SU1597805A1 - Method of testing switches for disconnection of capacitive currents - Google Patents

Abstract

The invention relates to electrical engineering and can be used to test high-voltage circuit breakers in the mode of disconnecting a capacitive load. The purpose of the invention is to increase the reliability of the tests by reproducing a given amplitude and phase of the highest harmonic current. In order to obtain a given higher harmonic component in the switchable current, the oscillating circuit is switched on with a delay in relation to the moment of connecting the switchable current circuit with the precharged switchable capacitor to the charged capacitor battery of the oscillating circuit. The lag time depends on the parameters of the main harmonic and the reproduced higher harmonics, as well as on the parameters of the test circuit. The description shows an example of a device implementing the method. 1 hp f-ly, 1 ill.

Description

The invention relates to electrical engineering, in particular to tests of high-voltage switches in the mode of disconnecting a capacitive load.

The purpose of the invention is to increase the reliability of tests by providing usable tests that are close to the mode of switching off the filter-compensating circuits.

-The drawing shows a diagram of the device that implements the proposed method.

The device contains an industrial-frequency oscillating circuit consisting of a series-connected capacitor battery 1, a switch-on element 2 and a reactor 3. Parallel to the oscillating circuit, a switch-off current circuit is connected, consisting of a series-connected capacitor 4, which reacts the inductance of the filter of the reactor 5, terminals 6 and 7 to connect the test switch, reproducing the inductance of the reactor network 8 and the separator 9. Parallel to the reactor 5 is connected a transient recovery control circuit A voltage filter side, consisting of series-connected resistors 10 and a capacitor 11. Parallel to the reactor 8, a control circuit for a transitional voltage-reducing side, consisting of a series-connected resistor 12 and a capacitor 13, is connected. In parallel with the separator 9, the contactor 14 and terminals 15 and G6 of the switch 17 of the source 18 of the charging voltage.

The sequence of operations offers svlyklyuchat. 1st

in my way of testing

Before the experience, the switching element 14, the contactor 14 is open, the terminals 6 are closed by the tested switch, the divider 9 is closed, and the contact of the switch 17 is closed to terminal 15 if the capacitor 4 should be charged to a higher voltage than capacitor battery I, or to terminal 16, if to more than vyssd

with

00

about sd

Whose voltage should be charged battery 1. After charging the capacitor battery 1 or capacitor 4 to a predetermined voltage, turn off the separator 9 and continue charging the remaining capacitors to a given high voltage, then the source 18 of the charging voltage is turned off. First, a command is issued to turn off the test switch, then turn on the contactor 14, provide a time delay equal to t, then turn on the switching-on element 2 of the oscillating circuit. At the same time, a capacitive current containing the first (main) harmonic and one higher harmonic flows through the switch under test, the phase and amplitude of which are determined by the delay time of switching on the oscillating circuit with respect to the moment of switching off the current to the capacitor battery.

With this sequence of operations, at the moment of switching on the oscillatory circuit t, a current flows through reactors 5 and 8

 smcDT, coL

where At / is the difference between the charging voltages of capacitor 4 and capacitor bank 1;

(ABOUT

T / r + c / cI

own frequency of current in

reactors after the closure of the circuit 14;

L and С are the values of inductance and capacitance of the switched-off current circuit (total inductance of reactors 5 and 8 and capacitance of capacitor 4); Co is the capacitor capacitance value.

battery 1.

The formation of a disconnected current due to the initial current in the reactors significantly increases the functionality of the circuit, since in this case it is possible to regulate not only the amplitude but also the phase of the highest harmonic of the current depending on the time delay t determined from the analytical decision for the disconnected current taking into account the value to at time t after exclusion

1 dCO - b) I s. P

  (V 6) /, cOS4 |) v

where V is the highest harmonic number;

/ V - amplitude ratio vth and first

current harmonics;

, - the initial phase of the current harmonic; a and b are coefficients depending on the frequency parameters of the circuit. Odds a and. B determined by the formulas

- b

too

. -0) f

with

Where

five

0

five

(Oy-0) 0

0) 1-frequency first harmonic frequency;

(Ov (oiv - the angular frequency of the higher harmonics;

(j) o / / LoCo is the natural frequency of the oscillating circuit; LO is the inductance of the oscillating circuit.

Thus, connecting a disconnected current circuit to the oscillating circuit charged with a capacitor battery before it is turned on and adjusting the time delay of the oscillating circuit switching-on time allows to reproduce the specified amplitude and phase of the highest harmonic in the current, which increases the reliability of the tests, ensuring testing of circuit breakers in the mode of filter-compensating devices .

Claims (2)

1. A method for testing switches for switching off capacitive currents, consisting That a capacitor battery of an oscillating circuit of an industrial frequency and a capacitor of a switched-off circuit is charged to a different voltage, a capacitor battery and a circuit of a disconnected current are connected parallel to the reactor of an oscillating circuit, and then the circuit breaker is disconnected, in order to increase the reliability of the tests, pre-connect the circuit of the disconnected current parallel to the capacitor battery, and .connection of the capacitor battery and the circuit of the disconnected current parallel to the reactor oscillatory circuit is performed with a time delay after which the test is carried out off switch. 0 2. The method according to claim 1, characterized in that the time delay is determined from the ratio (); УЬ) 1у5тУ.  G + C / Co 1 -vbI i + (- fe) / vcos4 |) v where t is the time delay value; L, С - inductance and capacitance values tripping circuit; Co-capacitance value batteries; a, b are coefficients depending on the frequency parameters of the circuit; V is the highest harmonic number; / V - amplitude ratio vth and first current harmonics; 1 | 5 - the initial phase of the current harmonic.