JPS5895266A - Hybrid current sensor for measuring intensity of alternating current current flowing through electric wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides primary electric power aS flowing through the 111 line of a power supply device.
An electronic device for controlling the alternating current in the wires of the power supply, comprising a secondary winding wound on a magnetic core OMK to generate a combined measured secondary signal with a value dependent on the strength of 1. Measurement and 4! The present invention relates to a current sensor for performing at least one of the following.

According to conventional comb devices, the sensor includes a conventional flow straightener. The secondary winding of this current transformer can generate power. Current transformers coupled to electronic devices generally have a large number of turns, especially
Given the limited overall dimensions of the current transformer, temperature increases occur in the current transformer that disturb the performance of electronic equipment in close proximity to the current transformer. The high manufacturing cost and large overall dimensions of such current transformers are disadvantages of conventional current transformers.

Other known magnetic type current sensors, or current sensors with an air gap magnetic circuit, include a secondary winding that induces an output voltage proportional to the derivative of the primary current. This output voltage is applied to the high input terminal integrated circuit.

Although this type of sensor does not produce a temperature rise in /at kC, it generally requires an auxiliary power supply to operate the integrated circuit to which it is coupled.

The object of the present invention is to overcome these drawbacks and provide an improved induced current sensor capable of generating a predetermined secondary power with low temperature rise and without the need for an auxiliary power source to power electronic devices. be.

According to the present invention, a load resistor R2 is connected to the output terminal of the secondary winding having a resistance value R1, at least one air gap with a predetermined length e is provided in the magnetic core CM, and the inductive sensor is a hybrid type, whose two-dog samurai constant t2 is the relation n2
/R(R1+R2) 'VC YoQ fixed time. R
is the magnetic resistance value of the magnetic core CM, and n is the number of turns of the secondary winding. The time constant t2 is 10 microseconds to 100 milliseconds. The bracket for the time constant t2 value is 0.5 to g of the magnetic core.
The total length of one or several voids of Q mm and about 10 to 1
000 ohm and the resistance value of the load resistor R2.

In accordance with a feature of the invention, the secondary winding of the no-wave nineted sensor cooperates with a frequency compensation circuit connected to the terminals of the load resistor R2 to generate the measured spectral image signal. The width of this signal is constant when the frequency f of the primary current 11 is configured around the compensation center frequency fo within a predetermined range. In the frequency compensation circuit, the frequency of the primary current X is a center frequency f.

It consists of a phase shifter that shifts the phase of the measured video signal with respect to the primary current Xl when

According to another feature of the invention, the measured signal of the compensation circuit is provided to an electronic processing device. This electronic processing device issues a trip command to the operating coil of the breaker when the signal exceeds a predetermined threshold.

This processing device is supplied with an uncompensated voltage 02 taken from across the terminals of the load resistor R2.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The hybrid current sensor 10 shown in FIG. 1 has a toroidal magnetic circuit CM. This magnetic circuit 4 is provided with one or several air gaps 12 having a total length e. The electric power supply circuit 14 of the AC power supply circuit network is traced back to the magnetic circuit CM. This electric wire 14 serves as a primary winding through which the controlled current 11 flows. A secondary winding 1M16 is wound around the magnetic circuit 4. The number of turns of this secondary winding is n, and its electrical resistance value is R1. A load resistance R8 is connected between the output terminals of the secondary winding string 16.
is connected. The two-dog constant t2 of this hybrid Senna is determined by the relationship n''/R (R1+R2), where R is the total magnetic resistance value of the magnetic circuit 4.

