SU690413A1 - Device for measuring error deviations of current transformers in transient modes - Google Patents

Description

one

The invention relates to the field of electrical measuring equipment and can be used to determine deviations of current transformer errors in transient conditions from normalized values at manufacturing plants or test centers. Devices are known that allow the investigation of the potential of current transformers in transients 1. The current transformers are tested by switching on its primary winding through a linear inductance at a given phase of an alternating current source. However, the registration of the operation of current transformers in this case is performed on photosensitive material, or by memory devices.

The closest in technical essence to the invention is a device for measuring deviations of errors of current transformers in transient modes, containing a working frequency current driver, the output of which is connected to the transformer under test connected in series with the primary winding and measuring transformer in the secondary winding of the transformer. an ammeter, and in series the secondary winding of the transformer under study are connected in series the first load, second ammeter and direct current source 2.

A disadvantage of the known device is the low accuracy of measurement.

The purpose of the invention is to improve the measurement accuracy.

This goal is achieved by the fact that in a known device for measuring

5 deviations of errors of current transformers in transient modes, containing a current frequency driver operating frequency, the output of which is connected with the primary winding of the transformer under investigation and the primary winding of the measuring transformer, in series, the first ammeter is connected to the secondary winding, and the secondary

The 5 windings of the transformer under study included the first connected load, the second ampere-Etr and the DC source, the basic transformer was introduced, the third

and the fourth ammeters and the second on tpyaika, with the third ampere p

connected in series with the power supply current, and parallel to this. / circuit includes a fourth ammeter connected in series, the second load and the secondary winding of the basic transformer, the primary of which is connected in series with the primary winding of the transformer under study. ten

The drawing shows the principle. A diagram of a device for measuring the deviation of errors of current transformers in transient conditions;

. The device contains a current operating frequency generator 1, a measuring transformer 1ator 2, a transformer under study 3, a basic transformer 4, the first and second load „

5, 6 ammeters 7, 8, 9, 10, DC source 11.

The deviations of the current transformer errors are measured in the following order: a constant ampere 9 from a source 25 in the secondary winding of the base transformer 4 establishes a constant current, the value of which is determined by calculating the aperiodic magnetizing current for the base transformer 4 of the transformer 4 at a given load the primary em and current of its damping time. The magnitude of the total error of the basic transformer 4 must “be known in advance. 35, due to the fact that the performance of the basic 4 and the investigated 3 transformers is similar, the resistance is; stshshnu current their secondary circuits

will be the same, therefore, the P Q indices of the ammeters 9 and 8 will be the same. . , . . .. -. o -.-,., ......., ---, -., .. and. „,,

When switching on the generator of a periodic current operating frequency of 1 on the yo: luminous circuits of both TTOlibB trans- bearing to the base transformer

py 4. .... / -....,. : ./,: ..; ...

The inclusion of the amperers 8 and S into the secondary circuits of their transformers allows not only to measure the values of direct currents in the circuits, but also to counter the directions of the disconnection. The error of the transformer under study is 60 in the transitional resiuTGyu to that: or other direction according to the norm5rpay ei-o value, the relative value of the deviations

power transformer current transformer in 5

mode is determined from

I.

r ooi:%

where is the absolute value of the error deviation measured by ammeter 10; I - the value of the primary current

measured by ammeter 7. DC source 11 should be used as a source of direct current, which allows one to pass a periodic current and have a small resistance to the transmission of this current.

the use of a direct current source in conjunction with. Ammeters common to the secondary circuits of both transformers make it possible to directly measure the deviations of the current transformer errors in the transient bursts from the normalized or basic values with high accuracy over a wide range of variations in loads, wake currents and constant times of their decay. The use of this device for measuring deviations in operation is more efficient compared to isolating THbiMH, since the proposed system does not require the use of a demagnetizing circuit containing a DC source, inductance and a variable resistor,

Claims (2)

1. USSR author's certificate No. 390478, cl. Q01 R 31/02, 1973. 2. USSR author's certificate 552571, class, G01 -R 31/02, 1977 (prototype).