SU1285386A1 - Device for reproducing values of high d.c.currents - Google Patents

Abstract

The invention relates to electrical measuring equipment and is intended for use as a metrological equipment for the calibration of non-contact current meters in superconducting circuits. The aim of the invention is to expand the range of reproducible values of the current and improve the accuracy of the measurement of U nor. For this purpose, additional winding 12 of transformer 1, power source 13, and control unit 14 are introduced into the device. The drawing also shows a transformer 1 placed on a cryostat 2, the primary winding 3 of the transformer 1, the current source 4, the secondary winding 5 of the transformer 1, is made in the form of a thin ring of high current-carrying material, the heater 6 of the secondary winding of the transformer, source 7 power supply, Hall converter 8, current stabilizer 9, amplifier 10, digital voltmeter 11, Additional winding 12 performs the function of heating the primary winding 3 of the transformer. The location of the secondary winding ring 5 In the central part outside the solenoid of the winding 3, five to six times the utilization factor of the magnetic flux and allows to drive a large current into the ring with the same magnetic induction in the center of the winding 3. 3. Il. (Ls

Description

The invention relates to electrical measuring equipment, namely, devices using the effect of superconductivity, and is intended for use as a metrological equipment for the calibration of non-contact current meters in superconducting circuits.

The purpose of the invention is to expand the range of reproducible current values and improve the accuracy of their reproduction.

The drawing shows a block diagram of the device.

The device contains a transformer 1, placed in a cryostat 2. The primary winding 3 of the transformer 1, executed as a solenoid, is connected to the current source 4, and its secondary winding 5 is made as a thin ring of material with a high current-carrying capacity, and the height of the secondary winding ring

Block 14 can be implemented using switches or a set of relays with source-IC supply, which allow performing the specified operations with manual control.

The device works as follows.

} 0

At the operator's command, using the control unit 14, the power supply 7 and the secondary winding ring 5 of the transformer 1 are heated by the heater 6 and transferred to the normal (not 15 superconducting) state. Then, on the second command of the operator using the same control unit 14; Include the current source 4 and the output current of this source is linearly introduced into the primary winding 3 of transformer 1 to a predetermined value, while no current flows in the secondary winding 5. At the third command of the operator using

20

The control unit 14 placed outside the primary winding; 25 turns off the sources 3 of the transformer 1 in its central part by an order of magnitude less than the height of this winding 3. The device also contains the heater 6 of the secondary winding 5 of the transformer 1 connected to the power source 7, the converter 8 Hall, installed in the center of the ring of the secondary winding 5 of the transformer 1. Current electrodes transformer 4 current and current in the primary RBMOT-; ke 3 transformer 1 through | 10m of this source 4 is linearly output to zero. When the secondary winding 5 is in the superconducting state, the power supply 7 is disconnected, in which, at a high current, the EMF is induced from the primary winding 3, under the action of which in the secondary circuit ring

Block 14 can be implemented using switches or a set of relays with source-IC supply, which allow performing the specified operations with manual control.

The device works as follows.

At the operator's command, using the control unit 14, the power supply 7 and the secondary winding 5 of the transformer 1 are turned on by heating. 6 is transferred to the normal (non-superconducting) state. Then, by the second operator command, using the same control unit 14, the current source 4 is switched on and the output current of this source is linearly introduced into the primary winding 3 of transformer 1 to a predetermined value, while no current flows in the secondary winding 5. At the third command of the operator using

unit 14 controls turn off the source

The nickname 4 of the current and the current in the primary terminal 3 of transformer 1 through the | 10m of this source 4 are linearly output to zero. When the secondary winding 5 is in the superconducting state, the power supply 7 is disconnected, in which, at a high current, the EMF is induced from the primary winding 3, under the action of which in the secondary circuit

| Hall 8 bodies are connected to a stabilized coil 5, a current 1 of the current magnetiser 9 is flowing, and a hall through an amplifier 10 is connected to the input of a measuring device, such as a digital voltmeter 11, is wound with a primary winding made of copper The additional winding 12 connected to the power source 13, acting as the primary winding 3 driver. The inputs of the current source 4, the power source 7 and the power source 13 are connected to the outputs of the control unit 14, with which control of these sources, the control unit 14 at the command of the operator performs the operations of turning on and off the power supply 7 of the heater 6 of the secondary winding 5 of the transformer 1, turning on and off the linear sweep generator of the current source 4, turning the power supply 13 on and off of the additional winding 12 of the transformer 1 .

