CN201654135U - Transformer LC detector - Google Patents

Abstract

The utility model belongs to the field of electrotechnology, and relates to an instrument measuring transformer windings Lx and Cx, wherein 8038 is used for generating sine waves; signals are provided for an amplifier consisting of operational amplifiers N3 from the P1 point through a voltage follower; the non-inverting input ends of the N3 are connected with the ground wire of the instrument, the inverted input ends thereof are connected with the P2 point, the output end is connected with the P3 point, the Ro is connected with the P1 and the P2; two ends of the transformer winding are connected with the P2 and the P3; a capacitor Co is connected with the P2 and P3 points through a switch K; the frequencies when the voltage of the P3 point is the maximum value under the situations of switch connection and disconnection are measured, and Lx and Cx are calculated according to the formula.

Description

Transformer LC detector

Technical field

The utility model belongs to the electrotechnics field.

Background technology

In the testing of power transformer, measure the inductance value L of its winding coil _xWith electric capacity C _xBe one of important project, because complex structure can not directly be measured with commercially available secohmmeter and capacitance meter, though can use electric bridge to measure, owing to need the parameter of adjustment many, complicated operation uses inconvenience.

Summary of the invention

The utility model technical issues that need to address are the deficiencies that overcome bridge measurement complicated operation inconvenience, and a kind of new measurement instrument is provided, the speed and convenience inductance L that detects the Transformer Winding coil _xAnd capacitor C _x

Concrete technical scheme of the present utility model is, N1 is a function generator integrated circuit 8038, and N2～N5 is an integrated operational amplifier, R _P1And R _P2Be potentiometer, be connected into variable-resistance R _P1One termination positive supply+U, other end connecting resistance R ₁An end, R ₁The other end meet N simultaneously ₁4 and 5 pin, N ₁6 pin connect+U resistance R ₂Two ends connect respectively+U and N ₁9 pin, N ₁7 be connected N with 8 pin ₁11 pin meet negative supply-U, capacitor C ₁Two ends meet N respectively ₁10 pin and-U, resistor R ₃Two ends meet N respectively ₁12 pin and-U, N ₁The sine voltage frequency of 2 pin output by R _P1And C ₁Value decision, change R _P1And C ₁Value, can change frequency f; Resistor R ₄2 pin of a termination N1, another termination R _P2An end points, R _P2Another end points connect the ground wire of instrument, R _P2Centre tap meet N ₂In-phase input end, N ₂Inverting input and its output terminal meet P simultaneously ₁Point, P ₁Voltage=the U of point ₁Resistor R _oTwo ends meet P respectively ₁And P ₂Point, N ₃In-phase input end meet instrument ground wire, N ₃Inverting input meet P ₂Point, N ₃Output termination P ₃Point, P ₃Voltage=the U of point ₂, fixed condenser C _oMeet P by K switch ₂And P ₃Point, two end points of transformer coli winding to be measured connect P2 and P3 point respectively; N ₄In-phase input end pass through resistor R ₅Meet P ₃Point, diode V ₂Positive pole meet N ₄Inverting input, V ₂Negative pole meet N ₄Output terminal, diode V ₁Positive pole meet N ₄Output terminal, V ₁Negative pole meet P ₄Point, resistor R ₆A termination N ₄Inverting input, another termination P ₄Point, capacitor C ₂A termination P ₄Point, another termination is line instrumentally, resistor R ₇Two ends meet P respectively ₄And P ₅Point, capacitor C ₃A termination P ₅Point, another termination is line instrumentally; N ₅In-phase input end meet P ₅Point, the inverting input of N5 is connected with output terminal, N ₅Output voltage V _oBe proportional to U ₂Measure and carry out in two steps, the first step, cut-off switch K changes U by the value that changes Rp1 and C1 ₁Sinusoidal wave frequency makes V _oBe maximal value, at this moment get frequency f ₁, in second step, the K that closes a switch changes frequency again, makes V _oBe maximal value, obtain frequency f ₂, calculate L with formula (1) and (2) _xAnd C _xValue.Theoretical analysis as can be known, the equiva lent impedance Zx=Cx/ of Transformer Winding coil to be measured/(Lx+Rx), wherein symbol // expression is in parallel, (Lx+Rx) expression Lx and Rx series connection, and fixed condenser Co parameter is known, when K switch disconnects, U2=-(U1/Ro) Zx, when closing a switch K, U2=-(U1/Ro) Zx*, ZX*=(Cx+Co) // (Lx+Rx) wherein, symbol (Cx+Co) expression two capacitor parallel connections; Because Vo is proportional to U2, measure that K is disconnected to close frequency f 1 and f2 when Vo is maximal value under two kinds of situations with K, calculate the value of Cx and Lx by formula (1) and (2), wherein

(2fπf1) ²L _xC _x＝1 ----------------------(1)

$C_x=\frac{C_o}{{\left(\frac{f_1}{f_2}\right)}^2-1}---\left(2\right)$

Owing to adopted such scheme, can measure the inductance L of Transformer Winding very easily _xAnd capacitor C _xValue, and apparatus structure is simple, compares with traditional electric bridge, and is easy to operate, only needs to adjust the value of Rp1 and C1, measuring two Vo is that peaked frequency gets final product.

