CN100370262C - Cable Core Current Detector - Google Patents

Abstract

The present invention relates to a cable core current detector, particularly to a non-contact type pulse current detector which can dynamically measure cable core current at real time. At present, a frequently used method comprises the steps that an outer shielding layer of the cable is stripped, or a leading wire is used for leading out the core current; then a detector is used for measurement; but, under the conditions of a cable which is welded with cable adapter heads at both ends and installed in a device, current signals in the cable are difficult to measure. The present invention has a cylindrical embedded type structure; the axle center is a central conducting wire; inner cores of standard cable adapter seats are connected with both ends of the central conducting wire; the outer layer is a metal shielding shell connected with an outer shell of a cable seat; the measurement signal of the detector is positioned in a middle position and is transversely led out by a standard cable seat. Thus, the present invention is a cable core current detector having the advantages of skillful structure, convenient operation and high sensitivity.

Description

The cable core current probe

One, technical field:

The present invention relates to a kind of cable core current probe; Be specifically a kind of can be in real time, the contactless pulse current detector of heart yearn electric current on the kinetic measurement cable.

Two, background technology:

In scientific research and real work, need sometimes to measure, at present to being connected on the cable in the circuit electric current in the heart yearn, the method of using always is with the strip off of cable external shielding layer, perhaps use lead-in wire, the heart yearn electric current is extracted, measure with detector again; But be welded with the cable adapter, be installed under the situation in the device for two ends, just be not easy to measure the current signal in the cable.

Three, summary of the invention:

The purpose of this invention is to provide a kind of easy to use, measure cable core current probe accurately.

For achieving the above object, the technical solution used in the present invention is:

A kind of cable core current probe, its special character is: described cable core current probe comprises metal shielding 1, center conductor 5, heart yearn current sensor 4, the first cable adapter 2, the second cable adapter 3, cable block 6, insulator 7; Described cable core current probe is arranged in the metal shielding 1 that is full of insulator, and the two ends of the center conductor 5 of cable core current probe connect the first cable adapter 2 and the second cable adapter 3 respectively; Around center conductor 5 heart yearn current sensor 4 is set, heart yearn current sensor 4 is laterally drawn measurement signal line by cable block 6.

Above-mentioned heart yearn current sensor 4 is a Rogowsky coil, and it adopts magnetic material is to measure bobbin.

Above-mentioned heart yearn current sensor 4 is positioned at the centre position of center conductor 5.

Above-mentioned metal shielding 1 is connected with the shell of the first cable adapter 2, the second cable adapter 3.

Above-mentioned insulator 7 is a nylon material.

The measurement coil of above-mentioned heart yearn current sensor 4 is an enameled wire, 0.5 millimeter of linear diameter, the number of turns 15.

Above-mentioned magnetic material is the nickel Zinc material.

The present invention is with respect to prior art, and its advantage is as follows:

1, delicate structure, easy to use: as, can be connected with cable easily because there is the cable adapter at two ends of the present invention, it is middle with device perhaps to be connected cable, center conductor and cable core are connected, the screen layer of outer layer metal shielding case stube cable, the operate as normal that does not influence cable connects.

2, performance parameters is good: detector frequency spectrum of the present invention can widely reach 140MHz, low frequency can arrive 3Hz, measurement range is wide, current amplitude can be ten to hundreds of amperes, pulse rise time is less than 5 nanoseconds, pulse width can arrive 10 microseconds, and sensitivity is enough to satisfy pulse power experiment needs greater than 3.5V/A; In addition, be proportional relation between signal that measures and the heart yearn current waveform, convenient reading need not be carried out data processing again.

3, state of the present invention is independent, and tested loop is not had influence: because the signal measurement part is carried out physical isolation with measured heart yearn electric current, do not have getting in touch of electricity with tested loop, can not influence the state of measured heart yearn electric current.

