SU1210176A1 - Device for protection of capacitor leads of electric devices against damage - Google Patents

Description

{1210176

The invention relates to electrical engineering, namely, to the relay protection of electrical systems of alternating tone.

ka, and is intended to protect the capacitor inputs. electrical apparatus.

The purpose of the invention is to increase the sensitivity and reliability in operation.

The drawing shows a block diagram of the proposed device.

The device contains the body of the zero-sequence current with two outputs, differentiating element

2, phase relay electoral authorities 3 ,, the first three logical AND 4, the logical element I.PI 5, the fourth logical element And 6, the inverter 7 logical signals, the fifth logical element And 8.

The inputs of the relay measuring element 1 of the zero-sequence current with two outputs are connected to the current circuits of all three phases of the protected capacitor inputs, and its summing input is connected via a differentiating element 2 to the source of the zero-sequence voltage. The current circuits of all three phases are also connected to the inputs of each of the three electoral agencies.

3, reacting to the modulation of the current module of one phase above the module of the geometric sum of the currents of two OTHERS 11X phases, the summing input of each phase electoral authority 3 is connected to the output of differentiating element 2, and the output of each phase electoral authority is connected

with one input of the logic element 4, the second input of which is connected to the first input of the measuring body 1 of the zero-sequence current, and the outputs of the elements 4 and 4 are outputs of the device acting on the signaling.

The inputs of the logical element OR 5 are connected to the outputs of the phase relay electoral bodies 3, and its output, connected according to the AND 6 scheme, to the second output of the relay measuring body 1 of the zero-sequence current,. is the output of the device, acting upon the disconnection of the electrical apparatus. The inputs of the logic element And 8 are connected to the outputs of the relay measuring body 1 current zero follower. with the first output connected

five

directly, and the second - without the inverter 7, the output of the element And 8 is connected to the input of switching the sensitivity of each phase electoral authority.

The device works as follows.

At the initial stage of damage to the capacitor input, a breakdown occurs between the individual layers of capacitor insulation, the equivalent input capacitance to earth increases and the component of the fundamental frequency of the capacitive current of the faulty input increases. The zero sequence current filter, which is part of the zero sequence relay unit 1, increases the capacitance Q of the input current, and when it reaches the threshold value corresponding to the setpoint, at the outputs of the relay zero level current circuit, 5 signal, and the sensitivity of the organ on the first output is higher than on the second,

Preventing (false positives of the device under the action of the components of the zero sequence of the capacitive current of the inputs during the ground circuit in the primary network or in the case of non-full-phase modes is performed by compensating for the unbalance in such modes with a current proportional to the zero-sequence voltage of 3Uo. Necessary The compensating value with respect to the voltage of 3 Uo at 90 ° in the direction of the advance, simulating the capacitive nature of the unbalance current, is produced by means of a differentiating element. 2. In In the event of a developing damage to the input compensation, the zero sequence component does not occur and the response of the zero sequence relay body occurs with a sensitivity threshold independent of the presence of the zero sequence component in the primary network.

The diagrams of the phase relay electoral bodies 3 allow one to obtain a phase output of the device with an action on an alarm and, moreover, prevent the false triggering of the entire device when one of the fa is broken; capacitive current circuits, because the specified mode occurs.

0

five

0

five

0

3

the false action of the zero-sequence current measuring device. Since the outputs of the device with the action on the shut-off and on the alarm are enabled according to the schemes A and A and 6 with the outputs of the faders of the electoral authorities, the false action of the device does not occur.

The action of the phase relay electoral authorities is based on the comparison of the modular capacitive current of each of the inputs with the module of the geometric sum of capacitive currents in the other two phases and a value proportional to the voltage of the zero sequence 3Uo in the primary network. The latter value is taken from the output of the differentiating element 2 and is fed to the summing input of the phase electoral authority. At the same time, its necessary phase shift with respect to the 3Uo voltage of the primary network is ensured.

In the absence of tripping of the zero-sequence current organ, both outputs at the output of the logic element And 8 have a signal O and the sensitivity of the phase electoral authorities 3 is low.

With an increase in the current of one of the inputs in the course of damage development, a signal appears at the first output of the zero sequence current organ 1, which leads to the appearance of signal 1 at the output of element I 8, since at its second input there is signal 1 from the output of inverter 7. The sensitivity of the phase electoral authorities 3 at the same time becomes higher than the sensitivity of the organ of the zero-sequence current, and the appearance of signals at the outputs of the elements AND 4 defined / ti4

It is only the sensitivity of the zero-sequence current organ on the first output.

With further increase in current

A damaged input appears at the second output of the zero sequence current organ 1. At the output of elements 7 and 8, signals O appear, and the sensitivity of the phase

of the electoral authorities becomes lower, but the sensitivity of the zero current organ 1 on the second output is lower. Therefore, the device action to disable

occurs with the sensitivity determined by the sensitivity of the organ 1 of the zero-sequence current on the second output.

In the event of a phase failure capacitive

current is triggered by the zero-order current organ at both outputs, but the sensitivity of the phase organs will be low, which improves the detuning from the unbalances arising in this mode at the output of the comparison circuit of the absolute values of electrical quantities determined by the change in the phase ratios of the compared values and the error of the adders.

Thus, the switching of the sensitivity of the phase measuring organs, depending on the state of the signals at both outputs of the organ

zero sequence current allows to resolve the contradiction between the need to have a high sensitivity to the output on the alarm and the detuning from the unbalance,

arising at the output of the comparison circuit at the break of one of the phases of the capacitive current.

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Phase A

Phase B

Fa for C

Compiler L.Vaskova Editor V.Petrash Tehred Z.Kastelevich Proofreader S.Shekmar

Order 527/57 Edition 613 Subscription

VNIIPI USSR State Committee for Inventions and Discoveries. 113035, Moscow, Zh-35, Raushsk nab. 4/5

Branch gash Patent, Uzhgorod, st. Project, 4

Claims (2)

1. DEVICE FOR PROTECTING CAPACITOR INPUTS OF ELECTRICAL EQUIPMENT AGAINST DAMAGE, containing a zero sequence current element connected to capacitor inputs with a summing element at the input, the first output of the zero sequence current element connected to the first inputs of three AND elements, the second inputs of which are connected to the outputs of the corresponding selective phases organs with summing elements at the input, the inputs of the selective phase organs are connected to the capacitor inputs, the outputs of the elements And are connected to the corresponding To the existing signaling organs, the outputs of the selective phase organs are also connected through the OR element to the first input of the fourth AND element, the second input of which is connected to the second output of the zero-sequence current organ, the additional input of the zero-sequence current organ summing element is connected to the zero-sequence voltage source via a differentiating element , while the output of the fourth element And is connected to a disconnecting organ, which is related to the fact that, in order to increase feelings telnosti, the output of the differentiating element is connected to the auxiliary inputs of summing elements polling phase bodies. 2. The device according to claim 1, characterized in that, in order to increase reliability in operation, the selective phase organs are configured to change the sensitivity, and the first output of the zero-sequence current organ is connected through the newly introduced fifth element And to the additional inputs of the sensitivity change of the selective phase organs, while the second input of the fifth element And through the newly introduced inverter is connected to the second output of the zero-sequence current organ. . SU., „1210176 ί 12