SU122207A1 - Device for synchronizing the switching on of the high voltage source when testing high voltage circuit breakers - Google Patents

Description

When using synthetic circuits for testing breakers for breaking capacity, the timing of switching on the high voltage source is of particular importance.

The proposed device for synchronizing the switching on of an overvoltage source during the testing of high-voltage circuit breakers is of a known type of devices of the same purpose, which CONCENT from a source of control voltage, a decisive and triggering node.

In known devices, active and inductive shunts are used as a source of control voltage, which reduce the noise immunity of the device and thereby reduce the reliability of its operation.

In order to eliminate this drawback, an air transformer is used as a source of control voltage, and the decisive node that serves to transform (integrate and differentiate) the control voltage is an electrical circuit consisting of combinations of active, and} 1 inductive and capacitive resistances.

FIG. Figures 1 and 2 show schematic diagrams of two embodiments of the device proposed in the device. The input control voltage is a voltage proportional to the derivative of the disconnected current supplied through the air transformer Tr.

The voltage from the transformer Tr, proportional to the derivative of the current (see Fig. 1), is supplied to the decision node, which is an integrating chain consisting of active resistances Ri and R2 and capacitor C. The voltage appearing on the capacitor C, 122207

is proportional to the current, and the voltage drop across the resistance is proportional to the derivative of the current.

A voltage is applied to the input of the starting relay node P

(((one)

where D is the proportional coefficient, and

If we assume that during a short period of time, the current curve can be approximated with sufficient accuracy by the MYWS - const, then the voltage reaches zero for seconds before the current zero passes the curve. Indeed, if U „„ 0 at the moment when. that

. . di ..

(3)

At a constant rate of change, the current reaches zero in time

D -1- -

Associated this expression With expression (3) it is easy to see that

The advance adjustment in the circuit of FIG. 1 is carried out by resistance - potentiometer Rz. In those cases when the current curve during the interval of seconds seconds cannot be sufficiently approximated by a straight line, the scheme (see Fig. 1) can be developed in the direction of taking into account higher order derivatives (see Fig. 2). The introduction of inductance in the form of an additional air transformer M ensures that the input voltage of the zero relay P is U „,„ proportional to the sum.

 2 dt - It can be said that this sum vanishes in seconds before the current curve passes through zero (assuming that the law of current variation during this time interval is expressed by a second-order polynomial).

To test the switches with the duration of current flow in several Half-Periods, a blocking element was introduced into the triggering node, which allows receiving output pulses not near each current, but only near a given current value.

Subject invention

A device for synchronizing the switching on of a high-voltage source when testing high-voltage circuit breakers, consisting of a source of control voltage, decisive and triggering KNOTS, characterized in that, in order to increase the reliability of its pa6otbi, an air transformer is used as a control voltage source and the decisive node, which is used to transform {integrate and differentiate) the control voltage, is made in the form of an electric chain consisting of an active, inductive and capacitive circuit. resisting.

/ di

. HS (2)

di sec

(ti,