CN201697960U - Lightning current sensor with iron core - Google Patents

Abstract

The utility model discloses a lightning current sensor with an iron core. It consists of iron core, insulating sheath, induction coil, signal resistor, transient voltage suppressor, signal lead-out head, insulating protective layer and movable joint. The iron core is buried in the insulating sheath cylinder; the induction coil is wound on the outer surface of the insulating sheath, and its end passes through the insulating sheath cylinder and the iron core; the signal resistor is connected in parallel with the transient voltage suppressor and then connected to the head of the induction coil Both ends; the insulating protective layer encapsulates the above-mentioned iron core, insulating sheath, induction coil, signal resistor, and transient voltage suppressor in its cavity, bends it into a ring shape and connects it into a closed ring through a movable joint; the signal lead-out head Fixed on the movable joint. The advantages of the utility model are: 1. The range of current to be measured is allowed to be large, the output signal is stable and linear, and the measurement accuracy can meet the requirements of related measurements; 2. The device is equipped with movable joints, which is easy to install and use; 3. The device is small in size , light in weight, simple in structure and low in cost.

Description

Lightning current sensor with iron core

technical field

The utility model relates to a current measuring device, in particular to a lightning current sensor with an iron core, which is suitable for the measurement of high frequency or pulse large current.

Background technique

At present, there are two main types of sensors used for measuring pulsed large currents, namely resistive shunts and Rogowski coils.

Resistive shunts are only suitable for measuring currents below 10kA; for currents above 10kA, although multiple resistive shunts can be used in parallel for measurement, the volume of the entire device will be very large and cumbersome after parallel connection. Although the accuracy of industrial resistance shunts is usually rated as 0.5, when they are used to measure large currents, the resistance value will change due to their own temperature changes, which will seriously affect their measurement accuracy. At the same time, when a resistor shunt is used to measure a rapidly changing pulsed large current, the voltage at the potential output end of the shunt will time-shift due to the skin effect of the shunt. In addition, there are the following two defects when using a resistance shunt to measure lightning impulse currents: first, the primary circuit of the shunt must be disconnected and connected to the circuit under test during measurement, which brings a lot of inconvenience to installation and use; and The access of the shunt will also affect the electrical parameters of the measured current loop; secondly, because the primary circuit of the shunt is not electrically isolated from the secondary circuit, it is not suitable for computer-based relay protection and other metering equipment or control devices that contain computers. device.

Compared with the resistance shunt, the Rogowski coil itself has no direct electrical connection with the measured current loop, but realizes the measurement of large current through electromagnetic field coupling, so it has good electrical insulation with the tested loop. The Rogowski coil has a wide measurement frequency range (generally 0.1-100MHz, and a specially designed Rogowski coil can reach a bandwidth of 2000MHz), the rise time of the coil itself is small (such as on the order of nS), and the measurement accuracy is high (generally between 0.5% and 2%) The specially designed Rogowski coil can be better than 0.1%), easy to digital output, so as to realize digital measurement, networking and automation, and will not produce flammable, explosive and other dangers, and meet environmental protection requirements.

At present, the Rogowski coils used in China are mostly hollow Rogowski coils. The hollow Rogowski coil avoids the loss and nonlinear influence caused by the use of the iron core, but at this time the inductance in the loop is mainly provided by the coil, and the self-integration condition is not easy to satisfy, so the hollow Rogowski coil requires more coil turns. Larger volume.

Contents of the invention

The purpose of the utility model is to overcome the shortcomings of the existing hollow Rogowski coils and provide a lightning current sensor with an iron core for lightning current monitoring.

The utility model is in order to solve the technical scheme of the above-mentioned technical problem as follows:

Lightning current sensor with iron core, which is composed of insulating protective layer 1, movable joint 2, signal lead-out 3, iron core 4, insulating sheath 5, induction coil 6, signal resistor 7 and transient voltage suppressor 8; the sensor It is ring-shaped, the insulating protective layer 1 is an open annular tube, the insulating sheath 5 is cylindrical, and the signal resistor 7 is a metal film resistor; the position and connection relationship of each component are as follows:

The iron core 4 is buried in the insulating sheath 5 cylinder; the induction coil 6 is wound on the outer surface of the insulating sheath 5, and its end passes through the insulating sheath cylinder and the iron core; the signal resistor 7 is connected in parallel with the transient voltage suppressor 8 Connected to the first and last ends of the induction coil 6; the insulating protective layer 1 encapsulates the above-mentioned iron core 4, insulating sheath 5, induction coil 6, signal resistor 7, and transient voltage suppressor 8 in its cavity, and bends it into a ring shape And the movable joint 2 is connected to form a closed circle; the signal lead-out 3 is fixed on the movable joint 2 .

