SU842665A1

SU842665A1 - Dc calibrator

Info

Publication number: SU842665A1
Application number: SU792746220A
Authority: SU
Inventors: Василий Александрович Яцук; Евгений Иванович Шморгун
Original assignee: Львовский Ордена Ленина Политехническийинститут
Priority date: 1979-04-04
Filing date: 1979-04-04
Publication date: 1981-06-30

Description

1one

Изобретение относитс к электроизмерительной технике и может быть Использовано в устройствах, в которых необходимо получение р да точно установленных значений посто нного тока, н ример дл проверки амперметров и вольтметров.The invention relates to electrical measuring equipment and can be used in devices in which it is necessary to obtain a number of precisely set values of direct current, for example, for checking ammeters and voltmeters.

Известен калибратор посто нного тока, содержаищй батарею гальванических элементов и переменные резисторы 1 .A DC calibrator is known, containing a battery of galvanic cells and variable resistors 1.

Недостатком известного устройства вл етс трудоемкость установлени калиброванных значений тока, так как дл этого необходимо периодически измер ть падение напр жени на образцовом сопротивлении, включенном в выходную цепь калибратора, и вычисл ть значение тока, зависимость тока от величины сопротивлени нагрузки, а также вли ние переходных сопротивлений и контактных ЭДС регул торов тока . .A disadvantage of the known device is the laboriousness of establishing calibrated current values, since for this it is necessary to periodically measure the voltage drop on the reference resistance included in the output circuit of the calibrator, and to calculate the current value, the dependence of the current on the load resistance, as well resistances and contact emf current regulators. .

Наиболее близким по технической (сущности и достигаемому ффекту кпредлагаемому вл етс устройство, содержащее магнитный компаратор тока, выполненный в виде трансформатора,регулируема обмотка которого подключена к источнику посто нного тока, аThe closest in technical terms (the essence and the achieved effect to the proposed one is a device containing a magnetic current comparator, made in the form of a transformer, the adjustable winding of which is connected to a direct current source, and

посто нна обмотка последовательно соединена с выходными зажимами и регулируемым источником тока, управл ег«2м детектором баланса ампер-витков 2.The constant winding is connected in series with the output terminals and an adjustable current source controlled by a 2m ampere-turn balance detector 2.

Недостатком данного устройства вл етс низка точность при воспроизведении малых токов вследствие магнитных шумов и дрейфа нул сердечликов магнитного компаратора тока.The disadvantage of this device is low accuracy when reproducing small currents due to magnetic noise and zero drift of magnetic current comparator cores.

Цель изобретени - повышение точности воспроизведени мгитых .токов.The purpose of the invention is to improve the accuracy of reproduction of fused. Currents.

Поставленна ; цепь достигаетс тем, что калибратор посто нного тока,содер-Delivered; The circuit is achieved by the fact that the DC calibrator, containing

5 жащий магнитный «омпаратор тока, состо щий из магнитного сердечника, регулируемой обмотки, включенной в цепь источника посто нного тока, и обмотки с посто нным количеством витков,5 a magnetic magnetic current imparator consisting of a magnetic core, an adjustable winding connected to the circuit of a direct current source, and a winding with a constant number of turns,

0 подключенной к регулируемому источнику тока, управл ющий вход которого соединен с детектором баланса ампервитков , снабжен первым резистором, включенным в цепь регулируемого источника тока, и вторам резистором,0 connected to an adjustable current source, the control input of which is connected to the ampere-turn balance detector, is equipped with a first resistor connected to the adjustable current source circuit and the second resistor,

Claims

connected to an additional regulated current source a, whose control input is connected to the input of a null indicator, while the cutters at one end are connected to adjustable sources, current and. to the inputs of the null indicator, and their opposite ends are connected to each other. The drawing shows a block diagram of the calibrator. The DC calibrator contains a magnetic current comparator 1, consisting of a magnetic core 2, an adjustable winding 3 and a winding 4 with a constant number of turns, a DC source 5, an ampere-turn balance detector 6, adjustable sources 7 and 8 current, fixed resistors 9 and 10, controlled zero-in. Indicator 11 and output: terminals 12 and 13 to which the load is connected. The device works as follows. A load is connected to output terminals 12 and 13. The calibrator is turned on and a direct current is passed through the adjustable winding 3 of Comprator 1 from the DC source 5, through the limbs of which the required current is set through the load. With the help of the detector, the balance of the amps of the revolutions is controlled by an adjustable current source 7, and thus the balance of the current amps of the magnetic current comparator 1 is automatically maintained. The voltage drops across the resistors 9 and 10 are compared using a null indicator 11, the output of which is controlled by the adjustable current source 8 and thus, the voltage drops on the resistors 9 and 10 are automatically maintained equal to any change in the number of turns of the adjustable winding 3 of the comparator 1 connected to the DC source 5 circuit At the balance of the ampere-turns of the magnetic current comparator 1, the equality iQWj or Ij - - --- I / where I and I, respectively, the current of the source 5 of the direct current and the regulated current source 7, is true; W and W ,, are, respectively, the number of included turns of adjustable winding 3 and the number of turns of winding 4 of comparator 1.. The voltage drops 0, Ua, respectively, of OTBSHHO on resistors 9 and 10 are automatically maintained equal to or 1,, g 1.1 ,, 2. - where R, and - are the resistances of resistors 9 and 10; Ij - current regulated source 8 current. Substituting equation 1 into 2, after simple transformations, we obtain 1,. -Wl .§:., I. Q The limiting relative error L of the proposed calibrator is equal to the insensitivity error of the zero indicator; the error ratio of the resistances of the constant resistors 9 and 10; absolute error due to magnetic noise and drift of the magnetic comparator. With a zero-indicator sensitivity of 0.1 µV and a value of the compared voltage drop equal to 1 V, the error due to the insensitivity of the null indicator is 10%. The inaccuracy i of reproducing small currents by the proposed device is determined only by the error of the ratio, the resistances of the resistors (it can be made equal to 5%). If the magnitude of the current of the direct current source is 10 mA and the maximum number of turns of the comparator adjustable winding is UNOO Then the error due to magnetic noise and drift. By introducing into the device two constant resistors, the equality of the voltage drops on which is maintained automatically by the controller, the error due to magnetic noise and the drift of the magnetic comparator is significantly reduced. DETAILED DESCRIPTION OF THE INVENTION DC Calibrator comprising a magnetic current comparator consisting of a magnetic core, an adjustable winding connected to a DC source circuit, and. windings with a constant number of turns connected to an adjustable current source, the control input of which is connected to an ampere turn balance detector characterized in that. That, in order to improve the accuracy of reproducing small currents, it is equipped with a first resistor connected to an adjustable current source and a second resistor connected to an additional adjustable current source, the control input of which is connected to the entered null indicator, with the resistors at their ends connected to adjustable current sources and to the inputs of the zero-indicator, and their opposite ends are interconnected.

Sources of information taken into account in the examination. Installation of potentiometric DC type U309. Technical description and operating instructions. Pp. 7-9, 1972.

2. The patent of France 1552315, cl. G 01 R 35/00 1966.

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