can be used to convert non-temporal current to alternating voltage in various measuring devices where high measurement accuracy is required. The aim of the invention is to improve the accuracy of the conversion. A device containing a primary current transformer 1 with a compensating capacitance 14, a primary winding 4 and a measuring winding 7, in order to achieve the share due to additional computation of the magnetizing force of the primary current transformer winding 22, n additional current transformers, on ferromagnetic serotics there are primary, measuring, basic 1 and compensating and auxiliary 1b 5e compensating windings, which correspond to the number of an additional current transformer, counting Vym additional current transformer, directly follows the main. The device achieves a more complete compensation of the magnetizing force of the primary winding of the subsequent current transformer, which allows to significantly improve the accuracy of the controlled current to voltage converter. The use of a device allows to significantly reduce the requirements for amplifiers. 1 Il. CS & JV Sddd d.

Description

one

The invention relates to electrical measuring equipment and can be used to convert alternating current into alternating current 1 April; in various measuring devices where high measurement accuracy is required, for example, when taking into account electrical energy,

The purpose of the invention is to increase the point 1257532 .2

winding 7 is amplified by amplifier 10 and converted by a resistor 13 into a current that flows through series-connected compensating windings 14,15,16 ... and performs the main compensation of the magnetizing forces of the primary windings A, 5j6., .. of all and two transformers current. Due to the limited odds

20

This is due to the additional gain of the amplifier 10 to complete compensation of the magnetizing force of the primary current transformer winding.

The drawing shows a block diagram of the proposed device.

The device contains current transformers 1,2,3 ... t, the primary windings 4,5,6 ... of which are connected in series according to, their measuring windings 7,8,9 ... connected to the inputs of amplifiers 10,11,12 ,,,. A compensating winding 14 is connected to the output of the amplifier 10 through a resistor 13, respectively, with which the compensating windings 15, 16 ... of additional current transformers 2,3i..n are connected. A compensating winding 18 is connected to the output of amplifier 11 through a resistor 17, the compensating windings 19 ... of current transformers 3 ... 1 are connected in series with which, and to the output of amplifier 12, a compensating winding 21 is connected through a resistor 20

the compensation of the magnetizing forces of the primary windings 4,5,6 ... does not occur, and the non-compensated part of the magnetizing force of the primary winding 4 creates that voltage value on the measuring winding 7, under the action of which the previously achieved current value in the compensating windings 14, 15, 16 is maintained ...

Additional compensation of the magnetizing forces of the primary windings 5,6 ... is made by the output current of the amplifier 1 1, the value of which is proportional to the voltage on the measuring 25 winding 8 of the current transformer 2, the latter in turn is determined by the difference between the magnetizing force of the primary winding 5 and the sum of the magnetizing forces of the compensating windings 15 and 18. The current of the compensating winding 18 flows through the compensating windings 19 ... of the subsequent current transformers and, summing up with the magnetizing force of the compensating

thirty

therefore, according to which the co-35 windings are 16,21.,., the additional combinate m-e compensating windings, one from each subsequent current transformer. Other compensating windings of the remaining current transformers are connected in a similar way, and the free terminals of all the compensating windings of the nth current transformer are connected to the input of the converter 22.

The device works as follows.

When a controlled alternating current flows through the primary windings of 4,5,6 ... current transformers 1,2,3 ..., their ferromagnetic cores are magnetized. In this case, the alternating magnetic flux arising in the core of the current transformer 1 causes a voltage to appear on the measuring winding 7, the value of which is determined by the magnetizing force of the primary winding 4. The voltage removed from the meter 7532 .2

winding 7 is amplified by amplifier 10 and converted by a resistor 13 into a current that flows through series-connected compensating windings 14,15,16 ... and performs the main compensation of the magnetizing forces of the primary windings A, 5j6., .. of all and two transformers current. Due to the limited coefficient

Amplifier amplifier gain 10 full

the compensation of the magnetizing forces of the primary windings 4,5,6 ... does not occur, and the non-compensated part of the magnetizing force of the primary winding 4 creates that voltage value on the measuring winding 7, under the action of which the previously achieved current value in the compensating windings 14, 15, 16 is maintained ...

Additional compensation of the magnetizing forces of the primary windings 5,6 ... is made by the output current of the amplifier 1 1, the value of which is proportional to the voltage on the measuring winding 8 of the current transformer 2, the latter in turn is determined by the difference between the magnetizing force of the primary winding 5 and the sum of the magnetizing forces of the compensating windings 15 and 18. The current of the compensating winding 18 flows through the compensating windings 19 ... of the subsequent current transformers and, summing up with the magnetizing force of the compensating

0

five

0

five

the sensation of magnetizing forces of the primary windings 6 ... current transformers 3 ... p.

Subsequent additional compensation of the magnetizing forces of the primary windings of subsequent current transformers is carried out in the same way. Therefore, in each subsequent current transformer, additional compensation of the magnetizing force of the primary winding occurs with an accuracy determined by the gain of the corresponding amplifier. Amplifier converter 22 amplifies and converts the sum of the currents of the compensating windings of the last (nth) current transformer into a voltage that is the output signal of the device.

Thus, in the proposed device, a more complete compensation by the magnetizing CHni.i primary winding of each subsequent stage (its

31257

current transformer, which allows to significantly improve the accuracy of the controlled current to voltage converter in comparison with the prototype.

The use of the proposed device for converting current into voltage allows one to significantly reduce the requirements for amplifiers (the latter can be used with a loop gain factor k i 100, which is easy to achieve even with negative feedback). At the same time, the use of amplifiers with lower gain provides greater stability to the operation of the tS device.

Claims (1)

Invention Formula Current-to-voltage converter containing the main current transformer on which the primary ferromagnetic core is located, the 25 gauge and the main compensating winding, the amplifier and the resistor, the measuring winding is connected to the amplifier input, and one output of the main compensating winding through the specified “resistor connected to its output, characterized in that, in order to improve the accuracy of the conversion, it is additionally introduced into it amplifier-converter, p additional current transformers, on ferromagnetic cores of which Editor M. Petrov Compiled by S. Veysky Tehred L.Oleynik Proofreader L. Obruchar Order 4912/42 Circulation 728 Subscription VNIIPI USSR State Committee according to inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Prooktna, 4 -5 you tS 20 25, „ five 532 4 there are primary, measuring, main compensating and additional compensating windings, the number of which corresponds to the number of the additional current transformer, considering first the additional current transformer immediately following the main transformers, the amplifiers and resistors by the number of additional current transformers, the measuring winding in each additional current transformer connected to the input of the corresponding amplifier, and the main compensating winding through one of the additional resistors connected enen to its output, the primary windings of all current transformers are connected in series according to, all tri-e (where t is 1, 2, 3 ...) additional compensating windings of additional current transformers are connected in series in accordance with chains, one of which terminals are separately connected to the second conclusions of the main compensating windings of the previous current transformers, their second conclusions, formed by the conclusions of the additional compensating windings of the nth additional current transformer, and the second conclusion of its main compensating motor ki connected to the input of amplifier -preobrazovatel, wherein the number of turns of the compensating coils further current transformers same and equal number of turns of the main current transformer core compensating coil.