The above insulating protection layer 1 is an open ring pipe made of PPR material.

The utility model has the following advantages and positive effects:

1. The utility model is small in size, light in weight, simple in structure, low in cost, and designed with movable joints, which is easy to install and use.

2. The measurement range of the lightning impulse current of the utility model is 3kA～150kA; the output signal has good stability and linearity, the precision can meet the relevant measurement requirements, and the measurement error can be controlled within 3%; the self-inductance coefficient is large and the internal resistance is small And it is easy to realize the self-integrating structure.

3. The device of the utility model is equipped with a transient voltage suppressor, which can limit the output voltage and protect the precision components in the signal measurement electronic module.

4. The utility model itself does not need to install a metal shielding layer.

Description of drawings

Figure 1 is a schematic diagram of the appearance of the utility model with an iron core lightning current sensor;

Fig. 2 is a schematic diagram of the internal structure of the iron core type lightning current sensor of the present invention;

Figure 3 is a schematic diagram of the movable joint.

In the figure: insulation protection layer 1, movable joint 2, signal lead-out 3, iron core 4, insulation outer 5, induction coil 6, signal resistor 7, transient voltage suppressor 8.

Detailed ways

Using method and working principle of the present utility model are:

When working, the measured current-carrying conductor passes through the center of the lightning current sensor with iron core. According to the law of electromagnetic induction, the output voltage of the sensor has a differential relationship with the measured current. Therefore, in order to restore the measured current, the coil’s The output voltage is consistent with the actual phase of the primary current, and an integrator is added at the port to integrate the induced potential.

The utility model and the measured current-carrying conductor carry out accurate measurement of large current through magnetic field coupling, without the need of electrical connection with the measured current loop, so the isolation between high and low voltage can be realized.

The utility model selects the resistance sampling method for signal sampling, which is suitable for the measurement of high-frequency signals: when the frequency of the measured current is very high (such as lightning impulse current), its angular frequency ω is very large, and the inductance ωL of the sensor will be Very large, easy to meet the self-integration condition; the output voltage at both ends of the sampling resistor is proportional to the amplitude of the primary current, and the phase is the same, to achieve the purpose of measuring the input current by measuring the output voltage.

The signal resistor (7) adopts a metal film resistor, which has small self-inductance, stable resistance, and is basically not affected by changes in the measured current and ambient temperature; at the same time, it has sufficient heat capacity to prevent blowout; in addition, the signal resistor has Good shielding reduces the influence of the measured current loop and other stray magnetic fields on the resistance and inductance.

A transient voltage suppressor (8) is connected in parallel at both ends of the signal resistor (7). When the two poles of the transient voltage suppressor are subjected to a reverse transient high-energy impact, it can change the high impedance between its two poles into a low impedance within ^10-12 S order of magnitude, absorbing surges up to several thousand watts The power clamps the voltage between the two poles at a predetermined value, effectively protecting the precision components in the electronic circuit from being damaged by various surge pulses. The transient voltage suppressor in the utility model can select different parameters according to the voltage value to be clamped.

The utility model has good linearity during measurement, and its shielding and anti-disturbance measures meet the measurement requirements, so no metal shielding layer is required, so the utility model has a simple structure and low manufacturing cost.

The utility model selects the PPR material to make the insulating protective layer. Good PPR pipe, pipe fittings have the characteristics of corrosion resistance, waterproof junction, high temperature and high pressure resistance, long life, easy connection, etc. The flexibility of the pipe fittings makes the installation and construction of the device faster, safe and reliable, can shorten the construction period, and the construction cost is 60 less than that of copper pipes %, with superior economy.

Below in conjunction with accompanying drawing and embodiment the utility model is described in detail.

