DE1040125B - Circuit arrangement for monitoring a voltage - Google Patents

Description

GERMAN

The invention relates to a circuit arrangement for monitoring a voltage by comparison with reference voltages and for signaling at least two voltage values of a DC or AC voltage source. Such circuits are often used in electrical communications and measuring technology required.

The multiple carrier frequency systems used for message transmission are so-called Pilot monitoring devices provided, which have the task of emitting a signal or a Control process when the pilot level at the output of an amplifier by more than a certain Amount deviates from the target value. In many cases, not every amplifier has its own Device monitored, but several amplifiers are scanned by a selector-like organ, which means that only one pilot receiver is required instead of many. The rotation time of the scanning element and thus the sampling time of an amplifier must be short if you want to achieve a level error without large delay is reported or regulated. This requires that fast-switching relays such. B. Telegraph Relays, must be used. It should also be noted that the level maintenance in the individual amplifier offices in modern communication systems increased demands are made. Up until now it was sufficient to signal level deviations of 0.5 neper with an accuracy of ± 0.1 neper, see above it is now required that a deviation of 0.2 neper should be reported with an accuracy of ± 0.02 neper. With simple Telegraph relays, the response tolerance of which is approximately ± 20%, can achieve such an accuracy can no longer be easily achieved. The moving coil relays, which respond very precisely, are too slow and require a telegraph relay in the sequential circuit.

It is known that when telegraph relays are used in the usual monitoring circuits, one responsive to the respective relay tailor-made comparison. It is cumbersome and would have to be repeated when the relay is changed be made. In addition, the response value assumed during calibration does not remain at the Sustained, especially when excitations are offered to the relay that are well above the response value because the contacts are then mechanically deformed.

A circuit according to FIG. 1 is also known with which it is possible to keep the relay excitation up to a certain value of the monitored voltage U at O ¹ and to let it rise sharply above this value within a very small voltage range, like this Fig. 1 a shows. Circuit arrangement is used
for monitoring a voltage

Applicant:
Siemens & Halske Aktiengesellschaft,

Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Dipl.-Ing. Georg founder, Munich-Großhadern,
has been named as the inventor

here the non-linearity of a rectifier Gl , which is biased in the reverse direction by the voltage U _{2 present} at the voltage divider R ₀ ZR _2. A current can only flow through the relay F when U ₁ > U ₂ . U ₀ is a fixed reference voltage, U _{2 is} the reference voltage derived from it. The relay F will close its contact / when the excitation Jw reaches or exceeds the response value (Jw) _0. If (Jw) _{n is} the nominal response value of the relay and α is the response tolerance, then (Jw) ₀ lies in the hatched area (1-a) (Jw) _n to (1 + a) (Jw) _n of FIG. If U _{A is} the voltage value to be signaled by making contact with f, then the signaling will be more precise, the steeper the / w curve at U ^> U ₂ and the smaller (Jw) _n and α can be. The steepness of the excitation curve is increased by low relay resistance R, high voltage U ₂ and small internal resistances in the voltage sources supplying U ₁ and U _2.

These facts are also used in the circuit according to FIG. Here, compared to the circuit described above, by inserting the resistor R _1, the excitation curve according to FIG. B. at 0.9 Un and at 1.1 Un, if Un is the setpoint of the voltage U to be monitored. Both circuits mentioned have in common that the excitation is limited below a certain value of U , so that the relay contact / is mechanically protected if the voltage U fails.

It is also a circuit arrangement for displaying the deviations of a voltage from a constant setpoint by means of a polarized relay with two windings has been proposed in which

809 640/205

3 4

the two windings in opposite directions one behind the other - signaling voltage values largely independent

switched and is pending with its free ends with one each. While in the adjoining

Input terminal are connected, while their passing the excitation in the case of small voltage changes.

connection point changes very quickly via two oppositely polarized equations, which increases the accuracy

judges, each of which has an adjustable resistor in front of the 5 signaling of the response variance of the

is switched. with the other two terminals, the relay becomes largely independent

is bound. intermediate areas with preferably con

Considerations within the scope of the invention led to constant excitation, this accuracy of signaling

a circuit according to FIG. 3, in which, according to the diagram, also to be maintained when the to be signaled

