RU2093838C1 - Current measuring transducer - Google Patents

Abstract

FIELD: measurement technology; current measurements in power meters. SUBSTANCE: transducer has current transformer, linearly varying voltage generator, detectors of positive and negative pulses, and flip-flop. EFFECT: improved measurement accuracy. 2 dwg

Description

 The invention relates to measuring equipment and can be used to measure current, as well as in power meters of the amount of electrical energy.

 Widely known measuring scale current converters such as current transformers. The disadvantages of these converters include the conversion error, increasing with decreasing frequency of the measured current. Other disadvantages of the measuring current transformer are significant weight and dimensions, also increasing with decreasing frequency of the measured current and the inability to work on direct current.

 Known measuring current transducer [1] a prototype of the invention, containing a measuring transformer included by the primary winding in the circuit of the measured current, the second measuring current transformer, two differential amplifiers, two-terminal devices in the form of a resistor and capacitor. The prototype has the advantage over the measuring transformer that its error does not increase with decreasing frequency of the measured current and it can operate on direct current. However, its error due to the use of differential amplifiers and bipolar in the measuring path, an additional measuring transformer is quite large. The same can be said about its weight and dimensions.

 The aim of the invention is to remedy these disadvantages of the prototype.

 This goal is achieved by the fact that the measuring current transducer containing the current transformer, the primary winding of which is included in the circuit of the measured current, additionally contains a periodically ramp generator, a positive detector, a negative pulse detector, an RS trigger, and the periodically linear alternating current generator is loaded on the secondary winding of the transformer connected to the combined inputs of the detectors of positive and negative pulses, the outputs of which are separately connected They are connected with the R- and S-inputs of the trigger, the output of which serves as the output of the measuring signal, the pulse phase of the converter.

Figure 1 presents a block diagram of a measuring current transducer according to the invention;
figure 2 shows the timing diagrams of the Converter in figure 1.

 The measuring current transformer shown in figure 1, contains a current transformer 1, the primary winding of which is included in the circuit of the measured current and differs from the prototype in that it additionally contains a generator 2 of a periodically ramp current, detector 3 positive, detector 4 negative pulses, RS- trigger 5, and the generator 2 of a periodically linear variable current is loaded on the secondary winding of the transformer 2, connected to the combined inputs of the detectors 3 and 4 of positive and negative pulses, output The odes of which are separately connected to the R- and S-inputs of trigger 5, the output of which serves as the output of the measuring signal of the pulse phase of the converter.

 The operation of the measuring Converter is illustrated by the timing diagrams in figure 2.

Generator 2 provides the flow in the secondary winding of transformer 1 of current I _op periodically linearly varying from -I _max to + I _max over time T. For transformer 1, the condition is met: H _m • 1 <2I _max • W ₂ , where H _m - the magnetic field in the core of the transformer 1, corresponding to the state of saturation, l is the length of the average power line of the core, W ₂ is the number of turns of the secondary winding of the transformer 1.

Under this condition, the transformer 1 under the influence of the current of the generator 2, most of the period T will be in a state of saturation only twice leaving it and magnetizing under the condition: I _ISM • W ₁ = I _op • W ₂ .

The magnetization reversal of the core of the transformer 1 causes the appearance of pulses on its secondary winding, the polarity of which depends on the direction of magnetization reversal. These pulses converted by detectors of 3 and 4 pulses into normalized logic signals trigger an RS-trigger, which generates the output signal of the converter, the phase of the pulses, which is proportional to the measured current:
Φ = (1 + I _meas. X W ₁ / I _op x W ₂ ).
Using the proposed measuring transducer will improve the accuracy of measuring current, especially at low frequency and direct current, reduce the size and weight of the measuring devices.

Claims (1)

 A measuring current transducer comprising a measuring current transformer included by the primary winding in the measured current circuit, characterized in that the generator of a periodically ramp current is connected by an output to the terminals of the secondary winding of the measuring current transformer and to the inputs of the detectors of positive and negative voltage pulses, the outputs of which are connected respectively to R- and S-inputs of the RS-flip-flop, the output of which is the information output of the measuring transducer.

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