The secondary winding 16 produces an output current 2 representing a vector quantity. The magnitude of the vector and the phase shift angle ψ with respect to the primary current line I are shown in FIG. Figure 2 shows the magnitude of the vector and the phase shift angle ψ of this vector with respect to the primary current 11, and 2
It is a graph showing the relationship between the Inusamurai constant t2 and the frequency of the primary current generator 1. The magnitude represented by the ratio n12/11 changes between 0 and 1 as the time constant t2 increases. When the time constant t2 is greater than 100 milliseconds, the senna is a conventional current transformer. Further, when the time constant t2 is less than 10 microseconds, this sensor is a non-magnetic sensor. This hybrid sensor is of intermediate type. The cross section of the secondary winding of an inductive sensor is proportional to the product nI2. nI2
It should be noted in FIG. 2 that this sensor is a current transformer when is approximately equal to . In this case, the volume is the largest and the cost is the highest.

The time constant t2 is between 10 microseconds and 100 milliseconds.
The number of turns of the secondary winding of an Ibrid Senna is significantly less than the number of secondary turns of an equivalent current transformer. Alternatively, when the overall dimensions are determined, in a conventional current transformer and a no-brid sensor with the same primary current rating, it is the latter that will center the lowest temperature rise.

Therefore, in order to determine the value of the time constant t2, it is sufficient to select the resistance value R2 of the load resistor, the cross-sectional area 8 of the magnetic circuit CM, and the length e of the air gap.

According to a test conducted, the total length e of the void is 0.5~+
20 Iol, load resistance value R2 is 10 to 1000
It has been found that the ohm can be determined according to the strength of the rated current 11 flowing through the wire 14.

Figure 3 shows the sky from Figure 1! Instead of the toroidal magnetic circuit with 112, a rectangular magnetic circuit 4 with two air gaps 121L, 121) is shown. This magnetic circuit C
M is composed of two 0-shaped basic parts facing each other so as to form a window through which the wires 14 intersect. One secondary winding 16 is wound in this magnetic circuit CMK.

The sensor shown in FIG. 4 is the same as the sensor shown in FIG. 3 except that the secondary winding includes two coils 16a, 16b connected in series or in parallel.

The relative amount of the coil lfi&, 161) with respect to the air gap can be made indefinite. The hybrid shown in Figure 1.3
The characteristics of the sensor depend on the frequency of the current generator 1. In fact, the loss width and phase of the output voltage 02 across the terminals of the secondary winding 16 change with frequency. Therefore, a frequency compensation circuit 18 (FIG. 5) is connected to this hybrid sensor.

This frequency compensation circuit 18 has a series Re circuit connected in parallel to the load resistor R2. The video signal of the current 11 to be measured is the voltage Oc appearing across the terminals of the capacitor C.

The value of RC of the frequency compensation circuit 18 is determined by the following equation.

where fo is the compensation center frequency (e.g. 55 Hz
).

FIG. 6 shows a frequency compensation circuit 18 consisting of a series circuit connected in parallel to a load resistor R2. In this case, the video signal of the current 11 is the voltage oB appearing across the terminals of the resistor R.

Figure 7 shows the output voltage U2 when no frequency compensation is performed, the output voltage Oc when frequency compensation is performed, and the frequency of the current 11 when the time constant t2 and the strength of the current 11 are given at °C. It is a graph showing the relationship. Video voltage port. It will be seen from FIG. 7 that the amplitude of is approximately constant at the frequency of the current 11 within a predetermined range centered on the compensation center frequency fo. When the frequency of the current 11 is equal to the center frequency fo, the current 1 and the voltage Oc are in phase.

FIG. 8 is a wiring diagram illustrating an application of the compensated hybrid sensor shown in FIG. This hybrid sensor provides a combined secondary signal of measurement and power to a current control device or static trip unit of a circuit breaker in which one contact is inserted into the fusion 14. The input signal MOc provided by the compensation circuit 18 is provided to the electronic processing unit 22 via a first connection line 24 . The uncompensated voltage port 2 of the secondary winding 16 is supplied to the processing device 22 via a second connection line 26 and is used as a power source for the processing device 22 .

1! When an overload or short condition occurs on line 14 , processor 22 generates a trip command and applies the command to trip coil 28 . The trip coil 28 then activates the trip mechanism 30 to open the protective circuit breaker contact 20.