According to FIG. 3a, the excitation at high values io voltage values can also have any distance. A

can be limited by U by having an excitation curve that fulfills these conditions

second rectifier G / 2 in series with winding F I in the simplest case, and if only two voltage

of relay F switches. Thus, compared to Fig. 2 a, values are to be signaled, two points of discontinuity,

the excitation J ₁ W _{1 is} limited to the value 0, if hereinafter referred to as "kink", and this

£ * ₁ > L ^T ₆ will. In order to also signalize two 15 are at the ends of an area, for example the

To enable voltage values of U , the excitation will have 0. This area in turn lies

J ₁ aj curve (dashed in Fig. 3 a) by the con between the two voltage to be signaled

constant excitation /., W ₂ (dash-dotted) in the Wick values. If you want below the one and above

ment F II shifted so that the other of these voltage values in FIG. 3a causes the excitation

drawn resulting excitation curve results. 20 limit, the course of excitation must be four

Have the circuits shown, especially the kinks. Considerations about the last to be made, including the advantage of the excitation limitation, show the measures that one equal per kink, but they all have one disadvantage in common: Will straightener and a fixed reference voltage and for each one - as mentioned in the circuit according to FIG. 2 - two kinks at least one relay winding is necessary, for example a signal at 0.9 Un and that are on. If there is no limitation, it can be reached at 1.1 Un , so the slope with four kinks in three, with six kinks in four of the earth voltage values, which change linearly with voltage U , etc. give a signal. Defined for each limitation of the excitation process, since the nominal response values outside of the voltage values to be signaled ± (/ «. ')» Are given by the relay. Another kink is required here. If you agree with the response tolerances a, that is to say the 30, there are also areas of constant Er-Fig. 2a given. Due to the requirement to provide for signal excitation, it is possible to get by with fewer kinks in the voltage values that are possible in the excitation process.
If the voltage to be monitored is an alternating excitation curve between the specified voltage, one of the values used to achieve the kink can be linear. The response error increases by the amount of rectifier required to convert the alternating signals, the flatter the excitation curve is, that is, it is also used in a direct voltage. Since, as the further the voltage values to be signaled have already been mentioned, the reference voltages and thus are separated from each other. If, as mentioned at the beginning of the voltage to be monitored, a signaling at 0.2 neper under-, which should probably be high, is required by the steepness of the excitation earth at 0.2 neper over-level, then it must be at In certain cases, before relays with a response tolerance α = 20%, the rectification of an AC voltage accuracy of at least + 0.04 neper with a known voltage doubler circuit is not a problem. This is the same inaccuracy to make. This is necessary above all where only the rectifier with limited blocking voltage values, even with the usual monitoring circuits 45, without excitation limitation occurs. z. B. Crystal diodes when rectifying high fre-

According to the invention, one or two equal sequences are available. Such a rectifier, as well as a resistor and a fixed converter circuit, can also replace one of the rectifiers required to generate one of two or more rectifiers for the buckling DC voltage.
Windings of an unpolarized or polarized relay 50 It is advantageous to assign the voltage to be monitored in such a way that the series connection supplies a low internal resistance to the winding from a source and a rectifier. If it is an alternating voltage, then a point with a fixed reference potential and this is found to be useful to keep this internal resistance at one end of a resistor which, from the voltage that is to be monitored by a voltage negative feedback, is held by a further DC voltage. The input resistance of the monitoring converter is fed and the rectifier has the function of a hyperbola, speaking polarity depending on the voltage to be monitored when it is applied depending on the monitored level of the voltage to be monitored. One asymptote lies parallel to correct values, which through the comparison axis to the resistance axis and intersects the voltage voltage, the size of the resistance and the winding axis at the voltage value determined in the excitation resistance, current-carrying or corresponding to the first kink. Below this are de-energized, such that the excitation of the relay voltage, the input resistance is infinitely large, depending on the voltage to be monitored Voltage values a selectable range 65 input resistance, which results from an infinitely large input voltage with one of the adjacent ranges. This minimum input-different excitation curve, in particular with a resistor, should have at least twenty times greater than constant excitation, and the accuracy should be that of the internal resistance of the amplifier output.
Signaling both of the response spreads of the relays required to generate the kinks and of the mutual distance between the reference voltages should expediently be low

Internal resistance can be supplied. It is advantageous to take them from a voltage divider, whose Cross current is large compared to the relay winding currents. It should be at least ten times larger than the total the winding currents must be at the highest voltage to be monitored. As it is in most cases The voltage divider is used to provide the signal with absolute voltage values expediently placed on a stabilized voltage.