4, heart yearn current sensor of the present invention is a Rogowsky coil, be placed in around the center conductor, use magnetic material as measuring bobbin, the measuring-signal outlet laterally places the detector middle part, carry out electrical isolation with detector center conductor, shielding case and isolate, thereby measure accurately.

Four, description of drawings:

Fig. 1 is a structural representation of the present invention;

Fig. 2 is that current probe of the present invention is demarcated connection diagram;

Fig. 3 is that current probe of the present invention is demarcated high frequency response figure;

Fig. 4 is that current probe of the present invention is demarcated LF-response figure.

Five, specific embodiment:

Referring to Fig. 1, the present invention includes metal shielding 1, center conductor 5, heart yearn current sensor 4, the first cable adapters 2, the second cable adapters 3, cable block 6, insulator 7; The setting of described cable core flux detector is full of the metal shielding 1 of insulator interior, described insulator 7 adopts nylon material, and the two ends of the center conductor 5 of cable core flux detector connect the first cable adapter 2 respectively, the second cable adapter 3, thereby it can directly be connected on the adapter of cableport, do not influence the connection of cable in device, measure the current signal on the cable core easily; And metal shielding 1 is connected with the shell of the first cable adapter 2, the second cable adapter 3, realizes shielding action.Current signal can directly be connected to 50 ohm of coupling cables and observe waveform on the oscillograph.And the shell of metal shielding 1 and the first cable adapter, 2, the second cable adapters 3 connects, and makes the screen layer of outer layer metal shielding case 1 stube cable, realizes the shielding of cable core flux detector.

The sensor that the present invention measures pulse current is a heart yearn current sensor 4, and promptly Rogowsky coil adopts magnetic material as measuring bobbin, is arranged on the centre position of center conductor 5; Its ultimate principle is electromagnetic induction principle and total current principle: any time-varying current is always followed a mM disodium hydrogen phosphate, if there is a closing coil to place around electric current, on coil, will produce induction electromotive force so, according to the coil parameter difference, this voltage becomes differential or proportional relation with the source current relationship.Promptly when the induction reactance of detector much larger than its pull-up resistor (wL＞＞R) during value, the voltage of measurement and original signal are proportional relation; And when the induction reactance of detector much smaller than its pull-up resistor value (wL＜＜R) time, the voltage of measurement is the differential of original signal.

Specific embodiment:

The parameter of detector is among the present invention:

W=0.01 rice; r ₂=0.023 meter; r ₁=0.01 meter; The n=15 circle; u _r=2000; u ₀=4 π * 10 ^-7By the inductance formula: $L=\frac{w{u}_0{u}_r{n}^2}{2\mathrm{\π}}\ln (r_2/r_1)$

Obtain: L=7.496 * 10 ^-4H

Above-mentioned parameter w coil width, r ₁Be coil outer diameter, r ₂Be internal coil diameter, n is the number of turns of coil, u _rBe relative permeability, u ₀Be permeability of vacuum;

Be easy to satisfy wL＞＞condition of R, the proportional relation of measuring-signal and original signal in this detector thus.

Heart yearn current sensor of the present invention is a Rogowsky coil, be placed in around the center conductor, use magnetic material as measuring bobbin, its magnetic material is the nickel Zinc material, heart yearn current sensor 4 is laterally drawn measurement signal line by cable block 6, the measuring-signal outlet laterally places the detector middle part, carries out electrical isolation with detector center conductor, shielding case and isolates, thereby measure accurately.

Referring to Fig. 2, Fig. 3, Fig. 4, Fig. 2 demarcates synoptic diagram to detector, the signal source output amplitude is 50 volts a pulse signal, is connected on 50 ohm load through behind the detector, and so measured electric current is 1 ampere, use the measuring-signal of oscillograph monitoring detector, its amplitude equals this detector sensitivity.Reference source signal and measuring-signal can obtain the parameter of detector sensitivity, response spectrum.

