RU2163382C1 - Device recording commutation wear of switches - Google Patents

Abstract

FIELD: electrical engineering, high-voltage oil-immersed switches of electrical networks in particular. SUBSTANCE: invention is aimed for elongation of overhaul periods of switches. It is achieved by insertion of diode-resistor converter to calculate power function of short-circuit current. Device has transreactor 3 connected with primary winding to current transformer 2 controlling current of high-voltage oil- immersed switch 1, rectifier 10 whose input is connected through adjustment resistor 4 to secondary winding of transreactor, pulse generator 38-47 connected through coincidence circuit based on elements 30-32, 34-37 to pulse counter 33, storage capacitor 21 connected by make contact 20 of output of fault relay and by break contact 22 of fault relay through linearization converter assembled on compound transistor 23 and elements 24-28 to emitter-base junction of input transistor 30 of coincidence circuit. Voltage divider based on resistors 9, 19 is connected in parallel to output of rectifier. Four diode-resistor networks 5-18 are placed in parallel to one of them, anodes of all diodes are linked to output of rectifier and common point of resistor of voltage divider is connected to input of make contact of fault relay. All cathodes of diodes of diode-resistor networks are connected through additional resistor to stabilizing voltage. EFFECT: prolonged overhaul periods of switches. 1 dwg

Description

 The invention relates to electrical engineering, in particular to high-voltage oil circuit breakers.

 Known devices for fixing the values of short-circuit currents in electric networks and evaluating the switching wear of oil switches [1, 2], containing a transreactor, a rectifier, a storage capacitor, a linearizing converter, a pulse generator connected through a matching circuit with a pulse counter.

(*)
где I - отключаемый ток масляного выключателя MB;
I_ОНОМ - ток, для которого нормируется допустимое количество операций отключения MB;
n_I, n_o - соответственно число операций отключения при токах I и I_ОНОМ;
γ - коэффициент, находящийся для различных MB в пределах 1,2-2,5, этот коэффициент определяет интенсивность износа MB.The disadvantage of these devices is that they do not allow to evaluate the real switching wear (CI) of the oil switch. In accordance with new studies carried out in the LPO "Electroapparat" and the Research Center for High-Voltage Equipment (SIC VVA), the dependence of the KI on the values of short-circuit currents is determined by the relation [3] :)

(*)
where I is the disconnected current of the MB oil switch;
I _ONOM - current for which the permissible number of shutdown operations MB is normalized;
n _I , n _o - respectively, the number of shutdown operations at currents I and I _ONOM ;
γ - coefficient, which is for various MB in the range of 1.2-2.5, this coefficient determines the wear rate of MB.

As can be seen, the intensity of the IC depends on the switched-off current to the power of γ. At the same time, devices [1, 2] do not take into account this power-law dependence, which leads to a large error in the assessment of switching wear of circuit breakers and a decrease in their overhaul life
The aim of the present invention is to increase the turnaround time of circuit breakers.

 This goal is achieved by the fact that in the device for fixing the switching wear of the oil switch, containing a transrector connected by the primary winding to a current transformer that controls the current of the high-voltage oil switch, a rectifier, the input of which is connected via an adjustment resistor to the secondary winding of the transreactor, a pulse generator connected via a circuit coincidence with the pulse counter, a storage capacitor connected to the output of the make contact of the damage relay, and the disconnect the contact of the damage relay is connected through a linearizing converter assembled on a composite transistor to the emitter-base of the input transistor of the matching circuit connected to the rectifier output is a voltage divider across resistors, one of which connected to the positive output of the rectifier has four diode-resistor circuits connected in parallel, moreover, the anodes of all diodes are connected to the positive terminal of the rectifier, and the common point of the resistors of the voltage divider is connected to the input of the NO contact of the relay Wait, all the cathodes of the diodes of the diode-resistor circuits are connected to the stabilizing voltage through additional resistors.

 Such an embodiment of the device, in which a voltage divider across resistors is connected parallel to the output of the rectifier, one of which is connected to the positive output of the rectifier, four diode-resistor chains are connected in parallel, the anodes of all diodes connected to the positive output of the rectifier, and the common point of the resistors of the voltage divider connected to the input of the closing contact of the damage relay, all the cathodes of the diodes of the diode-resistor chains through additional resistors connected to the stabilizing voltage allows vysit accuracy fixation switching switch wear and increase their turnaround time.

 Schematic diagram of the device shown in the drawing.

 The device comprises a transreactor 3 connected by a primary winding to a current transformer 2, which controls the current of the high-voltage oil switch 1; a rectifier 10, the input of which is connected through an adjustment resistor 4 to the secondary winding of the transreactor; a pulse generator 38-47 connected via a matching circuit assembled on elements 30-32, 34-37 with a pulse counter 33; a storage capacitor 21, which is connected to the output of the make contact of the damage relay 20, and the disconnect contact of the damage relay 22 is connected through a linearizing converter assembled on a composite transistor 23 and elements 24-28, to the emitter-base of the input transistor 30 matching circuit; parallel to the rectifier output, a voltage divider is connected across the resistors 9, 19, to one of which connected to the rectifier’s positive terminal, four diode-resistor chains 5-18 are connected in parallel, the anodes of all diodes connected to the rectifier’s plus terminal, and the common point of the voltage divider resistors connected to the input of the make contact of the fault relay; All the cathodes of the diodes of the diode-resistor chains are connected to the stabilizing voltage through additional resistors.

