JPH01187468A - Integral voltmeter - Google Patents

Abstract

PURPOSE:To eliminate the wastefulness and to improve a measuring speed higher by starting the settlement change of a pretreating device for a following integral measurement at the time when an input integration in the integral measurement is finished. CONSTITUTION:In the pretreating device to receive an A.C. input signal and the voltmeter to make an integral measurement of the output received from the pretreating device, switches S1-S8 are controlled by a microprocessor and a timing generator. The A.C. input signal is applied to terminals 1, 2 and an another A.C. input signal selected by the switches S1 and S2 is inputted to a phase generator PD. Then, the output having a standard phase component of the A.C. input signal as a D.C. component is obtained from the PD in such a manner as applying a reference input signal having the standard phase to a terminal 3, and whereby the settlement change of the pretreating device for the following integral measurement is made so as to start at the time when the input integration of the integral measurement is finished. That is, the changing-over of the input pretreating circuit is performed at the same time as separating the input of the integrator from a route of the input signal, so the wastefulness is eliminated and the measurement can be made at the higher speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an integral type voltmeter, and more particularly to an integral type voltmeter that eliminates dead time related to measurement and is faster.

[Prior art and its problems]

One of the instruments well suited for such uses is a measuring instrument called an integrating vector voltmeter. With this voltmeter,
After selecting the AC input signal to be measured, amplifying it, filtering it, etc.,
The output of phase detection using the reference signal of the reference phase is preferably integrated by an integral multiple of the cycle of the AC input, and the reference phase component of the AC input signal is determined from the integrated value. As the reference phase, a plurality of phases including two phases that differ by at least 90° are used. They are, for example, 0°, 90°, 180°, 270°
, and the reference phase component for them is the 0° component, 90
They are called the ° component, 180° component, and 270° component.

When measuring a large number of inputs with such a vector voltmeter, the input is switched to the input after the integral value measurement period following the integration period has elapsed. The same applies when it is necessary to switch the reference signal to a different phase. Therefore, the switching was delayed by the period of integral value measurement, making it impossible to perform measurements at high speed. Particularly in the case of double slopes or multiple slopes, the integral value is counted by discharging the integrator, resulting in a large switching delay.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an integrating voltmeter that switches the processing circuit in response to the end of an integration period to eliminate dead time and speed up measurement.

[Summary of the invention]

In one embodiment of the invention, switching the input pre-processing circuitry comprises:
Since the input of the integrator is disconnected from the input signal path and the AC input to be measured is switched at the same time, the rise waiting time of the preprocessing circuit until the integrator input is shortened by the integral value counting and calculation time.

[Embodiments of the invention]

FIG. 1 is a circuit diagram of an integrating type voltmeter according to an embodiment of the present invention. In this integral type voltmeter, switches S and -S are controlled by a microprocessor and a timing generator (not shown). An AC input signal is applied to the terminal 1.2, and one AC input signal selected by the switches s1 and S2 is input to the phase detector PD. A reference input signal having a reference phase is applied to the terminal 3 to obtain an output from the PD in which the reference phase component of the AC input signal is a DC component.

Figure 2 shows waveforms as a function of time t. The operation will be explained according to FIG. In Figure 2, waveform 1 is an example of the voltage waveform at the output terminal 4 of the integrating amplifier, and waveform -2 is an example of the voltage waveform at the output terminal 4 of the integrating amplifier, and waveform -2 shows the integral of the input when it is at a low level (between time t and tl). Indicates what will be done. That is, only one of the switches S, S2, 33, and S are closed, and the other switches are open.

Waveform-3 shows that when it is at a low level (from time t0 to R2) - times of integral measurements are performed and completed.

34, S5, and S8 are closed in the period tq to to, and S3
, S, are opened to initialize the integrator. Resistor R3
, R2 are grounded by switches S4, S, and the integrating capacitor C is shorted by switch S8. Here, it is assumed that SI is closed and S2 is opened. The voltage at terminal 4 becomes O.

In the period t0 to 1+, 51% Sol, S, is closed, and S
2.S?S...S? , S8 is opened. The voltage at terminal 4 is the current eD applied to the inverting input terminal of integrating amplifier A.
/R+ (where e is the output voltage of the phase detector PD, Ro
is the value obtained by integrating the resistance value of the resistor R1 connecting the switches S3 and S4 and the inverting input terminal of the integrating amplifier. Its value is e4. C is the capacitance value of the integrating capacitor C connected to the inverting input terminal of the integrating amplifier.

If t-to=Tz is chosen to be an integer multiple of the period of the AC component of eL, the value e41 at tl of R4 becomes e, the DC component of e.

Then becomes.

At t'=t, S3 and S are opened and S4 is closed.

Further, S6 or S7 is closed depending on the positive or negative output of the inverting amplifier ^2, and the DC voltage EI or E2 is applied to the resistor R2. Assuming that S6 is selected now, capacitor C is discharged by the current passing through resistor R2 (resistance value R2), and R4 descends with a downward slope to the right as shown in Figure 2, and finally reaches zero at time t2. becomes. Therefore, since tz L is counted and the known R,,E,,R
2. Eno is found from T2. Calculation of epo is t2
This is done between t3 and t3.

Next, open 37 and close S2 to measure the AC input at terminal 2, or leave S2 in the same state and connect terminal 3.
Measurement is performed by changing the reference phase of the reference input signal to.

Conventionally, the switching of switches S, S, and the variation of the reference phase of the reference input signal were performed after t and after R2.

In one embodiment of the present invention, these are performed at tl, so 1. -1. Therefore, switching of the switches S1 and S2 and changes in the reference phase input occur quickly, and the next measurement can be started quickly.

〔Effect of the invention〕

Therefore, implementation of the present invention advantageously enables high-speed measurements because dead time between successive measurements is reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an integral voltage type circuit according to an embodiment of the present invention, and FIG. 2 is a diagram showing waveforms and timing of the embodiment of FIG. 1. -1: Waveform of the output terminal 4 of the integrating amplifier ^1 -2 = Waveform indicating the integration period;: Waveform indicating the measurement period.

Claims (1)

[Claims] 1. Consisting of a preprocessing device that receives an AC input signal, and an integral voltmeter that receives the output of the preprocessing device and integrally measures the output, An integral type voltmeter characterized in that the setting change of the pre-processing device is started at the time when the input integration of the integral measurement is completed. 2. The integral type voltmeter according to claim 1, wherein the preprocessing device includes an input changeover switch, and the setting change includes switching the switch. 3. The integrating type voltmeter according to claim 1 or 2, wherein the preprocessing device includes a phase detector, and the setting change includes switching a reference input signal of the phase detector.