The course of excitation in the relay must be ίο correct values of the voltage to be monitored a predetermined amount of excitation, e.g. B. the Value 0 or the nominal response value. Since these excitation values are due to the kink formation alone can not always be achieved, it is desirable that the course of excitation is in the excitation-voltage axis cross can be moved or rotated. A shift perpendicular to the voltage axis is caused by a relay winding that is driven by a corresponding constant current is passed through which, for example, stabilized the one mentioned above Voltage source is taken. If, on the other hand, such an additional winding is made by one If current flows through it, which is proportional to the voltage to be monitored, a rotation takes place the course of excitation in the axillary. Another possibility of variation for the course of excitation results by changing the number of turns and winding resistances of the individual relay windings and by the fact that the fluxes generated by the individual windings, if necessary, in can act in the same or opposite direction.

The invention is explained in more detail with reference to the exemplary embodiments shown in FIGS.

In the circuit according to FIG. 4, three rectifiers G / l to Gl 3, two windings FI and / ⁷ II and three reference voltages U _a , U _b and U _{c are} used in order to be assumed here as an alternating voltage, depending on the voltage to be monitored U. - · To achieve excitation in the polarized relay F , as shown in FIG. 4 a. The reference voltages J7 & and U _c are tapped at the voltage divider R ₀ IRJR _-2 , which is connected to the stabilized voltage JJ ₀ . As long as the applied alternating voltage U is so small. that GIl remains blocked, the reference voltage U ₀ drops at R ₁ , the magnitude of which results from U _b and the division ratio of the winding resistance _{of PIZR 1} . In this area of U FI flows through the independent stream of U Z _1, which generates the constant excitation shown in Fig. 4a in the relay F. The current J ₂ flowing through the winding FII is 0, since G / 3 is blocked by U _c. If U rises so far that the voltage drop across R _{1 is} greater than U ₁₁ , then J ₁ will decrease and so will the excitation in F. If U ₁ = U _b , then J ₁ = 0, and relay F with it without excitement. This state remains initially even if U _{1 is} greater than U _b , since G / 2 blocks. G / 3 remains blocked as long as U _{1 is} less than U _c . Only when U _{1 is} greater than U _c does a current J ₂ begin to flow through the winding FII, as a result of which the excitation - depending on the polarity of FII - increases in a positive or negative direction if U continues to grow. After explaining the circuit of FIG. 4 it is clear that it is possible through the choice of the reference voltages, a so extend the range of the excitation 0 in Fig. 4 that the distance can be arbitrarily selected to be signaled voltage values of U without the accuracy of the relay address is thereby affected. This is given solely by the steepness of the adjacent excitation areas, whereby the steepness only depends on the winding and current measurement. In the circuit according to FIG. 4, the excitation is limited at low voltages U. FIG. 5 shows a circuit in which, using a further rectifier, there is also a limitation at high voltage values of U.

In this circuit, when the voltages U are low, the currents J ₁ and J ₂ flow through the windings FI and FII; they are independent of U as long as CZ ₁ does not exceed U _11. If U ₁ = U _b , then J _{1 has} become 0, the excitation in F is only determined by J ₂ . If U ₁ rises above the reference voltage U _c , then J ₂ decreases, in order to finally become zero at U ₁ = U _d. The excitement in the relay F remains 0, even if U still growing because the rectifier Gl 2 and Gl4: lock. E'ig. 5 a shows the corresponding excitation curves, drawn in solid lines when FI and FII generate fluxes in the same direction, and dashed when the two windings are connected to one another. This shows which variations can be achieved by reversing the polarity of a winding. In addition, after what has been said, it is understandable that further modifications are possible by changing the number of turns, ratios and the winding resistances. The solid excitation curve according to FIG. 5 a does not yet allow two voltage values to be signaled separately when using a center-position contact / since work is only carried out in the area of positive excitation. With the aid of a further winding FIII, indicated by dashed lines in FIG. 5, through which a constant current flows, it is possible, however, to shift the course of the excitation so that it corresponds to that shown in FIG. 5b.

One can now imagine that with the help of further rectifiers, reference voltages and windings it is possible to achieve further kinks in the course of excitation. For example, the series connection between U _a and U _c in FIG. 4 of a rectifier and a winding of F in FIG. 5 can be placed between U _c and U ₀ . If U ₁ then becomes greater than U ₀ , a current would begin to flow through this additional winding of F which can again reduce the negative excitation value shown in FIG. 5 b, which is limited at high voltages U. The contact / placed on one side would open again at a third, high voltage value and thus be able to signal this value.

