JP2687615B2 - Switch arc voltage measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an arc voltage measuring device for a switch.

B. Outline of the Invention The present invention is an arc voltage measuring device for a switch, which measures the arc voltage at the time of opening by introducing the voltage across the test switch to a measuring device, and has an impedance equivalent to that of the test switch. By using an impedance component and canceling the voltage drop due to the impedance component of the switch itself by the voltage across it, the true arc voltage can be measured.

C. Conventional technology The arc voltage generated when the contact is opened in the switch test is an important parameter for performance analysis. In addition, 1 of the test result items specified in various standards
It can be said that directly measuring the arc voltage is a very effective means for knowing the "arc time" which is one of the two from the viewpoint of accuracy.

For this reason, the arc voltage is conventionally measured by the measuring circuit shown in FIG. In the figure, E is an AC power supply,
1 is a switch under test, 2 is a voltage divider for voltage measurement, 3 is a clip device, and 4 is a measuring instrument for waveform observation.

FIGS. 3 (a) and 3 (b) are current waveform diagrams of the circuit of FIG. 2, respectively, showing the voltage between contacts of the test switch 1, and a voltage is generated between the contacts of the test switch at the same time as energization. ing. This is based on the voltage drop caused by the current flowing through the impedance of the test switch itself.

D. Problem to be Solved by the Invention By the way, the voltage based on the arc is zero before the opening point and a waveform appears after the opening point, as shown in FIG. 3 (c). However, the voltage waveform obtained by an actual measurement circuit is
As described above, the impedance-based voltage is superimposed on the arc voltage, and it is the same as the state in which noise is included when measuring an accurate arc voltage, which prevents accurate measurement of the arc voltage. It was

An object of the present invention is to measure arc voltage with high accuracy.

E. Means for Solving the Problem The present invention has an impedance component equivalent to that of a test switch, and an impedance component connected in series with the test switch and a voltage level of a voltage across the impedance component. A gain adjusting amplifier, and an adder for adding the output voltage of the amplifier and the output voltage of the voltage divider with opposite polarities.

F. Action If the gain of the gain adjustment amplifier is adjusted to make the levels of both input voltages of the adder equal, the voltage drop due to the impedance of the switch itself is canceled and the true arc voltage can be measured.

G. Embodiment FIG. 1 is a view showing an embodiment of the present invention, in which the same symbols as in FIG. 2 indicate the same parts. In this embodiment, an impedance component 5 having an impedance equivalent to that of the DUT 1 is connected in series to the DUT 1, and both ends of the impedance component 5 are connected to both inputs of a gain adjusting amplifier 6. Connect to the end. 7 is an adder,
The output voltage from the clipping device 3 and the output voltage from the amplifier 6 are added so that their polarities are opposite to each other.

In the above, the above equivalent impedance is
The impedance is such that the phase relationship between the voltage and the current is the same. Specifically, the reactor, the capacitor, and the resistor are used alone or in combination.

The voltage across the impedance component 5 may be directly applied to the amplifier 6, or may be divided and applied.

According to the above configuration, first, the gain of the amplifier 6 is adjusted so that the output voltage levels of both input terminals of the adder 7 are aligned before opening. On the other hand, the voltage drop due to the impedance of the test switch 1 itself is divided by the voltage divider 2 and input to the adder 7, but the voltage drop here is canceled by the voltage from the amplifier 6. Therefore, when the test switch 1 is opened, only the voltage corresponding to the arc voltage at that time is given to the measuring device 4 from the adding section 7, and the arc voltage waveform in the measuring device 4 is as shown in FIG. 3 (c). It will be ideal.

H. Effect of the Invention According to the present invention, since the voltage drop due to the impedance of the test switch itself is canceled by the voltage across the impedance component, it is possible to measure the true arc voltage and improve the measurement accuracy. To do. Further, although the amount of cancellation is adjusted by changing the gain of the amplifier, once the gain is set, there is no need to adjust the gain thereafter, and the operation is simple.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a conventional example, and FIG. 3 is a waveform diagram of current and arc voltage. 1 ... Test switch, 2 ... Voltage divider, clip device, 4 ...
… Measuring instrument, 5 …… impedance component, 6 …… gain adjustment amplifier, 7 …… adding section, E …… AC power supply.

Claims (1)

(57) [Claims] 1. An arc voltage measuring device for a switch, which measures the arc voltage at the time of opening by introducing the voltage across the test switch to a measuring device through a voltage divider, and an impedance equivalent to that of the test switch. An impedance component connected in series with the switch under test, a gain adjustment amplifier for adjusting the voltage level of the voltage across the impedance component, and the output voltage of this amplifier and the output voltage from the voltage divider. An arc voltage measuring device for a switch, characterized in that an adder section for making the reverse polarity and adding is provided, and the levels of both input voltages of the adder section are made uniform by adjusting the gain of the amplifier.