1. Overall

As shown in Figure 1, Figure 2, and Figure 3, the utility model includes an insulating protective layer 1, a movable joint 2, a signal lead-out 3, an iron core 4, an insulating sheath 5, an induction coil 6, a signal resistor 7, and a transient voltage suppression device 8.

Its location and connection relationship are:

The lightning current sensor with an iron core consists of an iron core 4 , an insulating sheath 5 , an induction coil 6 , and an insulating protective layer 1 from the inner layer to the outer layer.

The iron core 4 is buried in the insulating sheath 5 cylinder; the induction coil 6 is wound on the outer surface of the insulating sheath 5, and its end passes through the insulating sheath cylinder and the iron core; the signal resistor 7 is connected in parallel with the transient voltage suppressor 8 Connected to the first and last ends of the induction coil 6; the insulating protective layer 1 encapsulates the above-mentioned iron core 4, insulating sheath 5, induction coil 6, signal resistor 7, and transient voltage suppressor 8 in its cavity, and bends it into a ring shape And the movable joint 2 is connected to form a closed circle; the signal lead-out 3 is fixed on the movable joint 2 .

2. Functional components

1. Insulation protective layer 1

The function of the insulating protection layer 1 is device packaging and sensor shaping.

2. Active joint 2

The movable joint 2 is a rotatable movable joint made of PPR material.

Its function is to disconnect or connect the sensor for easy installation and use.

3. Signal header 3

The signal lead-out 3 is a common signal connector.

Its function is to lead out the voltage signal.

4. Core 4

Iron core 4 is made of several thin iron wires.

Its function is to increase the inductance, which is conducive to satisfying the self-integration condition and reducing the number of turns of the induction coil required.

5. Insulation sheath 5

The insulating sheath 5 is a cable sheath material whose cross section is a ring, and other rubber materials may also be used.

Its function is to support and insulate, to isolate the inner iron core 4 and the outer induction coil 6, and to support the induction coil 6.

6. Induction coil 6

The induction coil 6 is a multi-turn coil made of fine copper wire.

Its function is to realize the mutual conversion of electric energy and magnetic energy through the magnetic field generated by the measured current, and induce an electric potential in the coil.

7. Signal resistance 7

The signal resistor 7 is a metal film resistor whose first and last ends are connected to the first and last ends of the induction coil 6 .

Its function is to output measurement signals.

8. Transient voltage suppressor 8

The transient voltage suppressor 8 is a type of diode.

Its function is to limit the highest voltage output by the induction coil 6 .

3. Working principle

The lightning current sensor with an iron core proposed by the utility model includes an insulating protective layer 1, a movable joint 2, a signal lead-out 3, an iron core 4, an insulating sheath 5, an induction coil 6, a signal resistor 7, and a transient voltage suppressor 8.

When working, the lightning current sensor with iron core forms a closed loop. When the measured current-carrying conductor passes through the center of the lightning current sensor with iron core, the required measurement signal can be obtained from the signal lead-out end of the sensor.

Claims (2)

1. ribbon core formula lighting current sensor, it is characterized in that it is made up of insulating protective layer (1), active joint (2), signal leading-out end (3), iron core (4), insulation sheath (5), inductive coil (6), signal resistance (7) and Transient Voltage Suppressor (8); This sensor is an annular, and insulating protective layer (1) is the open annular pipe, and insulation sheath (5) is cylindric, and signal resistance (7) is a metalfilmresistor; Each component locations and annexation are as follows:

Iron core (4) is embedded in insulation sheath (5) cylinder; Inductive coil (6) is wound on insulation sheath (5) outside surface, and its end passes in the insulation sheath cylinder, between iron core; Signal resistance (7) be connected to inductive coil (6) head and end after Transient Voltage Suppressor (8) is in parallel; Insulating protective layer (1) is encapsulated in above-mentioned iron core (4), insulation sheath (5), inductive coil (6), signal resistance (7), Transient Voltage Suppressor (8) in its cavity, and looped-shaped bending also is unified into close ring by active joint (2); Signal leading-out end (3) is fixed on the active joint (2).

2. ribbon core formula lighting current sensor according to claim 1 is characterized in that, described insulating protective layer (1) is the open annular pipe that adopts the PPR material to make, and by active joint, can disconnect or connect sensor.

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