The circuit according to FIG. 6 is intended to give an example of how it is possible, with the aid of a winding FI through which a current proportional to the voltage to be monitored flows, to modify a step-shaped excitation curve generated according to FIG. 5a so that it becomes sawtooth-shaped , as shown in Fig. 6a. If the voltage U ₁ across the capacitor C and thus across the resistor R ₁ becomes greater than U ₀ , the originally flowing current J _{1 is} reduced. As a result of the resistor R _{1 connected} upstream of the FI and the high reference voltage U ₂ , the corresponding change in excitation, shown in dashed lines in FIG. 6 a, is very flat. The excitation curve generated in the windings FII and FIII with the aid of the rectifiers GIl to G / 4 corresponds to that of FIG. 5a (solid line); it is shown in phantom in FIG. 6a. The resulting excitation curve is shown in solid lines in FIG. 6 a. If a relay with a center-position contact f, which is switched as in FIG. 6, is used again in this circuit, it becomes

Set contact for certain ranges of the voltage U , but none for those in between. This arrangement can be used to signal a time-dependent rise in the voltage U to be monitored, as shown for example in FIG. 6b, via a line by means of a pulse telegram.

Claims (7)

PATENT CLAIMS: 1. Circuit arrangement for monitoring a voltage by comparison with reference voltages and for signaling at least two voltage values of a direct or alternating voltage source, characterized in that one or two rectifiers (672, G / 3) and a resistor (R ₁ ) and a fixed reference voltage (U _b , U _c ) are each assigned to one of two or more windings (/ • "I. / ⁷ II) of an unpolarized or polarized relay in such a way that the series connection of a winding (FI or FII) and a rectifier (G / 2 or G / 3) lies between a point with a fixed reference potential and the one end of a resistor (R ₁ ) which is fed by the voltage to be monitored (U) via a further rectifier (GH) and the rectifier (GIl, G12, G / 3) by corresponding polarity depending on the level of the voltage to be monitored (U) at certain values, which are determined by the comparison voltage, the size of the resistance and the winding resistance b are determined to be energized or de-energized, in such a way that the excitation of the relay is discontinuous depending on the voltage to be monitored (U) and between two of the voltage values to be signaled there is a selectable range with an excitation curve different from the adjacent ranges, in particular with a constant Excitation, and the accuracy of the signaling is largely independent of both the response spread of the relay and the mutual distance between the voltage values to be signaled (Fig. 4). 2. Circuit arrangement according to claim 1, characterized in that one of the relay windings associated rectifier is also used to rectify an alternating voltage. 3. Circuit arrangement according to claim 1 or 2, characterized in that to increase the Response accuracy the voltage to be monitored from an alternating voltage through a Voltage doubler circuit is generated through which at the same time one of the relay windings connected rectifier is replaced. 4. Circuit arrangement according to one of claims 1 to 3, characterized in that the voltage to be monitored is supplied from a source with low internal resistance AC voltages in particular through a negative voltage amplifier with a compared to the lowest input resistance of the monitoring circuit at least twenty times smaller internal resistance. 5. Circuit arrangement according to one of the preceding claims, characterized in that the reference voltages (U _b , U _c ) required for comparison are taken from a voltage divider (R ₀ , R ₂ , R ₃ ) whose Ouerstrom is at least ten times higher than the sum of the through all relay windings (FI, FII) flowing currents (Z ₁ , J ₂ ) is at the highest possible value of the monitored voltage (U) , and that the voltage divider is fed by a stabilized voltage source (U ₀ ) (Fig. 4). 6. Circuit arrangement according to claim i, characterized by the use of further windings (FIII) the monitoring relay in such a way that it is from one of the voltage to be monitored proportional and / or flowed through by a constant current, whereby the excitation of the relay at certain values of the voltage to be monitored a specified amount, in particular reaches the amount 0 (Fig. 5, 5 b). 7. Circuit arrangement according to claim 1, characterized in that of the rectifiers connected relay windings one or more generate a flow directed against the other (s) and that the course of excitation depends on the voltage to be monitored is determined by this and by the choice of the number of turns and winding resistances. Legacy Patents Considered:
German patent Xr. 1,013,786. 1 sheet of drawings 1 809 640/205 9.58