DE2160064B2 - - Google Patents

Description

3. Circuit arrangement according to claim 1 a pulse generator generated pulses in one or 2, characterized in that the Koinzi- 30 Voi warts down counters totaled or off circuit (5) is an exclusive OR gate. this one counted out. So the known circuit is

4. Circuit arrangement according to claim 1 constructed from similar elements, differentiates or 2, characterized in that the scanning differs, however, in its operation substantially from the circuit (8) has a flip-flop (16). Invention, which the technology by a further pre-

5. Circuit arrangement according to claim 4, enriched there- 35 partial solution.

characterized in that an output (Q) of the following are some exemplary embodiments

Flip-flops to a first input of an AND explained in more detail with reference to the drawings. It shows Gate (17) is connected and that the Ab- F i g. 1 shows a circuit arrangement for measurement

probe generator (10) via an inverter (18) with electrical energy and
a second input of the AND gate (17) 40 Fig. 2 and 3 circuit variants thereof,
connected is. In FIG. 1 mean 1 and 2 modulators that

Generate a pulse sequence / „or / ₍ . Here is the ratio of the difference to the sum of the pulse duration

and pause duration of the voltage «or the current /

45 proportional. Modulators of this type are known and therefore do not need to be explained in more detail here. The modulators 1, 2 are one at inputs 3, 4

The invention relates to a circuit arrangement connected to Koinzidenzschaltunig 5, which here is a for measuring electrical energy through product image AND gate. One of the outputs of the coincidence formwork from voltage and current by means of a statistic 5 leads to a first input 7 as see coincidence method, especially designed for an AND gate sampling circuit 8, their electronic electricity meter. second input 9 to a sampling generator 10

When one is closed by the Swiss patent specification. This generates narrow sampling pulses 16 ° known circuit of this type are two with the pulse repetition frequency j ,. An output 11 of the pulse trains, their pulse frequency or their pulse 55 sampling circuit 8 is connected to an up-counting input pulse width with the voltage or with the current 12 of a pulse counter 13. A backward modulation is checked for coincidence. The middle counting input 14 of the same is via a coincidence duration of the two signals corresponds to 15 with the reduction ratio 4: 1 at the electrical output. Coupled by scanning the coincidence generator 10.

Denzsignals with narrow pulses of constant duration 60 For the pulse duration <5 _{t of} the pulse frequency from the modulator 1, a pulse sequence results whose generated pulse sequence / "applies
mean pulse frequency a measure of the electrical y

Represents achievement. The electrical energy can be given by <5i = --- ■ + k _x ■ u,

Counting these pulses can be determined. ²

When measuring energy in an alternating current 65 where T _{i is} the period and _{Jc 1 is} a constant network, the impulses are added using the help.

a forward-backward counter. Analogously, two sign detectors are provided for the pulse duration ^ ₂ , which dr> sequence /,

■ I.

The probability p that at any given moment both a pulse of the pulse train / "As well as a pulse dsr pulse train /, is present, is

τ /

k, -i

The output signal of the coincidence circuit 6 is sampled _{at the frequency / r.} The following applies to the mean pulse frequency / _{m of} the pulses occurring at the output 11 of the sampling circuit 8

2T ₁

2T ₂

The alternating components representing elements -—, - and -J - ^ .- drop out in the case of communication over a full period of the network frequency. Since from the pulse counter 13 with the frequency '. constant impulses

are counted out, the result for the mean output frequency f _{a of} the pulse counter is:

^ d. H.

f _a f _r

T ₁ -T ₂

With u = 0 and i = 0, O ₁ = - £ - and 02 = ^

the pulse trains / „and / are exactly symmetrical. An asymmetry that z. B. can occur due to temperature or aging effects of the components of the modulators 1, 2, directly causes a zero point error in the energy measurement. The first-order asymmetry error can be compensated for in a simple manner in that the coincidence circuit S determines both the coincidence of the pulses and the coincidence of the pulse gaps of the two pulse sequences / ", / ₍ . A circuit arrangement of this type is shown in FIG. 2, which only differs from FIG i g. 1 twice as large. The downcounting input 14 is therefore given the frequency here

Y supplied.