Fig. 3 is a caliper brake pulse current detector high frequency target standing wave shape.Fig. 4 is a caliper brake pulse current detector low frequency target standing wave shape.

The sense circuit model is R, L, C loop,

Demarcate for high frequency, if the input signal rising edge is t ₁, detector measurement waveform rising edge is t ₂, think that so the detector response time itself is:

$t_0=\sqrt{t_2^2-t_1^2}$

Its response frequency upper limit computing formula is

f _H＝0.35/t ₀

For low-frequency calibration, when input signal was square-wave signal, detector measurement obtained a square wave that flat-top decline is arranged, and its lower-frequency limit computing formula is:

$f_L=\frac{\mathrm{\δ}}{2\mathrm{\π}{v}_s{t}_p}$

Wherein: Vs is the amplitude that measures square wave, unit: volt;

Tp is a square width, unit: second;

δ be square wave in the tp width by the Vs decline scope, unit: the volt;

Table 1 is a detector high frequency nominal data.Signal source is a nanosecond generator mercury cut-off.Source signal: amplitude: 1 ampere; Pulsewidth: 100 nanoseconds.

Table 1 detector high frequency nominal data

Label	Source signal		Measuring-signal:
						Rising edge (ns)	Rising edge (ns)	Amplitude (V)	High frequency (MHz)
2	1.3	3.6	3.4	104.25
					3	1.35	3.6	3.6	104.88
4	1.4	2.8	3.4	144.34
					5	1.3	1.6	3.3	375.24
6	1.45	4.5	3.48	82.15

Table 2 is detector low-frequency calibration data.Signal source is wide pulse signal source 214B).Source signal: amplitude: 1 ampere; Pulsewidth: 6 microseconds.

Table 2 detector low-frequency calibration data

Label	Measuring-signal:
					Amplitude (V)	Flat-top falls (V)	Low frequency frequency (KHz)
2	3.32	0.44	3.52
				3	3.58	0.62	4.6
4	3.4	0.4	3.14
				5	3.4	0.48	3.74
6	3.44	0.46	3.54

Detector sensitivity and the frequency range of table 3 for measuring.Can see that this detector sensitivity is higher, and spectral range is bigger, satisfies the needs aspect current measurement fully.

Table 3 detector sensitivity and frequency range.

Label	1#	2#	3#	4#	5#
						Sensitivity (V/m)	3.4	3.6	3.4	3.3	3.48
Frequency range (kHz～MHz)	3.52～104	4.6～104	3.14～144	3.74～375	3.540～82

Claims (7)

1. A cable core wire current detector, characterized in that: the cable core wire current detector includes a metal shielding shell (1), a central wire (5), a core wire current sensor (4), a first cable switch Connecting seat (2), second cable adapter seat (3), cable seat (6), insulator (7); the cable core wire current detector is set in the metal shielding case (1) filled with insulator, and the cable The two ends of the center wire (5) of the core wire current detector are respectively connected to the first cable adapter (2) and the second cable adapter (3); the core wire current sensor ( 4), the core wire current sensor (4) leads out the measurement signal line through the direction perpendicular to the center wire through the cable seat (6). 2 . The cable core wire current detector according to claim 1 , characterized in that: the core wire current sensor ( 4 ) is a Rogowski coil, which adopts magnetic material as the measuring winding skeleton. 3. The cable core wire current detector according to claim 1 or 2, characterized in that: the core wire current sensor (4) is located in the middle of the central wire (5). 4. The cable core wire current detector according to claim 3, characterized in that: the metal shielding shell (1) and the first cable adapter (2) and the second cable adapter (3) Shell connection. 5. The cable core wire current detector according to claim 4, characterized in that: said insulator (7) is nylon material. 6. The cable core wire current detector according to claim 4, characterized in that: the measuring coil of the core wire current sensor (4) is an enameled wire with a diameter of 0.5 mm and 15 turns. 7. The cable core wire current detector according to claim 4, characterized in that: said magnetic material is nickel-zinc material.

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