SU140904A1 - Method for measuring contact resistance of oil circuit breakers - Google Patents

Description

The present invention relates to methods for measuring contact resistances of oil circuit breakers.

The proposed method differs from the known ones in that pulses create damped oscillations in an oscillating circuit consisting of a current-carrying circuit of the switch phase and a capacitor connected to its terminals, and the average value of the rectified capacitance voltage proportional to the magnitude of the transition resistance is measured.

The use of this method simplifies the apparatus for measuring transient resistances at high currents and voltages.

The proposed method is also distinguished by the fact that, in order to more accurately measure the magnitude of the transient resistance, the voltage taken from the capacitance of the oscillating circuit is compared in a compensation circuit with the reference voltage obtained in the relaxation circuit.

The drawing shows a diagram of an instrument for carrying out the proposed method.

The capacitance Ci through the thyratron T, whose grid is controlled by the voltage of the industrial frequency LJg, is discharged to a capacitor Co with a constant time

- -. and so t. h- 4,

1 g

Ui, Uo

where Go is the period of the natural frequency of the circuit.

With an appropriate choice of Cz and Rz, as well as observing1R1

Research Institute of conditions 7-t (T-period of industrial frequency), W / 1)

№1409042 resistance voltage will be equal to

  r b jl 0

., "

where 0

(ds about -

This is for example | enI | Yves are measured according to a compensation scheme that works as follows. Capacitance C through the thyratron TZ, controlled by the voltage U, z, is discharged into resistance with a constant time T2, and T2; -r- When it is discharged at resistance R

average voltage will be equal to

and 2 Ui-C-2o „t-. D (4 - - rr, j, - Lg AI,

U.C,

., l.

where is A2 const.

By changing the resistance value with the slider position of the potentiometer, you can compensate for the f / s value. In this case, the device IP will show "O. With compensation

6 - (Y, and ..., from here 4 --4AOL2 A 4

and since RU is RK where. is the resistance of the contact, and is the resistance of the supply wires,

/ Cr, 1

1 - Р

When C2 -

The value / „match51 and depends on the selected connecting wires.

The scale of the potentiometer can be calibrated in magnitude. The device can serve as a null indicator and showing with a direct reading of RK on the scale.

Subject invention

Claims (2)

1. A method of measuring transient resistances of contacts of an oil circuit breaker, characterized in that, in order to simplify apparatus for measuring transient resistances at high currents and voltages, pulses create damped oscillations in an oscillatory circuit consisting of a current-carrying circuit of the circuit breaker and capacitor connected to its leads, and the average value of the rectified voltage of the capacitance, proportional to the magnitude of the transient resistance, is measured. 2. The method according to claim 1, in connection with the fact that, in order to more accurately measure the magnitude of the transient resistance, the voltage taken from the capacitance of the oscillating circuit is compared according to a compensation circuit with reference voltages lm obtained in the relaxation scheme. Cemi