JP3632074B2 - Standard voltage divider calibration method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
Calibration of standard voltage dividers in the field of electrical measurement.
[0002]
[Prior art]
A standard voltage divider knows its voltage division ratio, keeps a point at the rated ground potential,
After applying the rated voltage, the voltage division ratio is used for measurement.
Most of the self-calibration methods used to determine the voltage division ratio estimate this effect because (1) ground potential and (2) rated voltage at the time of calibration differ from the actual values used. There was inconvenience that was necessary. On the other hand, the inventors have invented an excellent method that can self-calibrate the voltage division ratio while maintaining (1) ground potential and (2) rated voltage during actual use of the standard voltage divider, and has already published [Yasuhiko Sakamoto, Tadashi Endo, Toshiki Sakuraba, “A 10 V calibrating system using an automated voltage divider and a1 V Josephson. Instrum. Meas. , Vol. 42, no. 2, 583-587 (1993). Y. Sakamoto, Tadashi Endo, Shao Haiming, Sosuke Matsuwa, “Automated dc voltage divider to calibrate voltage up to 1 cV” 36 CP ].
[0003]
This new method provides a reference voltage source that is electrically isolated and grounded separately from the ground while maintaining the voltage divider's (1) ground potential and (2) rated voltage. And the voltage drop across the output terminals of the standard voltage divider.
[0004]
[Problems to be solved by the invention]
However, when the rated voltage of the standard voltage divider is increased, it becomes difficult to keep the insulation between the reference voltage source and the ground sufficiently high, causing a problem that current leaks from the reference voltage source to the ground. Since this leakage current circulates the circuit including the standard voltage divider, there arises a disadvantage that the current flowing through the standard voltage divider is different from the rated current. Therefore, the magnitude of this leakage current is evaluated and its influence is affected. There was a need for a correction method.
[0005]
[Means for Solving the Problems]
Between the terminals of the standard voltage divider and the floating reference voltage source, one pair is short-circuited (C) and the other pair is connected to a voltmeter (D) as shown in FIG. Here, the gist of the present invention is to use a voltmeter (d) having a high input impedance and to measure the differential voltage by the two connections shown in FIGS. 1 (a) and 1 (b). When the voltmeter (d) has a high input impedance, the leakage current (3) that flows due to incomplete insulation between the floating reference voltage source and the ground flows from the standard voltage divider through the short circuit (c). However, in the case of (a) and (b), the voltmeter (D) gives different instructions because the current flows out from which terminal of the standard voltage divider. This may be corrected by circuit analysis.
[0006]
【Example】
In the standard voltage divider having a rated maximum voltage of 1000 V as shown on the left in FIG. 1, the nominal potential of the output terminals to ground is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 9, 10, 20, 30 , 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000V, apply a rated voltage of 1000V, and on the right side of FIG. The ratio of the voltage drop between the terminals of the standard voltage divider is measured using a voltage drop of 1 V, 10 V, or 100 V of a floating reference voltage source as a reference voltage. At that time, the differential voltage measurement is performed by the two connections of FIG. 1 (a) and (b).
[0007]
When the reading of the voltmeter at the time of connection (a) is Va, and the reading of the voltmeter at the time of connection (b) is Vb, for example, the nominal nx 100 V terminal of the standard voltage divider and the nominal (n-1) x The difference between the voltage drop between the 100 V terminal and the output voltage of 100 V of the floating reference voltage source is {(n−1) Va + (10−n) Vb} / 9. Knowing from the circuit analysis that it is a value when (3) can be made zero, the value is used.
[0008]
In this way, even though the leakage current (3) is not actually zero, the measurement is performed with the two connections of FIG. 1 (a) and (b), and this is repeated for each terminal pair. Thus, the voltage division ratio of the standard voltage divider when there is no influence of the leakage current is obtained. The standard voltage divider that calibrates the voltage dividing ratio in this way can be used as a national standard.
[0009]
【The invention's effect】
[Brief description of the drawings]
Fig. 1 Circuit diagram for calibrating the voltage division ratio of a standard voltage divider [Explanation of symbols]
(A) Standard voltage divider (b) Floating reference voltage source (c) Short-circuit connection (d) Voltmeter (e) Resistance indicating incomplete insulation (f) Earth

Claims (1)

When measuring the voltage between the output terminals of the standard voltage divider compared to the floating reference voltage source, the voltage divider and the floating reference voltage source must be A method for calibrating a standard voltage divider, characterized by exchanging and measuring circuit connections of two potentials to be connected.

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