DE746399C - Device for observing electric arcs of strongly changing light intensity. - Google Patents

Abstract

Observation device for strongly fluctuating electric arcs. The arc light passes through two polarization filters, between which there is a body that rotates the plane of polarization due to the action of a magnetic field. The magnetic field is influenced by the current or voltage of the arc.

Description

The invention relates to a device for the direct observation of electric arcs of strongly varying strength, for example in headlights, arc furnaces or arc welding machines. In particular for the latter purpose one has glasses made of very dark filters or plates to be kept available, but all of them have the disadvantage that when the arc is extinguished, which occurs in the event of an open circuit or a short circuit, another Observation through the filter devices is not possible. The overall observation then had to be done alternately with or without a filter, with the arc starting quickly strong glare occurred, which is then initially sensitive to further observation bothered. A filter that allows uninterrupted observation must be according to the following Table to meet three different conditions:

Idle...
Electric arc
Short circuit

current

tension

filter

According to the invention, a filter meeting these conditions becomes permeable by utilizing an effect discovered by Edison
weakly permeable
permeable

tes created, according to which the plane of polarization of a linearly polarized light beam in certain Substances through a magnetic

Field is rotated. If this field comes from the current in the arc or from it occurring voltage is dependent, an automatic control of the filter device can are executed.

The invention consists in a device for observing electric arcs of strongly changing light intensity, which is characterized in that the light of the ίο arc polarized through a polarization filter, then through one of a magnetic, 'in its strength of the current or the voltage of the arc body influenced by the dependent field, which rotates the plane of polarization according to the strength of the field, is guided and finally passed through a second polarization filter to the observer. This device corresponds to the arrangement shown in principle in the figure. The light of the arc B passing from an electrode E to a workpiece W first passes through a polarization filter P ₁ , from which it emerges linearly polarized. It then passes through a vessel G, which is closed at the ends by plane-parallel plates and is filled, _{for example, with carbon disulfide (CS 2).} The light then passes through a second polarization filter F ₂ , behind which the observer A is located. A coil S is arranged in the vessel G through which, for example, the welding current, a current branched off therefrom or a current corresponding to the welding voltage flows. When stroni flows through, the plane of polarization is rotated by an angle ψ = JdH , where k is the Verdet constant depending on the filler in the vessel, / the length of the filler passing through and // the magnetic field strength. With a sufficiently long coil, // = 0.3 · .τ, 'ni, if η is the number of turns in the coil and / is the current strength in amperes. Then the angle of rotation Ii = 0.3 · π 'knli. k is for CS ₂ -, so that there is φ · nli = 0.0435 = 0.041. With i _b = 200 A and / = 10 cm, the number of turns n = 15 ^{for an angle of rotation of 20 0. 1,} on the basis of these relationships, the second polarization filter P ₂ is rotated by ψ + oo °, so the field of view must remain dark. So you will not get any light from the welding point through the filter during the time in which the current i flows and so the arc shines strongly, or you will set the device so that only as much light gets into the eye of the observer as it is for the observation of the welding point or the otherwise interesting point is required.

According to a further embodiment of the invention, the use of certain liquid crystals is even more favorable than the use of carbon disulfide. It has z. B. Anisalamino - α - methylcinnamyl active amyl ester (Co ₃ H ₂₇ O ₃ N) has a Verdet constant of 0.938, that is, an effect that is about 22 times greater. In this case, it would be possible to achieve a higher angular rotation with a lower number of turns. The use of the thinnest iron layers, which are transparent with a thickness of 1 11 and less and whose Verdet constant increases up to 200,000 ° at magnetic saturation, is also very favorable. Such iron layers can be produced very evenly on a support without difficulty, in particular by vapor deposition in a vacuum.

Because of the existing dispersion of the effect, it will not succeed in the light of the Shield the arc completely. It is therefore necessary through an athermal glass to ensure that with security also the harmful ultrared and ultraviolet waves be kept from the eye.

The arc monitoring device Can be used as a fixed device on ovens or spotlights or, if necessary, on fixed ones Welds are arranged. It can also take the form of glasses, with either two of the glasses for each eye Vessels surrounded by a current coil and the associated filters are provided or one common arrangement extends over the area of both eyes.

The arrangement may also be made so that the arc current or the Lichthngeiispannung not be directly used to control, but that is connected between them and by the magnetic field ^lo ° Iweinflußten body to an amplifier arrangement. This amplifier arrangement can also work in such a way that a current arises on its output side which changes its value discontinuously after certain adjustable limit values on the input side are exceeded, but maintains its value in the event of small fluctuations on the input side.

Claims (8)

Patent claims: i. Device for observing electric arcs Light intensity, characterized in that the light of the arc in a polarization filter polarized, then by one of a magnetic, in its strength by the current or the voltage of the The arc-dependent field influenced the body that formed the plane of polarization speaking of the strength of the field turns, passed and finally by a second Polarization filter is fed to the observer. 2. Apparatus according to claim i, characterized by a filling of the through the magnetic field affected body with carbon disulfide. 3. Apparatus according to claim 1, characterized by the use of liquid crystals (for example C ₂₃ H ₂₇ O ₃ N) for the body influenced by the magnetic field. 4. Apparatus according to claim 1, characterized by the use of very thin iron layers up to τ μ thickness, which are preferably vapor-deposited on a carrier in a vacuum, for the body influenced by the magnetic field. 5. Device · according to claim 1, characterized through an athermal glass to filter out the ultra-red and ultra-violet Rays. - 6. Device according to claim 1 and the subclaims, characterized thanks to their design in the shape of glasses. 7. Apparatus according to claim 1 or the dependent claims. characterized, that between the extraction point of the current or the voltage of the arc and the magnetic field coil an amplifier arrangement is connected. 8. Apparatus according to claim 7, characterized in that the amplifier arrangement works in such a way that the current supplied to its output side after exceeding certain adjustable Limit values on the input side changes its value discontinuously, with small fluctuations but remains constant. To distinguish the subject of the application from the state of the art, the granting procedure no pamphlets have been considered. 1 sheet of drawings