SU492201A1 - Device for measuring voltage phases and amplitudes - Google Patents

Description

FROM t And the useful stability of the amplitude at the output of such an eveng because any change in T due to the instrumentation (the 1st spread will simultaneously enter the numerator and denominator of the transfer function. Moreover, these errors are easily taken into account when calibrating the instrument. The device also includes the adder 3, which is fed to the input signal and from a low-frequency generator of periodic oscillations (NGPK) along two parallel chains. On the circuit, the signal passes inertia-free, and along circuit 5 through inertial link 6 of type y and invertiroclemde link 7 with Wux It is equal to 2. Such an inclusion allows the implementation of the following transfer function:) Tf; apt o which both the numerator and the denominator depend on only one time constant T defined by link 6. The output signal Uj from the adder 3 is then fed to one of the inputs of the oscilloscope 2 {horizontal or vertical). To the other input of the oscilloscope (respectively, vertical or horizontal), the signal Uj is output from the object under study 8. In the approximate electrical circuit of the proposed device (see Fig. 2), the role of adder 3 is played by operational amplifier 9, and the role of inertial link 6 and inverting The link 7 is executed by the operational amplifier 10. In feedback, the amplifier 10 is connected in parallel with the resistance to an electrical capacitor C, the magnitude of which may change during the investigation (for example, the capacitor bank).

The device works as follows.

Claims (1)

The signal of sinusoidal oscillations U with NGPK is applied to the object B and simultaneously to the phase-shifting circuit 1. In the presence of a phase shift other than zero, an ellipsoidal curve is observed on the oscilloscope screen. With the help of a capacitor C, the ellipse T is selected. turns into a straight line, which indicates the equality of the phases of the object under study and the phase-shifting circuit. Knowing the time constant T and the frequency of the signal U / (f. .. fn), it is very easy to determine the phase shift from the graph (see Fig. 3). Apparatus of the Invention A device for measuring amplitudes and phases of voltages comprising a phase-shifting circuit, a low-frequency generator of periodic oscillations, an oscilloscope, and a test object, characterized in that, in order to improve the accuracy of phase shift measurement and simplify the design,. phase shifting the circuit is made in the form of a summed device device, one input of which is connected directly to the output of the low-frequency periodic oscillator, and the other input through a series-connected inertial link of the type V / (p) "-4-j and inverting link with doubled gain, the output of the summing device is connected to one input of the oscilloscope, the other input of which is connected to the output of the object under study. Fig.Z