SU1499244A1 - Normalizing transducer of signals of a.c. voltage and current - Google Patents

Abstract

The invention relates to information-measuring technology for matching and galvanically isolating monitored low-frequency alternating voltage and current circuits, such as electrical networks, to the inputs of control devices. The aim of the invention is to improve the accuracy of conversion and the expansion of the dynamic range. For this, the amplifier 9 is designed as a voltage follower, its output is connected to the end of the compensating winding 10 of the current transformer 3, the beginning of which is connected to the input of the repeater 9 and the end of the secondary winding 6. The input current flowing through the limiting resistor 1, the primary winding 2 and the input terminals 4 and 5, in the core of the transformer 3, creates a magnetic flux which is compensated by the current generated by the current in the secondary winding 6 and the feedback resistor 8. The losses in the windings of the transformer 3 and its core are compensated for by the current of the repeater 9 through the winding 10. In case the input signal is voltage, the resistor 1 is bridged by jumper 11. The useful signal is removed from the output terminal 7. 1 Il.

Description

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The invention relates to an information-measuring technique and can be used for matching and galvanic separation of controlled low-frequency circuits of alternating voltage and current with the inputs of electric power control devices (active and reactive power, phase shift between signals, power factor

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The aim of the invention is to improve the accuracy of conversion of monitored signals and the expansion of the dynamic range.

The drawing shows a diagram of the normalizing measuring transducer,

The normalizing measuring converter contains a limiting resistor 1 connected in series with the primary winding 2 of the current transformer 3 and the input terminals 4 and 5, the beginning of the secondary winding 6 is connected to the output terminal 7 and grounded through the feedback resistor 8, the end of the secondary winding 6 is connected to the input repeater 9 voltage and the beginning of the compensating winding 10, the end of which is connected to the output of the repeater 9 voltage. In the case of a current conversion, the limiting resistor 1 is bridged by a jumper 11,

The normalizing measuring converter works as follows.

The input current i flows through the primary winding 2 of the current transformer 3 and creates a magnetic flux p, which induces an emf in the secondary and compensating windings.

Claims (1)

In the secondary winding, a current Ij appears, which creates its own magnetic flux Pj, which closes through the same core of the current transformer 3, with F being opposed to F. The resulting flux φ f, which characterizes the losses in the core, and the windings of the current transformer 3 is compensated by the output current of the voltage follower 9 with a transmission coefficient equal to one, which creates a compensating flow. Since the output resistance of repeater 9 is small, the compensating winding 10 shunts the secondary winding 6 and the feedback resistor 8, therefore the EMF of the secondary winding 6 is zero. The formula of the invention The normalizing measuring transducer of alternating voltage and current signals, containing a limiting resistor, is connected in series with the input terminals of the device and the primary winding of the current transformer, the beginning of the secondary winding of the current transformer is connected to the output terminal of the device and through the feedback resistor is grounded; coupled to an amplifier input, characterized in that, in order to increase the accuracy of converting monitored signals and expand the dynamic range azone, vylolnen amplifier as a follower voltage, and its output is connected to the end of the compensating coil, which began kontso.m connected to the secondary winding.