SU832488A1

SU832488A1 - Frequency-measuring device

Info

Publication number: SU832488A1
Application number: SU782620316A
Authority: SU
Inventors: Петр Антонович Кунцевич
Original assignee: Всесоюзное Научно-Производственное Объеди-Нение "Циклон"
Priority date: 1978-05-29
Filing date: 1978-05-29
Publication date: 1981-05-23

Description

1one

Изобретение относитс к импульсной технике.The invention relates to a pulse technique.

Известно устройство дл измерени частоты синусоидального напр жени , содержащее пороговое устройство,ключ дифференцирующую и интегрирующие цепи , детекторы, цифроаналогомлй преобразователь , индикатор, фазосдвигающие цепи i).A device for measuring the frequency of a sinusoidal voltage, containing a threshold device, a key differentiating and integrating circuits, detectors, a digital-to-analog converter, an indicator, phase-shifting circuits i), is known.

Недостатком данного устройства вл етс его сложность.The disadvantage of this device is its complexity.

Наиболее близким по технической сущности к предлагаемому вл етс устройство, содержащее частотно-избире1тельный элемент, вход которого соединён через диод с одной из фазныхцепей , трехфазной сети, логический элемент И, например диодный, один вход которого соединен с выходом частотно-избирательного элемента , а второй вход подключен ко вторичной обмотке трансформатора, причем обща шина устройста соединена с нейтралью трехфазной сети 02 Недостаток данного устройства - недостаточна точность.The closest in technical essence to the present invention is a device comprising a frequency-selective element, the input of which is connected via a diode to one of the phase circuits, a three-phase network, a logical element AND, for example, a diode one, one input of which is connected to the output of the frequency-selective element, and the second the input is connected to the secondary winding of the transformer, and the common bus of the device is connected to the neutral of the three-phase network 02 The disadvantage of this device is the lack of accuracy.

Цель изобретени - повышение точности .The purpose of the invention is to improve accuracy.

Поставленна цель достигаетс тем что в устройство, содержащее частотно-избиратёльный элемент, вход которого соединен через диод с одной из фазных цепей трехфазной сети, логический элемент И, например диодный, один вход которого соединен с выходом частотно-избирательного элемента , а второй вход подключен ко вторичной обмотке разделительного трансформатора , причем обща шина устрой0 ства соединена с нейтралью трехфазной сети,, частотно-.избирательный элемент выполнен в виде RC-моста, одна диагональ которого соединен с общей шиной и входом частотно-избирательно5 го элемента, а втора соединена через диод с первичной обмоткой согласующего трансформатора этого элемента , вторична обмотка разделительного трансформатора соединена со второй The goal is achieved by the fact that in a device containing a frequency-selective element, the input of which is connected via a diode to one of the phase circuits of a three-phase network, a logical element AND, for example, a diode one, whose input is connected to the output of the frequency-selective element, and the second input is connected to the secondary winding of the isolation transformer, and the common bus of the device is connected to the neutral of the three-phase network, the frequency-selective element is made in the form of an RC bridge, one diagonal of which is connected to the common bus and the frequency-selective element, and the second is connected through a diode to the primary winding of the matching transformer of this element, the secondary winding of the isolation transformer is connected to the second

0 фазной цепью трехфазной сети, а выход устройства через резистор соединен со входом частотно-избирательного элемента.0 phase circuit of a three-phase network, and the output of the device through a resistor is connected to the input of the frequency-selective element.

На- чертеже представлена принципи-: The drawing shows the principle:

5 альна электрическа схема описывае-мого устройства.5 is an electrical circuit of the device described.

Устройство содержит частотно-избирательный элемент 1, состо щий из RC-моста 2, из конденсаторов 3, 4 The device contains a frequency-selective element 1, consisting of an RC bridge 2, of capacitors 3, 4

Claims

0 and resistors 5, 6, transformer 7, the primary winding 8 of which is connected via diode 9 with a diagonal RC-Mo and diode element I 10 from diodes 11, 12 and resistors 13, 14 first phase circuit 15 isolation transformer 16, secondary winding which, via a resistor 17, is connected to a second phase circuit 18, an input resistor 19 and a diode 20 are connected to the first phase circuit 15, a four-wire transmission line 21 of a three-phase alternating voltage .. A common bus 22 of the frequency relay is connected to a neutral line 21. The principle of operation of the device is the following. The principle of operation of the frequency-selective device is based on the use of the RC-bridge property to store the delay time of the output signal t relative to the input (in this case, relative to the moment of crossing it). If the opposite shoulders of an RC bridge are equal, this delay time is related to its constant time C with a ratio, which means that it does not depend on the amplitude of the voltage of the input signal. In the case of a three-phase voltage supply, the beginning of the charge of the capacitors 3, 4 of the RC bridge 2 corresponds to the arrival time of the negative half-wave voltage of phase A. When the negative half-wave of the phase A voltage arrives at the RC bridge 2 input, the capacitors 3, 4 begin to charge through the corresponding resistors 5, 6. At the same time, there is no current in the winding 8 of the transformer 7, since the diode 9 turns on counter to the voltage on the diagonal of the RC bridge 2. In this state, the RC-MOCT 2 is at the moment of its equilibration, after which the current in the winding 8 transformer 7 will quickly change to a value determined by the resistance value of the resistor 5, 6 and the instantaneous value. The voltage at the input of the RC bridge 2. Since the primary winding 8 of the transformer 7 is connected to the current source, what is it for? 2, then a voltage pulse is formed on the secondary winding of the transformer 7, amplitude L1a, which is proportional to the rate of current change in winding 8, and the top of this pulse corresponds to the balancing moment of the RC bridge 2. This negative polarity pulse delayed by t TV 2 relative to the initial .fazy input signal (voltage phase A) is applied to one input of the AND element 10 at its other input receives pulses from the transformer 16, the last is based on the use of the properties of the peak transformer. On the secondary winding of the transformer 16, pulses of both polarities are formed, the vertices of which correspond exactly to the zero-crossing moment of the input signal of the phase voltage B. Element I 10 uses pulses of negative polarity corresponding to the zero-phase transition of the input signal (phase voltage B when changing its polarity from positive to negative and delayed at the time m t relative to the initial phase of the input signal (voltage of phase A). Thus, the output of the And 10 element can appear l only if the condition of frequency is fulfilled, which is valid only for a certain frequency range of the input signal to which the device is tuned. The selectivity of the device is determined by the sum of the durations of the pulses arriving at both inputs of element I. The invention formula for detecting a frequency deviation in three phase the power grid network containing a frequency-selective element, the input of which is connected through a diode to one of the phase circuits of the three-phase network, the logical element AND, for example, a diode one, It is connected to the output of the frequency selective element, and the second input is connected to the secondary winding of an isolation transformer, the common bus of the device connected to the neutral of a three-phase network, characterized in that, in order to improve the accuracy, the frequency-selective element is designed as an RC bridge, one diagonal of which is connected to the common bus and the input of the frequency-selective element, and the second through the diode - to the primary winding of the output according to the transformer of this element, and the secondary winding is separator About the transformer is connected to the second phase circuit of the three-phase network, and the Bbixoji device through a resistor is connected to the input of the frequency-selective element. Sources of information taken into account in the examination 1. USSR author's certificate number 524138, cl. G 01 R 23/00, 30.04.75.

2. Authors certificate of the USSR 496504, cl. G 01 I 23/00, 05.02.74 ..

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