40

45

This flow compensates for the change in the magnetic flux created by the primary winding 3. Since the ring of the secondary winding 5 does not have a spa, i.e. spa resistance rj. 0, then the current in this winding will circulate as long as its superconducting state exists. When current flows in the secondary winding ring 5, Hall voltages of Hall converter 8 arrive at the input of amplifier 10, equal to

50

and.

where in

(at

SEC

cn

THX)

(ABOUT

SP to

55

magnetic induction associated with the flow of current in the ring of the secondary winding 5;

magnetic induction coupled to the magnetization of the secondary ring 5;

0

five

This flow compensates for a change in the magnetic flux created by the primary winding 3. Since the secondary winding ring 5 does not have a spa, i.e. spa resistance rj. 0, the current in this winding will circulate as long as its superconducting state exists. When current flows in the secondary winding ring 5, the Hall 8 ejectors of the Hall converter 8 are fed to the input of the amplifier 10.

and.

(at

SEC

cn

THX)

(ABOUT

where in

SP to

five

magnetic induction associated with the flow of current in the ring of the secondary winding 5;

magnetic induction coupled to the magnetization of the secondary ring 5;

and. THX

 at ,. „- magnetic induction associated with the magnetization of the solenoid of the primary winding 3;

control current of the Hall Converter 8; magnetic sensitivity converter 8 Hall. Then, at the operator's command, using the control unit 14, the power supply 13 of the additional winding 12 is switched on and the primary winding 3 is transferred to the normal (non-superconducting) state, and the magnetization of the solenoid of the primary winding 3 disappears, i.e. V. „p 0. At the same time, expression (1) transforms to the following form;

to

and.

fi

(AX

n.spk

).

(2)

and the output voltage of the amplifier is defined as

ten

and

out

 SEC

n

where k

but

yl, Ku (V

usi20 gain factor

25

letter 10.

Taking into account the small mass of the ring of the secondary winding 5, in expression (2) a member of Вц.п, (in comparison with a member

AT

SEC

can be neglected, then the expression (2) will have the form

J- -x a tnK cnK

and

out

Y x avslk

where is the magnetic constant of the secondary winding ring 5. Therefore,

SEC

So

I) iKyK (, p

 “..:

where fUo is magnetic constant;

SEC

that

SEC

SEC

the height of the ring of the secondary winding 5;

the radius of the ring of the secondary winding 5,

y blS-J tOft. Ix Kyiu,

+ 4Rc

Expression (3) shows that

current I

SEC

can be played with

high accuracy (on the order of 0.5-1%).

12853864

Performing the secondary winding 5 of transformer 1 in the form of a thin ring of a strictly defined height without a spa made of a material with a high current-carrying capacity makes it possible to obtain a continuous current of large magnitude in it, while the constant crcc of the secondary winding 5 can be determined with high accuracy reduce the current error.

The arrangement of the ring of the secondary winding 5 in the central part outside the solenoid of the primary winding 3 makes it possible to increase the utilization factor of the magnetic flux generated by the solenoid of the primary winding 5 to 5-6 times and thereby bring more current X into the ring with the same magnetic induction in the center of the solenoid the primary winding 3, since in this case the ring is placed in an area with a virtually zero magnetic field, which also allows a larger current to be brought into it.

Using the mode of current output from the solenoid of the primary winding 3 to zero to introduce current into the ring eliminates the effect on it and the Hall transducer 8 of strong magnetic fields created by the solenoid of the primary winding 3, which allows not only to bring more current into the ring, but also to leave of

35 areas of strong magnetic fields, in which the effect of quantum oscillations is observed in Hall converters and, therefore, caNEbiM improve the accuracy of measurements of reproducible currents.

40

The use of an additional winding wound by a copper wire together with the primary winding 3, forming a solenoid, effectively eliminates the contribution of the magnetization of the primary winding 3, transforming it along its entire length from the superconducting state to the normal heating of the additional winding,

50 and eliminate its effect on the Hall Converter 8, thereby increasing the accuracy of current reproduction. / 3) Location in the central part

outside the primary solenoid

55 3 rings of the secondary winding 5, having a height that is by an order of magnitude smaller than the height of this winding, allow the used ring to be placed in the region of the most uniform magnetic field.

current, which ensures that the ring receives the same current density (at its height), which in turn enhances the reproducibility of current over time.

Claims (1)

Formula and goiter shade A device for reproducing the values of high direct currents, containing a transformer placed in a cryostat, the primary winding of which is made in the form of a solenoid, is connected to a current source, and the secondary is made in the form of a thin ring of high current-carrying material, in the center of which is a Hall converter , the current electrodes of which are connected to the current stabilizer, and the Hall electrodes are connected through an amplifier; with the input of the measuring device, and the heater of the transformer secondary winding connected to the power source, characterized by the fact that 5, with a circuit extending the range of reproducible current values and increasing the accuracy of their reproduction, the transformer is equipped with an additional winding wound 0 together with its primary winding, an additional winding power supply and a control unit whose outputs are connected to the indicated current source, a power supply of the additional winding of the secondary winding respectively, the secondary winding of the transformer is placed outside its primary winding is in its central part, and the height of the secondary winding ring is an order of magnitude smaller than the height of the specified primary winding.