If the symmetry error of the pulse train / ,, _{is denoted by E 1} and that of the pulse train / _{is denoted by ε 2} , then the following applies

₌ Zi + ε ₂ + ki-i

The mean output frequency f _a then results

If not only the coincidence of the impulses, but

If that of the pulse gaps is also evaluated, the result is that only the product y ^ jr of the asymmetries of the two pulse sequences / „and / ₍ brings about a zero point error. However, this error is

extremely small, since in general _e , and ε, are already very small _{compared to T 1} and T _2.

In the circuits according to FIGS. 1 and 2 the pulses of the sampling generator 10 must be narrow compared to those of the modulators 1 and 2

zo given impulses. Furthermore, e.g. by appropriate design of the scanning circuit 8 or of the reducer 15, it is ensured that the pulses arriving at the downward counting input 14 compared to the counting up input 12

relevant impulses are shifted in time. In the following, on the basis of FIG. 3 shown how the Circuit designed with a relatively wide pulse generating sampling generator and simultaneously also the second of the mentioned conditions

can be met easily.

In FIG. 3 are the same parts as in the preceding drawings with the same reference numerals designated. The sampling circuit 8 has a D flip-flop 16 clocked by the sampling generator 10

on, the Q output of which is connected to a first input of an AND gate 17. The sampling generator 10 is connected to a second input of AND gate 17 via an inverter 18. The D input of the flip-flop 16 is connected to the output 6 of the Koin-

cidenz circuit 5 connected.

A change in state of the output signal of the coincidence circuit 5 is always positive Voltage jump of the next sampling pulse of the sampling generator 10 to the Q output of the flip-flop

16 transferred. A signal corresponding to the output signal of the coincidence circuit thus arises at the Q output Signal, the edges of which, however, coincide with an edge of a sampling pulse. When this signal is sampled in the AND

Gate 17 can therefore no longer influence the width of the scanning pulses on the result of the scanning exercise.

The inverter 18 has the effect that a pulse counter 13 which advances the pulse counter 13 at the forward counting input 12 The voltage jump only occurs on the falling edge of the sampling pulses.

1 sheet of drawings

Claims (2)

Determine signs of voltage and current and claims: via a switching logic, the counter in the case of a positive product of voltage and current in advance warning 1. Circuit arrangement for measuring electrical and, if the product is negative, in reverse direction shear energy through product formation from voltage 5 switch. voltage and current by means of a statistical coin- The invention is based on the object of a cidenzethod, in particular for an electrical solution to be found, which does without sign detectors and niche electricity meters, marked switching logic. It is characterized by two modulators (1; 2) to form two modulators each to form a pulse train, a pulse train (/ „; /,), with the ratio of io with the ratio of difference to sum of difference to sum of pulse duration and pause Pulse duration and pause duration of the voltage or duration of the voltage («) or the current (/) is proportional to the current, through a coincidence is proportional, through a coincidence circuit (5) circuit to determine the coincidence of the two to determine the coincidence of the two Im pulse trains _{, by a sampling generator and a pulse train (/ a} ; //), by a sampling generator 15 sampling circuit for sampling the output signal (10) and a sampling circuit (8) for sampling the coincidence circuit and by a pulse des Output signal of the coincidence circuit (5) counter, its up-counting input to the output and through a pulse counter (13), its upstream of the sampling circuit and its downward-facing counting up counting input (12) to output (11), the output is coupled via a reducer to the sampling generator sampling circuit (8) and its down counting 20. input (14) via a coaster (15) to the US Pat. No. 3,470,471 Sampling generator (10) is coupled. already a circuit arrangement for measuring electrical 2. Circuit arrangement according to claim 1, detrical energy has become known in which two Im through characterized in that the coincidence switching pulse sequences are proportional to the input variables tion (5) to determine the coincidence of the ratio of the difference to the sum of the pulse duration pulse and to determine the coincidence of and pause duration in a coincidence circuit with pulse gaps of the two pulse trains (/ „; /,) are compared with one another. According to the log directed is. gical state of the coincidence circuit are of