The frequency compensation circuit [8] of this hybrid sensor can of course have a configuration other than the above.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the toroidal current sensor of the present invention, and Fig. 2 shows the magnitude of the output current (solid line) and phase shift angle (dashed line), and the quadratic time constant of the sensor shown in Fig. 1. When the frequency of the primary current is 50 Hz, the relationship between .4. An equivalent circuit diagram showing a bulb equipped with a frequency compensation circuit of the sensor shown in Figure 6. Figure 6 is a circuit diagram showing another example of the frequency compensation circuit.
The figure is a graph showing the relationship between the output voltage of the current sensor and the frequency of the primary current with and without frequency compensation. FIG. 2 is a wiring diagram showing an example of application of a hot-cup circuit breaker to an electronic device. 10... Current sensor, 16... Secondary winding, 18...
... Frequency compensation circuit, CM... Magnetic circuit ◎ Representative Kiyoshi Inomata 10ys joornsFig,
2 ” F'ig, 7 dan 1g8 -36;

Claims (1)

[Claims] (1) A magnetic core that surrounds an electric wire with a gap of a predetermined length and has a magnetic resistance value of R, and that generates a secondary signal related to the strength of the current flowing through the electric wire. a secondary winding wound n times around the magnetic core and having an electrical resistance value of R1; and a load resistor R2 connected to a terminal of the secondary winding, defined by the formula n/R(R1+12). and a second time constant t between 10 microseconds and 100 milliseconds
2. A hybrid current sensor for measuring the strength of alternating current that can weave electric wires. (2. The hybrid current sensor according to claim 1, characterized in that the length of the air gap is 0.5 to 20 - and the load resistance value R2 is 10 to 1000 ohms. Hybrid current sensor. (3) A hybrid current sensor according to claim 2, which is connected to the terminal of the load resistor R2 and has a width almost independent of the frequency fo of the alternating current. A hybrid current sensor characterized by having a frequency compensation circuit that generates an output signal. (4) The hybrid current sensor according to claim 3, wherein the frequency compensation circuit has a time constant of 17 (2π
fo) a resistor in series with a time constant approximately equal to 2tg -
A hybrid current sensor characterized by comprising a capacitor circuit. (5) A hybrid current sensor according to claim 3, wherein the frequency compensation circuit includes a series inductance-resistance circuit that produces an output signal at a terminal of a resistor. sensor. (6) a contact element for an electrical conductor, a circuit breaker, a transformer for the electrical conductor, a load resistor, and a solid state interrupt initiator, the circuit breaker being configured to The transformer includes a magnetic core having a magnetic resistance value and a gap of a predetermined length; A secondary winding is wound n times, the electrical resistance of the secondary winding is R1, the conductor excites the magnetic core, and the electrical resistance of the load resistor is R2, connected to the terminals of the secondary winding, the solid state interrupt initiator is connected to the output terminal of the load resistor to provide a disconnection signal to the circuit breaker when a fault condition occurs; is the relation n2/R (R1 + R2
), and is defined by 10 microseconds or more.
A circuit protection device that detects a fault condition in a power supply circuit that has a conductor that is specifically designed to last for 100 milliseconds. (7) The circuit protection device according to claim 6, wherein the length of the air gap is 0.5 to 20 mm, and the resistance value R2 of the load resistor is 10 to 1000 ohms. Characteristic circuit protection device. (8) The circuit protection device according to claim 7, comprising a frequency compensation circuit having a resistance-capacitance circuit or an inductance-resistance circuit connected to a terminal of the load resistor, The signal input terminal of the device is a resistor.
A circuit protection device, characterized in that it is connected to a terminal of a capacitor of a capacitive circuit or a terminal of a resistor of an inductance-resistance circuit, and a power input terminal of the solid state interrupt initiator is connected to a terminal of a load resistor.