DE135892C

DE135892C -

Info

Publication number: DE135892C
Application number: DENDAT135892D
Authority: DE

Description

PATENTAMT.PATENT OFFICE.

M 135892 KLASSE 21 e. M 135892 CLASS 21 e.

in PRAG-VYSOCAN.in PRAGUE-VYSOCAN.

Zur Aufnahme der Curvenformen von Wechselströmen bezw. allgemein zur Messung des Momentanwerthes von Strömen dienten bisher Vorrichtungen, welche meistens auf dem Princip der bekannten Joubert'sehen Contactscheibe beruhten. Die Schwierigkeit der Herstellung eines momentanen elektrischen Cöntactes und die nothwendige grofse Empfindlichkeit des Mefsgeräthes bilden Nachtheile dieser Methode, welche bei der vorliegenden Erfindung dadurch vermieden werden sollen, dafs der elektrische Contact gewissermafsen durch einen magnetischen ersetzt wird. Eine ähnliche Vorrichtung, bei welcher eine Contactscheibe dadurch vermieden wird, dafs die Aufnahme vermittelst einer gegenüber einer Primärspule umlaufenden Secundärspule geschieht, ist bereits durch die deutsche Patentschrift 93257, Kl. 21 bekannt geworden.To record the curve shapes of alternating currents respectively. generally for measuring the The momentary value of currents has hitherto been used by devices, which are mostly based on the principle of the well-known Joubert's contact disc. The difficulty of making of a momentary electrical contact, and the necessary great sensitivity of the measuring device are disadvantages of this method, which in the present invention are to be avoided by that the electrical contact is to a certain extent replaced by a magnetic one. One Similar device in which a contact disc is avoided by the fact that the Recording takes place by means of a secondary coil rotating opposite a primary coil, has already become known from the German patent specification 93257, class 21.

Die vorliegende Anordnung ist nun so getroffen, dafs ein zu analysirender Wechselstrom der Primärwicklung S₁ eines kleinen Transformators T zugeführt wird und in dem Eisenkörper F desselben einen wechselnden magnetischen Kraftlinienflufs erzeugt. Der magnetische Kreis, der durch F gebildet wird, ist nun nicht — wie bei gewöhnlichen Transformatoren ·— geschlossen, es fehlt vielmehr eine Seite des Joches. Aufser den primären Windungen S₁ trägt der Transformator noch secundäre S₂, welche an ein Wechselstrom-Voltmeter Mangeschlossen sind. Ordnet man diesen Transformator feststehend gegenüber einer synchron mit dem Wechselstrom rotirenden, nicht magnetisirbaren Trommel R so an, dafs die offene Seite von F der Trommel zugekehrt ist und bettet an einer Stelle der Trommel ein Eisenstück A ein, welches geeignet ist, den magnetischen Schlufs für den Eisenkörper F zu bilden, so findet einmal pro Umdrehung, und zwar nur momentan, ein Schliefsen des magnetischen Kreises statt. Diese momentane Verbesserung der magnetischen Verhältnisse hat, wenn S₁ vom Wechselstrom erregt wird, einen Inductionsstofs zur Folge, welcher sich in S₂ durch eine mittelst des Voltmeters M mefsbare Spannungsinduction äufsert, und welcher um so gröfser wird, je gröfser der augenblickliche Werth des erregenden Wechselstromes ist. Die Gröfse des letzteren kann also durch den Ausschlag des Voltmeters gemessen werden. Dadurch, dafs man den Transformator T stetig in Richtung der Trommelperipherie verschiebt, erfolgt die Induction in einem sich stetig ändernden Zeitpunkt der Periode des Wechselstromes, und man ist so im Stande, die Curve des letzteren aufzunehmen.The present arrangement is such that an alternating current to be analyzed is fed to the primary winding S _{1 of} a small transformer T and generates an alternating magnetic flux of lines of force in the iron body F of the same. The magnetic circuit, which is formed by F , is now not - as with ordinary transformers - closed, rather one side of the yoke is missing. In addition to the primary turns S ₁ , the transformer also carries secondary S ₂ , which are connected to an alternating current voltmeter M. If this transformer is arranged in a fixed position opposite a non-magnetizable drum R rotating synchronously with the alternating current, so that the open side of F faces the drum, and a piece of iron A is embedded at one point on the drum, which is suitable for the magnetic closure To form the iron body F , the magnetic circuit closes once per revolution, and only momentarily. This momentary improvement in the magnetic conditions, when S _{1 is} excited by the alternating current, results in an induction substance which manifests itself in S ₂ by a voltage induction measurable by means of the voltmeter M , and which becomes greater the greater the instantaneous value of the exciting one AC is. The magnitude of the latter can thus be measured by the reading of the voltmeter. By moving the transformer T continuously in the direction of the drum periphery, the induction takes place at a continuously changing point in time of the period of the alternating current, and one is thus able to record the curve of the latter.

Die in der beiliegenden Zeichnung dargestellte Vorrichtung kann auch derart abgeändert werden, dafs die Secundärwindungen S₂ auf dem rotirenden Theil A des ferro-magnetischen Kreises angeordnet werden, wodurchThe device shown in the accompanying drawing can also be modified in such a way that the secondary windings S _{2 are arranged} on the rotating part A of the ferromagnetic circuit, whereby

Claims

the induction of a voltage in S ₂ during the time when F and A are not facing each other is avoided.

The constant mutual induction between S ₁ and S ₂ , caused by the incompletely magnetic impermeability of the air, produces a constant deflection at M , which is to be taken into account as a correction. With an appropriate arrangement of shielding copper sheets, this correction value can be reduced to a very small amount.

A shift in T can be avoided by not letting the shaft W of the drum S rotate exactly synchronously, e.g. B. in such a way that the same keyed onto the shaft of an asynchronous three-phase motor. As a result, the point in time of the magnetic contact shifts automatically over the entire period.

Instead of a coil S ₁ respectively. S ₂ , several of them can be attached, instead of an iron socket piece A, any number.

Pa τ ε ν τ - A ν s γ r ü c ii ε:
A device for measuring the instantaneous value of periodic electrical currents, consisting of a (primary) coil S ₁ excited by the current to be measured and a secondary coil S ₂ connected to a measuring device , in which an instantaneous value of the exciting current to be measured is proportional or has a known function induction material dependent on it, characterized in that a piece of iron A moves in relation to a fixed iron yoke F , which carries the primary and secondary coil, and causes the induction material in S ₂ through the momentary field intensification and weakening (when passing through the movable piece of iron).

An embodiment of the under i. marked device, consisting in that the secondary coil S _{2 is arranged} on the rotating part A of the magnetic circuit.

For this purpose ι sheet of drawings.