 The device operates as follows.

 In the normal state, the transistor 34 is closed and the signal from the output of the pulse generator does not pass to the pulse counter 33.

When short circuit in the electric network through the output contacts 48 of the relay 50 is activated and its contact 20 connects the capacitor 21 through the divider 9, 19 to the voltage of the rectifier 10, proportional to the short circuit current. The backup voltage U ₅ - U ₈ on each diode of the diode-resistor chains depends on the resistance values of the divider 11, 12 ... 17, 18 and the value of the reference voltage U _ST . As long as the voltage of the rectifier is less than any supply voltage, the current passes only through resistor 9. If the voltage increases, then after it becomes more than U ₅ , the diode 5 is unlocked and resistor 12 is connected in parallel with resistor 9. As the voltage increases by the second diode opens, the third and so on. The reference voltage at the diodes and the resistance values of the divider are selected so as to ensure the dependence of the output voltage on the resistor 19
U ₁₉ = k $\genfrac{}{}{0ex}{}{\text{γ}}{\text{1}}$ ₀ .
Thus, the capacitor 21 is charged to a voltage proportional to I ^γ .
When the short circuit is disconnected, the relay 50 is de-energized and the capacitor 21 is discharged through the terminal 22 of the relay 50 and the converter 23. The voltage on the capacitor decreases linearly, since it is discharged with a constant current value. The discharge current locks the transistor 30, as a result of which the output signal of the pulse generator passes to the transistor 34 and controls the pulse counter 33.

 When the capacitor 21 is completely discharged, the transistor 30 opens and locks the transistor 34, thereby stopping the pulse counting of the generator. Therefore, the time interval for the discharge of the capacitor is converted into the number of pulses proportional to the switching wear of the circuit breaker.

 The technical and economic efficiency of the invention lies in the fact that it allows you to take into account the decrease in KI when you turn off the MB low short circuit currents. Using a simple example, we show the effectiveness of the new standardization method.

По новому методу нормирования при этих же условиях (принимая значение γ = 2) по формуле (*) определим

Таким образом допустимое число отключений MB повышается в 1,75 раза. Из предлагаемого примера также видно, что повышение точности фиксации коммутационного износа выключателей позволяет увеличить межремонтные сроки выключателей и, следовательно, уменьшить затраты на их эксплуатацию.Let I _ONOM = 3500A, n _o = 30, and the short-circuit breaking current I = 2000A. Then, according to existing standards of "total kiloamperes" [4], the number of current cuts I = 2000A will be

Using the new method of normalization under the same conditions (assuming the value γ = 2), using the formula (*)

Thus, the permissible number of MB outages is increased by 1.75 times. It can also be seen from the proposed example that increasing the accuracy of fixing the switching wear of circuit breakers can increase the turnaround times of circuit breakers and, therefore, reduce the cost of their operation.

Sources of information
1. A.S. USSR N 324584, MKI G 01 R 9/10. Device for fixing the values of short circuit currents. / Gatalsky G.I. - Discoveries. Inventions, 1972, N 2.

 2. Figurnov EP, Kurganov V.V. Device for predicting the life of oil switches 27.5 kV. - In the book: Operating modes, diagnostics and control of railway power supply devices. Interuniversity collection of scientific papers, vol. 153. Rostov-on-Don: RIIZHT, 1979, p. 3-5.

 3. Bobylkov AN, Vishnevsky Yu.I., Zagaykevich BD, Sherman Ya. N., Shleifman I. L. Switching wear resistance of high-voltage circuit breakers. - Electric stations, 1986, N 4, p. 62-64.

 4. Instructions for maintenance and repair of equipment for traction substations, power points and sectioning of electrified railways. CE / 39 06/30/92, M., Publishing house "Yuji", 1993. - 93с.

Claims (1)

 A device for fixing the switching wear of an oil circuit breaker, comprising a transreactor connected by a primary winding to a current transformer that controls the current of a high-voltage oil circuit breaker, a rectifier whose input is connected via an adjustment resistor to the secondary winding of a transreactor, a pulse generator connected through a matching circuit with a pulse counter, a storage capacitor connected to the output of the make contact of the fault relay, and the break contact of the fault relay is connected through a linearizing converter assembled on a composite transistor to the emitter-base input transistor of the matching circuit, characterized in that a voltage divider is connected to the rectifier output across the resistors, one of which connected to the rectifier's plus terminal has four diode-resistor circuits connected in parallel, and the anodes of all diodes are connected to the positive terminal of the rectifier, and the common point of the resistors of the voltage divider is connected to the input of the NO contact of the fault relay, all the cathodes of the diode rows of diode-resistor chains through additional resistors are connected to a voltage stabilizer.