SU139369A1 - Device for measuring electric arc parameters - Google Patents

Description

Devices are known for measuring the parameters of an electric arc using a computing device that is automatically switched on for the duration of the arc.

The proposed device differs from the known ones in that it uses: an electronic driver for starting pulses, which is triggered by a voltage jump caused by the appearance of an arc. A ferromagnetic stopping pulse sensor, made in the form of an annular core with two windings, is also used. A single coil of the sensor flows through the arc current, and the other, magnetizing, serves to obtain a sharp pulse at the time of the arc redemption and the current drop abruptly to zero.

Such an embodiment of the device makes it possible to directly use the parameters of the controlled arc for controlling the switching on and off of said device. The use of the device allows a drastic reduction in the time for studying the arc of controlled contactors, relays, switches, etc., and also frees the operator from time-consuming calculations and subjective errors.

Pa figs. Figure 1 shows a circuit for applying voltage from a controlled arc and from a measuring shunt to a device; in fig. 2 is a block diagram of the device; in fig. 3 waveform of current and voltage of controlled arc.

By means of the device, the signal measured by the three switch instruments is proportional to the energy, the amount of electricity and the arc time.

Voltage U from the arc and voltage from the measuring shunt connected to the arc circuit (Fig. 1) are supplied to the multiplication block (Fig. 2), which forms a signal proportional to the arc power by implementing the ratio:

: No. 139369- 2-ui - (u + i) ™ - (u i) 2.

The received signal is fed to an energy integrator 2. The integrated power signal f uidt W is measured by a bridge circuit 3

with a switch device included in the diagonal, the scale of which is calibrated directly in joule x. Simultaneously with the ethyl voltage / shunt, proportional to the arc current, is fed to the integrator

the amount of electricity 4. The integrated signal f idt Q is measured by a bridge circuit 5.

The arc time measurement is done by integrating

a rectangular impulse equal in duration to the arc burning t j u const dt t.

The integration is performed by the integrator 6. The counting is carried out using a bridge device of the bridge circuit 7. To integrate only during the arc, the device has an integrator control circuit. The control circuit includes integrators at the time of arc ignition and stops integration at the moment of arc redemption.

The control scheme works as follows: the leading edge of the "a.v. arc voltage (fig. 3), corresponding to the moment of ignition, is formed in a short-term pulse by cascade of formation 8 (fig. 2). This impulse overthrows the triggers 9, 10, 11, which involve integrators in the work.

The moment of redemption of the arc, which burned time t, is characterized by a sharp cessation of current in the section c, d (Fig. 3). This current jump is converted by cascade 12 (Fig. 2) into a short-term pulse acting on the triggers. The triggers return to their original position, terminating the integration process.

The values obtained as a result of integration are stored in the memory of the instrument for the time required for reference. After the measurement process is completed, the integrators are returned to the initial state by the reset button. To check the accuracy of operation, the device is equipped with a control circuit 13.

Subject invention

A device for measuring the parameters of an electric arc, namely: the time of its burning, the energy released on it and the amount of electricity flowing through Fiee, with the help of a computing device that is automatically switched on for the time of burning of the arc, in order to directly use the parameters of the arc for control on and off the device, applied electronic driver, triggered by a voltage surge caused by the appearance of the arc, and a ferromagnetic sensor, in a zero-indicator function and made in the form of an annular core with two windings, one of which carries the arc current and the other is a magnetizing service to output the operating point to the part of the characteristic that provides a sharp pulse at the time of the arc-induced current drop to zero.