SU917361A1 - Arc current increment sensor - Google Patents

Description

(5) ARC CURRENT GAIN SENSOR

one- .

The invention relates to a heat exchanger, and Oage has used a system of automatic adjustment of the electrically controlled arc 3s teK furnace system.

The arc current increment sensor is known, containing (a transformer with a pair of ja-booms connected in series and a pair of synchronizing windings connected to two impulse driver, each of the two outputs of which is connected to the base of one of the two key-shunting memory capacitors. ” The odes are connected to the working windings of the transformer and to the inputs of emulator repeaters, to the outputs of which is connected one of the bridge diagonals, made on transistor switches. the bridge is connected to a load capacitor, and the input of each transistor ch) is connected to one of the outputs of one of the two blocks

controls whose inputs are connected to the synchronization windings l.

Also known is the arc current increment sensor, which is equipped with a resistor connected in series with the load capacitor, in parallel with which an amplifier input is connected, to the output of which an additional capacitor connected in series and a transistor switch are connected.

10 The inputs of the additional pulse generator are connected to the outputs of the o6ovix control units, and the output is connected to the control input of the additional tran-,., Key 2.

15

A disadvantage of the known devices is that the storage capacitors remain charged when the input signal disappears to zero and the measured value of the increment

This arc current does not match the actual one.

The closest in technical essence to the proposed is

an arc current increment sensor containing two rectifying diodes connected to two series-connected capacitors, in parallel with which shunt control keys are connected, connected by outputs through dividing diodes to the emitter input of the repeater, and an RC differentiating circuit is connected in parallel with the output resistor , and a pulse shaper, two outputs of which are connected to the control inputs of the keys 3. The disadvantage of the described device is that become charged to the amplitude values of the last positive and negative half cycles of the input signal while decreasing it to zero (for example, an arc break). This does not allow to obtain the true shape of the amplitude envelope of the input signal and the value of its derivative.

The purpose of the invention is to improve the measurement accuracy by resetting the signal from the capacitors when the input signal disappears.

This goal is achieved by the fact that the pulse shaper is made in the form of a multivibrator, the input of which is connected to the anode of one and the cathode of another rectifying diode and serves as a sensor input, and the connection of the driver to the output key is made through a differentiating element - an RC-chain and additional dividing diodes

In addition, in order to improve the accuracy of the sensor, the connection of keys with the emitter follower can be made through an inverting amplifier.

FIG. 1 is a functional diagram of the arc current increment sensor; FIG. 2 shows timing diagrams explaining his work.

To the input of the arc current increment sensor (Fig. 1), capacitors 3 are connected via rectifying diodes 1 and 2 and, shunted by switches 5 and 6, and the input of the pulse former 7, made in the form of a multivibrator. To the input of the emitter follower with an RC-chain 8 are connected dividing diodes 9 and 10, between the capacitor 3 and the separating diode 9 an inverting amplifier 11 is turned on, and the output of the multivibrator 7 is through

a differentiating RC chain 12 and a pair of additional separation diodes 13 and I are connected to the control inputs of the shunt keys 5 and 6

The sensor works as follows.

A voltage proportional to the arc current is applied to the device input (Fig. 20). In negative half cycles, capacitor 3 is charged through rectifying diode 1, and in positive half cycles, capacitor C is charged through amplifying values of the input voltage through rectifying diode 2. These values are stored and held until the end of the respective current periods.

 In the presence of input voltage, the multivibrator 7 operates as a normal driver, converting the sinusoidal voltage into square pulses (Fig. 2 (5). These pulses are differentiated by RC-chain 12 and through a pair of additional separation diodes 13 and 1 short pulses (Fig. ) are fed to the control inputs of the shunt switches 5 and 6, which discharge the capacitors 3 and C, the voltage form on the latter is shown in Fig. 2. The voltage from the capacitor 1 and the inverted voltage from the capacitor 3 (output of the amplifier 11) through the separation diode s 9 and 10 is fed to the input of the differentiating circuit 8. This voltage is the envelope of the amplitude of the input signal (fig.2d), and the voltage at the output of the differentiating circuit 8 is proportional to the increment of the arc current.

When the input voltage disappears (tT-f moment, Fig. 2), the multivibrator 7 operates in the self-oscillating mode, generates rectangular pulses with a frequency equal to the self-oscillation natural frequency, and the capacitors 3 are discharged to zero with an insignificant delay.

The proposed device makes it possible to increase the accuracy of the measurement of the arc current increment, since when the input signal disappears, the differentiated envelope voltage ampgulth of the arc current after 1-2 ms becomes equal to zero.

Claims (2)

1. Sensor, arc current increments, containing two rectifying diodes. connected to two in series. connected capacitors, in parallel with which shunt controlled keys are connected, connected by outputs through dividing diodes to the emitter follower input, parallel to the output resistor of which is included a differentiating RC chain, the resistor of which serves as the output of the sensor, and a driver of the pulses, two outputs of which are connected with control inputs of keys, about tl and 4 and y y and with the fact that, with tse-. To improve measurement accuracy by resetting the signal from capacitors when the input signal disappears, the pulse shaper is designed as a multivibrator, the input of which is connected to the anode of one and the cathode of another rectifying diode and serves as an input to the sensor, and the specified link of the driver with each key is made through an additional differentiating RC-chain and additional separation diodes. 2. The sensor according to claim 1, which is distinguished by the fact that, in order to improve the accuracy, said connection of keys with The emitter follower is implemented through an inverting amplifier. Sources of information taken into account in the examination 1. Authorship certificate of the USSR ffSSa ZS, cl. H 05 B 7/1 tS, 1976. 2. USSR author's certificate №59588, cl. H 05 B 7 / H8, 19773. USSR author's certificate No. + 68108, cl. H 05 B, 1973. r - 9u9.2 1 I I II 11 GGT 11 in /, 4J j.