JPS633272A - Capacitor measuring instrument - Google Patents

Abstract

PURPOSE:To speed up the inspection by composing a direct reading for dielectric loss ratio and manufacturing deviation of electrostatic capacity of a capacitor. CONSTITUTION:The voltage between junctions (a) and (b), (h) and (g) are inputted respectively to a synchronous rectifier circuit 10 via amplifier circuits 6 and 7 to be rectified synchronously and inputted to a numerator of a division circuit 15. Further the voltage between junctions (b) and (g) is rectified 13 via an amplifier circuit 8 and inputted to a denominator of the circuit 15. The output of the circuit 15 is thereby indicated in a meter 17 as the dielectric loss ration. The output of the circuit 6 is then inputted to a synchronous rectifier circuit 11, and the output of the circuit 7 is phase shifted 12 by pi/2 radian and inputted to the circuit 11 to be rectified synchronously and inputted to a numerator of a division circuit 16. Further the voltage between junctions (a) and (g) is rectified 14 via an amplifier circuit 9 and inputted to a denominator of the circuit 16. The output of the circuit 16 is thereby indicated in a meter 18 as the deviation ratio to a capacitor of rated electrostatic capacity, i.e., manufacturing deviation. The inspection of the capacitor is accordingly speeded up.

Description

Detailed Description of the Invention (A) Industrial Application Field The present invention relates to a measuring instrument for measuring capacitance and dielectric loss of capacitors and cables, particularly on mass production lines. ) PRIOR TECHNOLOGY Conventionally, the capacitance and dielectric loss of capacitors and cables have been measured using a circuit shown in FIG.

The conventional circuit shown in FIG. 2 will be described below.

Connect the standard converter/su2 from one end of the electric picture l, and
A standard resistor 3 is connected in series with this, and it is connected to the other end of the power supply.Furthermore, another circuit connects one end of the power supply to the test capacitor lI (or the test cable, r
ib. The following explanation will be made using the test capacitor as a representative. ) is connected to L7, and a known resistor 5 is connected in series to the other end of the power supply.

To facilitate the following explanation, connection points are indicated by symbols as follows.

(1) The connection point between the standard capacitor, the capacitor under test, and one end of the power supply (g) (2) The connection point between the standard resistor, the known resistor, and the other end of the power supply (3) The standard capacitor and the standard resistance (4) Let the connection point of the resistor under test be d, and the connection point of the known resistor be b.

Further, one end of an amplifier circuit 17 is connected to this circuit from connection point 1 via a switch 16 for measurement. The contacts of the switch connected to the amplifier circuit are common, one contact is connected to -, and the other contact is connected to g.
It is connected to the. The other end of the amplifier circuit is connected to b.Furthermore, a meter 18 for measurement is connected to the output of the amplifier circuit.

Conventionally, capacitance and dielectric loss of capacitors and the like have been measured using such a circuit groove structure.Next, the principle of conventional measurement will be explained from an electrical theory. Before that, regarding the algebra of the circuit, V: Effective voltage of power supply [V Koge: Angular velocity of AC power supply [rad/33] Ge = 2 holes "Mini Pi": Frequency of AC power supply [Hz] C3: Standard Capacitance of the capacitor [F] R8: Resistance value of the standard resistor [-Q,] C: Capacitance ffi of the test capacitor [F1a: Conductance associated with power loss of the test capacitor [UcoR: Known] Resistance value of the resistor (standing) Now, in the 2N circuit, if we switch the switch to the connection point d side and find the formula for the voltage between the connection points a and lJ, we get the following ◇ In this equation (1), J: complex number j=, f: finished vQ: voltage between connection points a and b [■ 0 which is 0. In terms of circuit design, the algebra for this equation (1) is selected as follows.

R8 kuku 1 / lie c, --1------
−(2) R<(l/, ), c −−−−−−1−−−
- (3) L, 1 δ: is the dielectric loss ratio of the capacitor, and - is generally a small value of 0001 og (direct or 0), then formula (1) ignores terms that do not matter, and calculates V□ =V[O-R+ j ω(C-R-C3・R
5) becomes ◎From formula (5), change the value in parentheses to O, so C8
If v□ when the meter reading is minimized by turning the dial is V □ m, then v□m=V −G−R−
1------1-(6) ◎Also, C-R,= as-Rs-1--------(7
). From this formula (7), the capacitance of the test capacitor can be calculated from C=-・O5−−−−−−−−−−(8) ◇ Next, the measurement of the dielectric loss ratio of the capacitor is Switch the switch to the connection point g side and read it with the meter. Its value is: vr = v-w-c-a −−−−−−−−−−(9)
becomes. Vr is the voltage across the known resistor. Now, if we first find the ratio between equation (6), which is the minimum value of the meter reading, and the value of equation (9) above, we get V r V-u)-C-R1ad-(:, and (
The equation (lO) exactly indicates the dielectric loss ratio◎In other words,
It is the ratio of the readings of Lu om and V, which can be calculated.

