DE202013C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- Yes 202013 CLASS 21 e. GROUP

ERICH GANTZER in CHARLOTTENBURG.

Patented in the German Empire on November 1, 1907.

The subject of the invention is an instrument which directly determines the power factor cos φ for AC systems. As is well known, you have it up to a certain point Just in hand to change the power factor of a plant by using synchronous motors switched on, which, with suitable excitation, allow the voltage and current curves to be shifted relative to one another,

ίο so that thereby to a certain extent keeping the power factor constant despite changes in the inductive load on the machine can be achieved. It is therefore of the utmost importance that the supervising machinist be informed immediately becomes, if 'with a changing load there is a change in the power factor entry. This is to be achieved according to the invention in that a Wattmeter and an ammeter with the power or amperage proportional torques on a common display device act in such a way that the power factor can be read directly from the latter can be.

In the drawing, on which the subject of the invention is shown schematically, α denotes the axis of a Ferraris performance indicator, e the axis of a hot-wire ammeter. On each of these axes, a sector S ₁ or S ₂ with a limiting curve is fixed, the course of which is determined by the equation ψ = e ^ar , if ψ is the angle of rotation and r is the distance from the o-point of the coordinate system. Each of these curve sectors is in engagement with a one-armed lever Z ₁ or Z ₂ , which can rotate about the associated pivot points b and /. A rod u or u. _{2 is} connected to the movable ends of these levers at points c and g , and at their other ends these rods are articulated to a double-armed lever ν swinging around axis 0 at points d and h , which is under the action of a helical spring n> placed on the axis 0, which strives to keep the double-armed lever always in a certain position. On the axis 0 there is a pointer \ that plays over a scale. The free ends of the levers Z ₁ and Z ₂ are under the action of springs m _x and Wi ₂ , which keep the levers Z ₁ and Z ₂ permanently in engagement with the curve sectors S ₁ and s _{2, respectively.} As soon as the system is energized, both the power indicator and the hot-wire ammeter come into action, and their axes try to turn in the direction indicated by the arrows. The curve sector S ₁ tries to rotate the one-armed lever Z ₁ , and the curve sector S ₂ , the one-armed lever Z ₂ to rotate about its pivot point b or f. As a result, in the arrangement of the drawing, a tensile force is exerted on the double-armed lever ν by the rod u , which tries to turn this double-armed lever counterclockwise, and through the rod M ₂ a tensile force that the double-armed lever ν in the sense of Looking to turn clockwise. The deflection of the double-armed lever will

Claims (1)

that is, proportional to the difference between the forces P ₁ and P ₂ that occur. The following consideration shows how it will be possible in this way to use the device described above directly for displaying the power factor cos φ. The two forces P ₁ and. P ₂ a torque is exerted on the double-armed lever ν , which is the equilibrium ίο is held by an oppositely directed torque of the torsion spring n> . This torque is directly proportional to the difference between the forces P ₁ and P ₂ multiplied by a constant, so that the equation can be written: M = C ₁ (P ₁ -P ₂ ). This moment is also directly proportional to the angle, with sufficient certainty it is assumed that the tension of the coil spring changes proportionally with the angle. So it is M = c a, where C _{2 is} a constant of the spiral spring. This results in the equation: consequently: (Ι ·)
whereby P ₁ -P ₂ = c _a -a, c "= L ₂ . Cj is. P ₁ and P ₂ are proportional to the deflection of the levers t _Y and f ₂ , because they are under the action of the springs In ₁ and Wi ₂ , the tension of which changes proportionally to their length. At the same time, the forces P ₁ and P _{2 are} also directly proportional to the polar coordinates τ of their curve sector. One can therefore set up the equation: ^p i = ^c i ' ^r i ^{and p} 2 = C ₅ r ₂ , consequently: (II.) P ₁ -P ₂ = C ₄ T ₁ -C ₆ T ₂ . If C ₄ = C ₅ is now chosen, the result is the equation: P ₁ -P ₂ = C ₄ -Cr ₁ -T ₂ ).
From equation (I.) it also follows that
C ₄ · (T ₁ -r ₂ ) = c ₃ .a is, it follows: (III.) T ₁ -T ₂ -C ₆ -K, , whereby
60 is set. But r is connected to the angle of rotation ψ by the equation: consequently: ψ = e ^ar r = (1: a) In ψ, T ₁ - = (ι : Ci ₁ ). In . ψ _ν
T ₂ = (ι: a ₂ ) In - ψ ₂ , where Xp ₁ and ψ _{2 are} the angles of rotation at which the watt pointer and the ammeter are set. The power Is · / «cos φ indicated by the watt pointer is proportional to the torque of the instrument, but this is directly proportional to the angle of rotation Xp ₁ . Hence one can set: Xp ₁ = C ₇ * E * I * COS φ. If one now considers E to be constant, which is permissible for many cases, the equation changes: Xp ₁ - C ₈ 7- COS φ, and, if the angle of rotation xp ₂ changes in direct proportion to the current I in the ammeter, C ₉ - /. T ₁ - T ₂ = C ₆ α = C ₁₀ In (/ cos φ) - c, ■ In. I. Ct = C ₁₁ - In '(Ι cos φ: I), Combining this with the equations above results in: T ₁ = C ₁₀ Wn- (I-COS φ),
T ₂ = C ₁₁ · In · 7, whereby the constants C ₈ and C _{9 are also} taken into account in C ₁₀ and C _11.
Then: If C ₁₀ and C ₁₁ are equal, it follows: a = C ₁₂ - In cos φ, ^C 12 ⁼⁼ ' ^C 6 consequently: (V.)
whereby This proves that, with a suitable choice of the constants, In · cos φ can be displayed directly by the pointer. So it is only a matter of classification in order to read off the cos φ directly. In order to take into account the influence of the variable E for the measurement of cos φ in the case of strongly fluctuating voltage, a voltmeter can be installed in exactly the same way as the instruments described above, which in the same sense as the Ammeter acts on the common display device, so that Ψ3 = ^c is' ^E > = c, ■ In · E, whereby