SU1221620A1 - Method of inspecting inner windings of power transformers - Google Patents

Abstract

The invention relates to electrical measuring equipment and can be used in devices that provide on-line monitoring of the state of the windings of powerful power transformers without disconnecting them from the network. The purpose of the invention is to ensure the continuity of control of the internal windings. The device implementing the method contains the first 1 and second Z voltage transformers, clamps 3 and 4 for connecting the windings of the monitored transformer 5, the current transformer 6 and the intermediate transformers 7 and 8. Voltmeter 9 shows the difference between the pre-normalized voltage vectors of the transformer windings. The magnitude of the short-circuit resistance is defined as the product of the ratios of the difference between the vector voltages of the windings and the magnitude of the current and the measured frequency to the reference one. I il. O go go o) tsD

Description

The invention relates to electrical measuring equipment and can be used in devices that provide operational control over the state of the windings of powerful power transformers without disconnecting them from the network.

The purpose of the invention is to ensure the continuity of control of the internal windings of a power transformer without disconnecting it from the network.

The drawing shows the fuctional scheme of the device variant that implements the proposed method.

The device contains the first 1 and second 2 voltage transformers, clamps 3 and 4 for connecting the primary and secondary windings of the monitored power transformer 5, the current transformer 6, the first 7 and second 8 intermediate transformers, voltmeter 9, ammeter 10 and frequency meter 11, and terminals 3 and A for connecting the primary and secondary windings of the monitored power transformer 5 are connected to the primary windings of the first 1 and second 2 voltage transformers, respectively, the secondary windings of which are connected to the primary volt The first 7 and second 8 intermediate transformers, the secondary windings of which are connected in series with each other and in series with the voltmeter 9, have a current transformer 6 on the secondary side of the monitored power transformer 5, in parallel with which ammeter 10 is connected, parallel to terminals 4 for connecting the secondary winding controlled power transformer 5 connected frequency meter 11

The device works as follows.

To determine the presence and degree of deformation of one of the internal windings of the power transformer 5, it is first necessary to connect the first and second transformers 1 and 2 of the voltage to the test object. Then on the secondary side of the power transformer 5 install the current transformer 6. After that, the tap changer of the power transformer 5 and, therefore, the nominal voltages of its primary and secondary sides are set to the position corresponding to the power control stage under consideration.

transformer 5. The transformation ratio of intermediate transformers 7 and 8 is chosen so that the condition is fulfilled

Lg

KT

one

where and, and are the nominal values of the voltages of the primary and secondary windings at the stage of control, respectively;

K and K-j. - the resulting transformation ratios of the first transformer, 1 voltage and the first intermediate transformer 7, the second transformer 2 voltage and the second intermediate transformer 8.

After the device is assembled and the controlled transformer is connected to the mains, voltmeter 9 shows the difference of the vectors of normalized voltages of the primary and secondary windings. The difference thus measured is divided by the value of the current of the total ammeter 10. The resulting

Z value

 specified by the formula

7 ii3: JM

To "iM f

 and

where Z, is the true value of the short circuit resistance;

HjM frequency measured by frequency meter II;

f C - the nominal frequency of the network.

Thus, the proposed method allows monitoring the state of the windings of power transformers without disconnecting them from the network, which increases the uninterrupted power supply of consumers of electrical energy.

Claims (1)

Invention Formula The method of controlling the internal windings of power transformers, which consists in determining the actual value of the short-circuit resistance of the internal windings of the power transformer, is compared 3.12216204 This value, with the reference, by the power transformer's resolution, the resolution of a certain value over this factor, is divided by the ratio of the difference normalized to the degree of deformation vectors of primary voltages controlled windings, about tl and - and secondary windings to the value is that, with the purpose of the 5th current, the voltage frequency of the continuity of control of the power transformer is measured, the internal windings of the transformer are found, the ratio of the measured value of They measure the primary and secondary internal windings for the resistance of a short-circuit power transformer, normalized to fO. nor as a product of ratios times (the difference between the normalized vectors of the winding voltage vectors and of the voltages of these windings, due to the magnitude of the current and the measured frequency measure the current value of the secondary about the reference.