Current transformer sensing head and current transformer
The utility model is related to a kind of current transformer sensing head and current transformer, is mainly used in intelligent electric meter row
The current measurement of industry.
At present, the current measurement circuit of intelligent electric energy meter industry, generally uses manganese copper diverter and electromagnetic type Current Mutual Inductance
Device.Current transformer is according to electromagnetic induction principle.As shown in figure 1, current transformer is the iron core and winding group by closing
Into its first winding number of turn seldom, is gone here and there in the circuit for the electric current for needing to measure, therefore it often has whole electric currents of circuit
Flow through, secondary winding turn ratio is more, is serially connected in measuring instrumentss and protective loop, current transformer operationally, its two
Minor loop is to close all the time, therefore measuring instrumentss and the impedance very little of protective loop series coil, the work of current transformer
The close short circuit of state.The advantage of transformer is that the linearity is good, and stability is high, and the degree of accuracy is particularly suitable for little with temperature change
The measurement of degree of precision (0.5S grades).
Reference edge using the current sampling of the electric energy meter of current transformer is connected in secondary side with zero line, therefore primary side
It is to isolate (see Fig. 2) with voltage circuit that electric current input, which is, and therefore, the reference edge of computation chip can be zero line N, is so measured
The voltage difference of multiple analog input ends of chip will be controlled in below 2V, in the permission model of common below the 5V operating voltages of chip
In enclosing.Voltage and the cut-in method being galvanically isolated, are particularly suitable for the application scenario of requirement two or more current loop measurement, such as two
Phase table, phase three-wire three table and three-phase and four-line table etc..
The shortcoming of transformer is：Volume is big, cost is high, anti-overload ability is weak, and the frequency range of measurable signal is general not
It can not be opened a way more than 2.5kHz, especially secondary side current measuring loop, otherwise can produce high voltage and damage measurement electricity
The content of the invention
The purpose of this utility model is to overcome above-mentioned problem that there is provided a kind of small volume, lightweight, cost are low
Current transformer sensing head and current transformer.
The purpose of this utility model is completed by following technical solution,
Current transformer sensing head, the sensing head is an air core solenoid formed using wire uniform winding, should
Solenoid output end connects current sampling circuit.
The solenoidal internal diameter is 0.5-1.5mm, and the winding number of turn is 1-10 circles.
The solenoid is fixed on embedded mode on the pcb board where the current sampling circuit.
The solenoidal height is less than or equal to the thickness of pcb board.
A kind of current transformer, including：
Foregoing sensing head；
Flow guide bar, passes through C-shaped yoke, two ends connect live wire end of incoming cables and live wire respectively by the bottom of C-shaped yoke C-channel
C-shaped yoke, the sensing head is inserted by the openend of C-shaped yoke, makes C-shaped yoke that the sensing is completely covered
It is inserted with the openend of the C-shaped yoke and inserts C with its opening direction identical C-shaped insulating trip, the sensing head
The openend of shape insulating trip, makes C-shaped yoke and C-shaped insulating trip that the sensing head is completely covered；The flow guide bar from C-shaped yoke and
C-shaped insulating trip, which is enclosed in cavity, to be passed through.
The flow guide bar includes order and is connected to form the end of incoming cables linkage section of U-shaped, sensing section, leading-out terminal linkage section；Wherein
End of incoming cables linkage section connection live wire end of incoming cables, leading-out terminal linkage section connection live wire leading-out terminal, sensing section passes through the C-shaped yoke,
So that the C-shaped yoke at least covering part sensing section, forms the arrangement states that flow guide bar mutually hooks drawing with C-shaped yoke.
The C-shaped yoke is made of permalloy, microcrystallizing alloy or silicon steel sheet.
The C-shaped yoke is made into integration using permalloy, or is formed by stacking using microcrystallizing alloy or permalloy, or
Person is formed by stacking using silicon steel sheet.
The utility model has the following advantages and effect compared with prior art：
1st, the utility model replaces unshakable in one's determination and winding using air core solenoid, reduces the consumption of precious metal material (copper),
Weight is alleviated, volume is reduced.2nd, the primary side for being easily achieved voltage and current loop in polyphase ac electrical measurement is electric
Separation, simplifies the Power Management Design of sample circuit.3rd, air core solenoid is fixed on the pcb board with embedded mode so that mutually
Sensor can be built in inside electric energy meter in the case where only taking up very little inner space, so as to greatly reduce the entirety of electric energy meter
Volume.4th, because without iron core, the utility model significantly improves without hysteresis effect and magnetic saturation phenomenon, bandwidth.5th, sense
It is not electrically connected between head and tested electric current, it is minimum on tested loop influence.6th, dynamic range is wider, can solve the problem that electrification
The electric energy metrical problem of the impact loads such as railway, large-scale electromagnetic oven.7th, cost is low.
Brief description of the drawings
Fig. 1 is the structure chart of current transformer in the utility model background technology.
Fig. 2 is the ammeter measurement loop schematic diagram that current transformer is used in the utility model background technology.
Fig. 3 is the utility model sensing head schematic diagram.
Fig. 4 is the embedded structural representation being fixed on pcb board of Fig. 3 sensing heads.
Fig. 5 is the front view of the utility model transformer.
Fig. 6-1 is the structure chart of monoblock type permalloy C-shaped yoke.
Fig. 6-2 is the structure chart of superposed type permalloy or microcrystallizing alloy C-shaped yoke.
Fig. 6-3 is the structure chart of superposed type silicon steel sheet C-shaped yoke.
Fig. 7 is the ammeter measurement loop schematic diagram using the utility model transformer.