(C) Problems that the invention aims to solve 7 With conventional measuring instruments, delicate adjustments were required by manually switching switches and carefully turning the dial of a standard capacitor on the meter. Although simple, calculations were required to determine the capacitance and dielectric loss ratio of the capacitor under test, making it difficult to conduct a complete inspection of products that flow in large quantities.

(D) Means for Solving the Problem In order to solve the above-mentioned problem, the present invention performs the following steps. 7) Calculate O8 from the formula and set it in advance.

(2) As mentioned above, 7 for the preset value,
In fact, the capacitance varies widely within ±5% with respect to its loft, so using the conventional measurement method, neither the capacitance nor the dielectric loss ratio can be determined◇ ( 3) Therefore, the present invention synchronously rectifies the voltage between the connection points a and b, VO, in accordance with the phase of the power supply voltage, obtains a value corresponding to equation (9), and calculates the voltage Iζ across the known resistor. Measure the dielectric loss ratio by dividing by the corresponding value.

(4) In addition, the present invention provides the above-mentioned v The deviation from the rated capacitance can be measured by dividing by the value of

The first part is about the circuit configuration of the measuring instrument of the present invention. For this configuration, the principle will be explained from an electrical theory. Regarding the above formula (5), 41-0・R---------------------- −(11)1+ = w
(C-R-C5-Rs) ++ -(12) "70=V(a÷, i b ) ------(1
3) can be shown as ◇ Expressing this equation (13) as an instantaneous value of an AC circuit that changes to 5 every moment, '1/"O2J"-V (, 5inuJ4+b-Co
s tJ-L )---(1・1). The instantaneous value of the power supply voltage is ν= JY t
V pot S i nω, L −−−−−−−(+5
) and 0.L in this equation is time [S].

Transforming equation (1.1), VO= , f"': -v lJJ7 lower + II"
・S in (cd・t + 6) 0t cos6 = +1 / , r −−−−−(17) S
in e = b 7 n ----(13) 0 ω-t of equation (16) is o-2 complete [: 5ρ = ω, also − -----------(19)
Then, VO=, J lower °, ■-1r; 7: Nib'-Sin (9
) +5 ) can be shown.

This voltage is rectified in synchronization with the power supply voltage.

First, synchronize with the voltage of the electric current (7teji=0~仝[rLL d
], the average voltage voltage after synchronous rectification is 10)・(l de π. Also, when synchronous rectification is performed from te=redo to 2fi [rad], it becomes a negative value as in equation (21). Since it is rectified, it becomes an absolute value, so the equation is exactly the same as equation (21).

Next, the power supply voltage is "/ 2 [r Ll d:l advance t
The average voltage vO2 synchronously rectified from 〇/2 to 3　/2 in synchronization with the voltage is 10) df.
When synchronously rectified up to
), and then substituting equation (18) into equation (11) and (I
2) By substituting the formula and rearranging it, we get 1 ----(24) 0 On the other hand, since the voltage across the known resistor is the current flowing through the test capacitor, the voltage V is higher than the voltage V in the hole I2. It's progressing. Therefore, the one-time value of this voltage is:
) = Ji, vua-c-R-Co59' +--
-(25), the average value simply rectified is as follows.

On the negative side, the voltage across the standard resistor is also the current flowing through the standard capacitor, so it leads/follows the power supply voltage V by ~2, and the instantaneous value of this voltage is VR8=Ji v-w, cs ・R8Sin (y
+ -) = 5 V-C4), C8-R8-C08CP
−(27). The rectified average value is as follows.

Now, the dielectric loss ratio of the capacitor is expressed as (23) by (26)
) formula, OIG □ = −−−−−−−−−(29nvRL4)・C, which is the dielectric loss ratio as in formula (10) ◇ Also, the capacitance of the capacitor is rated After adjusting the standard capacitor with a capacitor of value CC, keep it fixed.
In this case, when connecting a capacitor with the rated value and a different capacitor from the same lot, C in equation (24) is (Fuku Xl:
IC,)C=CC+MuC--1---130)
Therefore, equation (24) does not become 0, and (30
) into equation (24), ・Rs ------
--------(31) $ for winter, CC-R=C5-R8
Therefore, v02 is as follows. Dividing this equation (32) by equation (28), q 02 ΔC-R 'l/'RSI Cs, Rs -------"""
Becomes the basis. Furthermore, since C8 was adjusted 7 at the time of momentum, C3-R8=CG-R---(34), and substituting equation (33) into equation (3-1), 'L/'Rs Cc-Rcc , the manufacturing deviation ratio of the capacitor is found to be 0 or more,
The measurement method described at the beginning of this section has been verified.

(F2) Measuring instrument circuit to solve the problem (D) above
Based on the theoretical proof for solving the problem, the circuit of the measuring instrument of the present invention will be explained except for the circuit configuration shown in FIG. 1 and the same part as in FIG. 2.