Description of drawings

Fig. 1 is an electrical schematic diagram of the present utility model.

Embodiment

Below in conjunction with accompanying drawing the utility model is further described.

N among the figure ₁～N ₅Be integrated circuit, N ₁Be function generator integrated circuit 8038, N ₂～N ₅It is integrated operational amplifier; By N ₁Form sine-wave generator, N with relevant Resistor-Capacitor Unit ₂Be connected into voltage follower circuit, N ₃Be connected into anti-phase proportional amplifier circuit, N ₄Form half-wave rectification and filtering circuit, N with related elements ₅Be connected into voltage follower circuit; R _P1And R _P2Be potentiometer, be connected into variable-resistance R _P1One termination positive supply+U, other end connecting resistance R ₁An end, R ₁The other end meet N simultaneously ₁4 and 5 pin, N ₁6 pin connect+U resistor R ₂Two ends connect respectively+U and N ₁9 pin, N ₁7 be connected N with 8 pin ₁11 pin meet negative supply-U, capacitor C ₁Two ends meet N respectively ₁10 pin and-U, resistor R ₃Two ends meet N respectively ₁12 pin and-U, N ₁2 pin sine wave output voltages, change R _P1And C ₁Value, can change sinusoidal wave frequency f; Resistor R ₄2 pin of a termination N1, another termination R _P2An end points, R _P2Another end points connect the ground wire of instrument, R _P2Centre tap meet N ₂In-phase input end, N ₂Inverting input and output terminal meet P simultaneously ₁Point, P ₁Sine voltage=the U of point ₁Resistor R _oTwo ends meet P respectively ₁And P ₂Point, N ₃In-phase input end meet instrument ground wire, N ₃Inverting input meet P ₂Point, N ₃Output termination P ₃Point, P ₃Voltage=the U of point ₂, the two ends of transformer coil to be measured meet P respectively ₂And P ₃Point, fixed condenser C _oMeet P by K switch ₂And P ₃The point; N ₄In-phase input end pass through resistor R ₅Meet P ₃Point, diode V ₂Positive pole meet N ₄Inverting input, V ₂Negative pole meet N ₄Output terminal, diode V ₁Positive pole meet N ₄Output terminal, V ₁Negative pole meet P ₄Point, resistor R ₆A termination N ₄Inverting input, another termination P ₄Point, capacitor C ₂A termination P ₄Point, another termination is line instrumentally, resistor R ₇Two ends meet P respectively ₄And P ₅Point, capacitor C ₃A termination P ₅Point, another termination is line instrumentally; N ₅In-phase input end meet P ₅Point, the inverting input of N5 is connected with output terminal, N ₅Output dc voltage V _oBe proportional to U ₂Measure and carry out in two steps, the first step, cut-off switch K changes U by the value that changes Rp1 and C1 ₁Sinusoidal wave frequency makes V _oBe maximal value, at this moment get frequency f ₁, in second step, the K that closes a switch changes frequency again, makes V _oBe maximal value, obtain frequency f ₂, calculate L with the formula that provides above _xAnd C _xValue.

Claims (1)

1. transformer LC detector is characterized in that described instrument, N ₁Be function generator integrated circuit 8038, N ₂～N ₅Be integrated operational amplifier, R _P1And R _P2Be potentiometer, be connected into variable-resistance R _P1One termination positive supply+U, other end connecting resistance R ₁An end, R ₁The other end meet N simultaneously ₁4 and 5 pin, N ₁6 pin meet+U R ₂Two ends connect respectively+U and N ₁9 pin, N ₁7 be connected N with 8 pin ₁11 pin meet negative supply-U, capacitor C ₁Two ends meet N respectively ₁10 pin and-U, resistor R ₃Two ends meet N respectively ₁12 pin and-U, N ₁The sine voltage frequency of 2 pin output by R _P1And C ₁Value decision, change R _P1And C ₁Value, can change frequency f; Resistor R ₄2 pin of a termination N1, another termination R _P2An end points, R _P2Another end points connect the ground wire of instrument, R _P2Centre tap meet N ₂In-phase input end, N ₂Inverting input and its output terminal meet P simultaneously ₁Point, P ₁Voltage=the U of point ₁Resistor R _oTwo ends meet P respectively ₁And P ₂Point, N ₃In-phase input end meet instrument ground wire, N ₃Inverting input meet P ₂Point, N ₃Output termination P ₃Point, P ₃Voltage=the U of point ₂, fixed condenser C _oMeet P by K switch ₂And P ₃Point, two end points of transformer coli winding to be measured meet P respectively ₂And P ₃The point; N ₄In-phase input end pass through resistor R ₅Meet P ₃Point, diode V ₂Positive pole meet N ₄Inverting input, V ₂Negative pole meet N ₄Output terminal, diode V ₁Positive pole meet N ₄Output terminal, V ₁Negative pole meet P ₄Point, resistor R ₆A termination N ₄Inverting input, another termination P ₄Point, capacitor C ₂A termination P ₄Point, another termination is line instrumentally, resistor R ₇Two ends meet P respectively ₄And P ₅Point, capacitor C ₃A termination P ₅Point, another termination is line instrumentally; N ₅In-phase input end meet P ₅Point, N ₅Inverting input be connected N with output terminal ₅Output voltage V _oBe proportional to U ₂

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