Fig. 8 is the structural representation that the utility model is applied to three current loop measurements.
Fig. 9 is Fig. 8 explosive view.
Detailed introduction is done to the utility model below in conjunction with accompanying drawing.
As shown in figure 3, the present embodiment current transformer sensing head is a hollow spiral shell formed using wire uniform winding
Spool 1, solenoid output end connection current sampling circuit.
Preferably, the solenoid 1 is fixed on embedded mode on the pcb board 5 where the current sampling circuit；Such as
Shown in Fig. 4, specifically, opening up a groove on pcb board 5, solenoid 1 is positioned in the groove, two output end is welded in
On pcb board 5, and it is connected with the current sampling circuit on pcb board.
The internal diameter of the solenoid 1 is 0.5-1.5mm, corresponds to direct access (such as respectively：Ib=5A~10A, maximum electricity
Stream input 60A~200A) or input (such as through transformer：Rated current In=1A, maximum measurement electric current 2A~6A) etc. it is different should
Use demand；The winding number of turn is 1-10 circles, depending on the thickness (solenoidal height is less than or equal to the thickness of pcb board) of pcb board 5 and survey
Depending on the signal input range for measuring end.
As shown in Figure 5, Figure 7, current transformer described in the present embodiment includes foregoing sensing head, flow guide bar 2 and C-shaped yoke 3,
Flow guide bar 2, C-shaped yoke 3 is passed through by the bottom of C-shaped yoke C-channel, its two ends connect respectively live wire end of incoming cables and
Live wire leading-out terminal, after energization between two planes up and down of the openend of C-shaped yoke 3, is produced linear with current strength
Alternating magnetic field；
C-shaped yoke 3, the sensing head is inserted by the openend of C-shaped yoke 3, makes C-shaped yoke 3 that the biography is completely covered
Feel head, electromotive force is induced (specifically, generation becomes after flow guide bar is powered in the sensing head output end using the alternating magnetic field
The magnetic field of change, so as to induce a voltage signal proportional to electric current no-load voltage ratio in sensing head
Its induction coefficient M and coil factor kcoilWith magnet ring magnetic capacity kMagProduct it is related, be expressed as M=kcoil*kMag).This example
In, line (the most short company between two planes up and down of C-shaped yoke openend between 3 two ends (openend) of C-shaped yoke
Line) with the diameter parallel of air core solenoid, on the one hand constraint sensing head leakage field on the other hand prevent external magnetic field pair to external diffusion
The interference of measuring loop, improves measurement accuracy；In order to which external magnetic field interference is reduced into bottom line, C-shaped yoke 3 is covered in sensing
Resulting structure size on head must reach more than 10mmx10mm.
In order to ensure realizing the separation between voltage and circuit measuring loop, opening of the present embodiment in the C-shaped yoke 3
It is inserted with end and inserts the openend of C-shaped insulating trip 4 with its opening direction identical C-shaped insulating trip 4, the sensing head, make C-shaped magnetic
The sensing head is completely covered in yoke 3 and C-shaped insulating trip 4；The flow guide bar 2 encloses cavity from C-shaped yoke 3 and C-shaped insulating trip 4
Passed through in (being located at the bottom of C-channel).
In order to solve the Insulation Problems between flow guide bar 2 and air core solenoid 1, air core solenoid 1 should use enamel-covered wire around
System, and the wire needs lid insulation green oil on pcb board 5.
It is connected to form the end of incoming cables linkage section 2-1 of U-shaped, sensing section 2-2 preferably, the flow guide bar 2 includes order, goes out
Line end linkage section 2-3；Wherein end of incoming cables linkage section 2-1 connection live wires end of incoming cables, the 2-3 connection live wire outlets of leading-out terminal linkage section
End, sensing section 2-2 passes through the C-shaped yoke 3 so that the C-shaped yoke 3 at least covering part sensing section 2-2, forms flow guide bar
2 mutually hook the arrangement states drawn with C-shaped yoke 3.
The material of the c-type yoke 3 can select permalloy according to the difference of measuring accuracy, microcrystallizing alloy, or
Silicon steel sheet etc..The C-shaped yoke of three kinds of structure type is provided in the present embodiment, one kind is made up of monoblock type permalloy, such as Fig. 6-1
Shown, it is adaptable to high current direct measurement of the electric current between 5-200A, advantage is that measurement electric current is big, is difficult saturation, but linearly
Degree deficiency is, it is necessary to carry out segmented compensation；One kind is that permalloy or microcrystallizing alloy congruent manner (10 layers) are made, such as Fig. 6-2 institutes
Show, it is adaptable to low current (0.3-10A) measurement of more than 0.5S high accuracies requirement, the survey of the advantage of permalloy material laminate
Measure scope wide, have the disadvantage that the linearity needs compensation, and the advantage of microcrystallizing alloy lamination is that the measurement linearity is high, but range ability
It is slightly narrow, it is adapted to 0.2S grades of high-acruracy survey application scenarios；One kind is box-like (10 layers) for silicon steel sheet stack, as shown in Fig. 6-3, it is adaptable to
Low current (1-10A) measurement of 1.0 grades of medium error requirements, cost is relatively low.
As shown in Figure 8, Figure 9, it is necessary to set three to be arranged side by side when the present embodiment is applied to the measurement of three current loops
C-shaped yoke 3 and a C-shaped insulating trip 4, each C-shaped yoke 3 are correspondingly arranged a flow guide bar 2, and C-shaped insulating trip 4 inserts three simultaneously
The openend of individual C-shaped yoke 3.