To measure the dielectric loss ratio, the voltage between the connection points a and b is passed through the A amplifier circuit 6, and the voltage between the connection points 11.0 and 11.0 is passed through the B amplifier circuit 7. Out car! - input to the synchronous rectifier circuit 10 0 Note that the signal input from the BbB width circuit is shaped into a square wave by the A synchronous rectifier circuit,
The signal input from the A amplifier circuit is synchronously rectified at the timing of this pigeon wave, and an output proportional to the above equation (23) is produced. This is used as the numerator side input of the A divider circuit 15. Furthermore, the connection point and the voltage between g is passed through the C amplifier circuit 8,
It is rectified by the A rectifier circuit 13 and outputs an output proportional to the above equation (26). C is the denominator side input of the A division circuit. Therefore, the output of the A division circuit is proportional to the above equation (29), and the A meter 17 indicates the dielectric loss ratio.

The measurement of the manufacturing capacitor deviation ratio of the rated capacitance is carried out using the above-mentioned A.
The output of the amplifier circuit is input to the B synchronous rectifier circuit 11, and the output of the B amplifier circuit is input to the phase shift circuit 12.
Advance (may be delayed) 0 input to B synchronous rectifier circuit
Note that the signal input from the phase shift circuit is shaped into a long blind wave by the B synchronous rectifier circuit, and the signal input from the A amplifier circuit is shaped into a long blind wave at the timing of the phase shifted square wave. Synchronous rectification is performed to produce an output proportional to the above equation (32). This is used as the numerator side input of the B division circuit 16.

Furthermore, the voltage between the connection point "%g" passes through the D amplifier circuit 9,
It is rectified by the B rectifier circuit and outputs an output proportional to the above equation (28). This is the denominator side input of the B divider circuit. Therefore, the output of the B divider circuit is an output proportional to the above equation (35). Showing the manufacturing deviation ratio ◇ (F) Effects of the invention (1) The dielectric loss ratio of the capacitor and the manufacturing deviation of the capacitance can be directly read, speeding up inspection.

(2) It is not affected by fluctuations in the power supply voltage as in equations (29) and (35) of tnJ. In other words, the power supply voltage V is reduced.

(3) This means that capacitors and the like have voltage characteristics, and the dielectric loss ratio, including corona loss, can be measured depending on the voltage.

(4) Since it is not easily affected by voltage, it can also be applied to the measurement of high-voltage capacitors, etc. (5) It is possible to calculate Rs and R in equations (2) and (3) above.
By designing with a very small value, the loss of the measuring instrument is reduced, it is economical, and the temperature stability of the measuring instrument itself is improved.

0 (G) Other embodiments with the above effects Synchronous rectification was performed based on the power supply voltage in equation (15) (7), but under the conditions of equation (2), the voltage across Rs is ( 27
) is as follows. This deceased has already been transferred to ``I/2''
voltage (7) applied to the input of the B synchronous rectifier circuit in FIG.

Also, in order to make this R8 the phase of the power supply voltage, it is phase shifted by 2 holes and applied to the input of the A synchronous rectifier circuit.

This method is also an embodiment of the present invention.

In addition, the circuit of the embodiment shown in FIG.
As described in mathematical detail above, the outputs of the A, B, and D amplifier circuits are processed by processing (analog IC) at a specific timing (when the voltage crosses zero). sampling and holding, and A/D conversion circuit (analog, peak timing).
It is also possible to process digitally by a microcomputer via a digital conversion circuit. Also,
The output from the synchronous rectifier and rectifier circuit in the circuit shown in FIG. This is an example that falls within the scope of mathematical expression.

Further, the standard capacitor (C!S) in FIG. 1 may be a fixed capacitor, and the standard resistor 2 (R8) may be a fixed resistor, resulting in an embodiment that falls within the scope of the above-mentioned mathematical expression.

[Brief explanation of the drawing]

FIG. 1 is a measurement circuit diagram of an embodiment of the present invention. 1 is an AC power supply, 2 is a standard capacitor 3 is a standard resistor, 4 is a test capacitor 5 is a known resistor, 6.7.8.9 are A, B, C, D amplifier circuit 10.11,
is A%B synchronous rectifier circuit 12 is phase shift circuit 13.14 is A, B rectifier circuit 15.16 is A, B division circuit 17.18 is AS B meter. Circuit t is a phase shift circuit. Do is a rectifier circuit ÷ is a divider circuit. H is a meter. 0 Figure 2 is a conventional measurement circuit diagram.

Claims (1)

[Claims] In Fig. 1, a standard capacitor (or standard resistor) is varied to the rated capacitance (or specific capacitance) of the capacitor, and the voltage between connection points a and b is adjusted to around the minimum. After
Connect a test capacitor from the same lot as the above capacitor. At that time, the dielectric loss ratio is measured by dividing the voltage that is synchronously rectified in the same phase as the power supply voltage between the connection points a and b by the rectified voltage between the connection points b and g. Furthermore, the voltage obtained by synchronously rectifying the voltage between the connection points a and b with the same phase as the voltage phase-shifted by π/2 [had] with respect to the power supply voltage is divided by the rectified voltage between the connection points a and g, and the capacitance is Measure the deviation ratio. Or, as mentioned above, π with respect to the power supply voltage
The voltage between the connection points a and g is set to the voltage whose phase is shifted by /2 [had], and the voltage whose phase is shifted by π/2 [had] from the voltage between a and g is the voltage that has the same phase as the power supply voltage. synchronous rectification. A capacitor measuring device that applies one of these