SU58419A1 - Spark gap valve discharge - Google Patents

Description

Spark gaps of valve gaps for the protection of generators are already known, consisting of several suppressive spark gaps with disk electrodes and one additional spark gap in series in a common insulating jacket. In such discharges, a condition must be observed, usually characterized by the magnitude of the pulse coefficient and the characteristic of the discharge voltage in the selectivity with respect to the pulse effects.

In other words, the spark gap of the spark must have a frequency response of the discharge voltage.

At short discharge times, the discharge voltage should not exceed the isolation level of the protected object; At the same time, at all lower frequencies, which characterize switching and arc overvoltages, the arrester should not come into action in order to avoid its destruction and the occurrence of an accident.

In addition, the spark gap of the discharge current must have a characteristic that allows it to reliably cope with the arc extinguishing from the conducting current.

The present invention aims to implement such a discharge and consists in the fact that the interelectrade capacitance of the additional spark gap is chosen two to three times smaller than the interelectrode capacitance of a single quenching gap, and the discharge voltage is approximately 50% larger. As the author points out, with this type of discharge, the latter, satisfying the conditions of selectivity, has a pulse ratio less than one, while the discharge voltage of the gap does not exceed the guaranteed level of insulation of masses, which is known to be relatively low compared to the degree of isolation of the rest of the station electrical equipment.

In FIG. 1 depicts a schematic diagram of the proposed spark gap; FIG. 2 is a spark gap diagram using resistors shunting additional and suppressive gaps; FIG. 3 and 4 is a view in two projections of the valve gap assembled according to the scheme shown in FIG. 2; FIG. 5 is a perspective view of the gap of FIG. 3 and 4 with the cover removed.

The discharge circuit consists of consecutively connected unit gaps with a developed interelectrode capacitance Cd and one or several additional gaps, having a smaller (approximately two to three times) intertelectrode capacitance Ci (Fig. 1). The discharge voltage U- of the additional gap is chosen larger (by about 50%) than the discharge voltage / 2 of each of the main intervals.

The frequency dependence of the circuit can be given to specially selected high-resistance,, (Fig. 2), shunting additional and suppressive gaps. The ratio between capacitive and ohmic conductivity is chosen so that at low frequencies the distribution of voltage between the main and additional intervals controls the ohmic resistance. At the same time, the ratio of the conductivities of the ohmic shunting of the main and additional gaps is established inversely proportional to their discharge voltage.

Due to this, at low frequencies, the discharge voltage of the entire gap is added up from the sum of the discharge voltages of the main and additional intervals.

At high frequencies (pulses), the distribution is determined by capacitances, and due to the fact that the additional gaps have a smaller capacity, the gradients on them grow faster than on the main ones, and the discharge on them occurs earlier. In this case, the gap is punched in a cascade, and the discharge voltage is no longer determined by the sum of all the discharge voltages of the individual intervals, but mostly only

the sum of the discharge voltages of the main gaps.

Obviously, the discharge voltage is less than at low frequency. The pulse factor is less than one.

Increased discharging voltage of additional electrodes is necessary to more fully utilize their share in increasing discharging voltage at low frequencies. However, an excessive increase is unacceptable, as it can prevent the onset of a cascade discharge during pulses. The damping capacity of such a gap is higher than that of a normal arrester, since the number of main gaps can be made the same, and in addition additional ones are added. At the same time, a uniform distribution of voltage between the main gaps, at any frequency, which is absolutely necessary for increasing the damping ability, is achieved by the identity of the neutral resistances and the electrode capacitances.

In addition, an increase in the latter compensates for the detrimental effect of the influence of parasitic capacitances on the ground, which affects a decrease in the damping properties of the discharge capacitor.

Structurally, the gap (and the discharge as a whole) is sufficiently niOCT (see Fig. 3-5) and can be made of combinations of simple parts, developed by industry and tested in exploitation. The design of the gammer, since the latter is sufficiently explained in FIG. 3-5 of the attached drawing, not shown.

The subject matter of the invention.

Claims (3)

1. A spark gap of a valve gap to protect the generators, consisting of several extinguishing spark gaps with disk electrodes arranged in a common insulating jacket and one additional spark gap, in series, characterized in that the additional gap has an interelectrode capacitance, two times smaller than the interelectrode capacitance of a single quenching gap, and the discharge voltage is approximately 50% larger, in order to reduce the pulse coefficient to less than one. 2. In the spark gap according to claim 1 the use of ohmic resistances, shunting additional and suppressive gaps, in order to apply an arrester to high voltages. 3. In the spark gap according to claim 2, apply resistors located on the outer surface of the insulating casing. Fig2 R , Ig y, 3If2U2, 12Пу 1 sz: /: g Fig 5.