RU82863U1 - SENSOR CURRENT THRESHOLD QUICK - Google Patents

Abstract

A fast-acting threshold current sensor containing a resistive element, a signal comparison circuit, a signal output circuit, a transformer, a converter and a sensor, characterized in that the signal that the current threshold is exceeded in the measured circuit is transmitted through the transformer by increasing the power consumption of the secondary circuits located on the circuit potential with a measured current, which is fixed in the primary circuits located on the potential of the signal circuits.

Description

The utility model relates to electrical measuring equipment, namely, to power current sensors.

Galvanically isolated current sensors between the measured current circuit and the alarm circuits are known from the following sources:

1. Automatic high-speed switches for trolley buses / E.Sh. Muradov, VV Shipitsyn, R.E.Seredko. - Yekaterinburg: Polygraphist, 2005., p. 127-136;

2. Automatic high-speed switches for trams / E.Sh. Muradov, A.A. Gritsuk, A. V. Puzan. - Yekaterinburg: Polygraphist, 2006., p.197;

3. Patent for utility model “Current Sensor” RU No. 75753, 2008

Current sensors according to sources 1 and 2 contain a Hall sensor located in the context of the magnetic circuit, a signal processing circuit from the Hall sensor. When current flows through the cross section of the magnetic circuit, a magnetic field is induced in the magnetic circuit. When a magnetic field acts on the Hall sensor, a voltage is induced in it with a value proportional to the measured current. The voltage is supplied to the signal processing circuit, and if it exceeds or falls below the normalized current value, a sensor signal is output. The main isolation from high potential is the insulation between the bus with the measured current and the magnetic core with the sensor.

A disadvantage of the known current sensor is the low accuracy of current measurement due to the large number of transformations (through the magnetic field and the Hall effect), and the application for conversion

magnetic field into the measured voltage of the semiconductor element - the Hall Sensor, the conversion accuracy of which is highly dependent on its temperature.

The closest in technical essence to the patented current sensor threshold fast-acting is a current sensor by source 3. The current sensor by source 3 contains a resistive element, an amplifier, an analog-to-digital converter, a separating transformer, a digital-to-analog converter, a power supply unit, a power transformer. The output of the resistive element is connected to the amplifier, its output to the analog-to-digital converter, the output of the converter to the primary winding of the isolation transformer, which serves as galvanic isolation on the signal channel, the secondary winding of the isolation transformer is connected to the digital-to-analog converter. A digital-to-digital signal conversion circuit is introduced to transmit information through a transformer with minimal distortion of the original signal. The amplifier and analog-to-digital converter receive electricity through a power transformer, which serves as galvanic isolation on the power channel. The isolation transformer and the power transformer must be isolated between the windings, designed for the total voltage between the circuit with the measured current and the circuits of the electronic components that make the measurement. A disadvantage of the known current sensor with a sufficiently high measurement accuracy is its non-performance, due to the fact that through an isolating transformer it will be possible to pass an alternating current with a frequency of no higher than 10 kHz, which when transmitting a 16-bit signal (with high measurement accuracy) leads to a signal delay of the order of 0, 45 ms, which is unacceptable for many sensor applications. The sensor is quite complicated due to the presence in its design of 2 transformers - a separating and

power transformer. In addition, to obtain a threshold signal, such a sensor must be equipped with a comparison device, which will further complicate its design.

A useful model solves the problem of creating a threshold fast-acting current sensor, which allows to measure the current in the circuit with high accuracy and to signal without exceeding a predetermined current level, while ensuring complete galvanic isolation of the high-voltage circuit from the ground potential with just one transformer.

The technical result, which is achieved by the utility model, consists in increasing the accuracy of current measurement and reducing the delay time of the signal while maintaining complete galvanic isolation between the circuit with the measured current and the signaling circuits.

This is achieved by the fact that a resistive element having high measurement accuracy is installed in the high voltage current circuit with a signal comparison and output circuit. The resistive element converts the amount of current flowing through the high voltage circuit into a proportional voltage value. The comparison circuit compares the signal from the resistive element with the value specified in the circuit. The comparison circuit and the signal transmission circuit are powered by a transformer, which serves as the galvanic isolation of the potential of the high voltage circuit from the ground potential. If the signal from the primary converter is reduced or exceeded below or above the value set in the comparison circuit, the comparison circuit transmits a signal to the signal output circuit. The signal output circuit at the same time significantly reduces its internal resistance along the power circuit. The current consumed from the transformer increases sharply, but the current consumed by the primary winding of the transformer also increases. A converter that transfers energy to power a transformer contains

It includes a sensor that responds to an excess of current in the power circuit, which, in case of excess of the current supply, gives a signal in the alarm circuit.

The introduction of a circuit for comparing and issuing a signal, a converter, and a current sensor made it possible to execute a communication channel through a transformer providing power and galvanic isolation, and to obtain a high transmission rate of information about a decrease or excess of the current threshold in the measured circuit. Regarding speed, it can be explained that when applied to power and transmit an AC signal with a frequency of 10 kHz, the load increase will be monitored in the primary winding after half a period, which will correspond to a 0.05 ms signal transmission delay.

The utility model is illustrated by the drawing, where the figure shows a block diagram of a patented threshold high-speed current sensor.

The high-speed current sensor contains a resistive element 1, which has high measurement accuracy and thermal stability, a comparison circuit 2 with a preset control signal level, a signal output circuit 3 with an integrated load, a transformer 4, a transducer 5 with a sensor 6.

The current threshold threshold sensor operates as follows. The resistive element 1 converts the amount of current flowing in the high voltage circuit into a proportional voltage suitable for measurement by electronic components. The resulting voltage is transmitted to the comparison circuit 2, in which the voltage is compared with the control. When the voltage value corresponds to the normal current value in the measured circuit, the comparison circuit does not transmit any further signals. The comparison circuit 2 receives power from the secondary winding of the transformer 4. The same winding receives power from the secondary winding

signal. If the value of the monitored signal from the resistive element 1 decreases or exceeds below or above the control value preset in the comparison circuit 2, the signal is transmitted to the signal issuing circuit 3. The signal issuing circuit 3, when a signal is applied to it, connects an additional load to the secondary winding of transformer 4. The current of the secondary winding of the transformer 4 increases, which entails an increase in the current in the primary winding. A converter 5 and sensor 6 are included in the power supply circuit of the primary winding of transformer 4. Converter 5 is designed to convert the supply voltage of the entire sensor to an alternating voltage for supplying the primary winding of transformer 4, and sensor 6 is required to record the current consumption of the primary winding of transformer 4 and provide a signal when exceeding its level. Therefore, with increasing current consumption on the secondary side, the additional load from the signal 3 output circuit, sensor 6 will detect excess consumption and will provide information on the sensor operation in the measurement circuit.

Thus, a simple threshold current sensor was created to signal the excess or decrease of the current strength above or below the set with high accuracy measurement, with high speed, in circuits with any voltage.

Claims (1)

A fast-acting threshold current sensor containing a resistive element, a signal comparison circuit, a signal output circuit, a transformer, a converter and a sensor, characterized in that the signal that the current threshold is exceeded in the measured circuit is transmitted through the transformer by increasing the power consumption of the secondary circuits located on the circuit potential with a measured current, which is fixed in the primary circuits located on the potential of the signal circuits.