JPH0328392Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in high-voltage switchgear such as high-voltage circuit breakers, electromagnetic contactors, and switches.
In recent years, with the increase in the size of equipment in factories, the capacity of electrical equipment has increased, and the use of high-voltage equipment such as high-voltage motors, transformers, and capacitors has continued to increase. In order to properly maintain these high-voltage devices, it is extremely important to measure the insulation resistance to ground (hereinafter referred to as insulation resistance) of the high-voltage devices and the high-voltage cables connected to the high-voltage devices. However, the preparatory operations for measuring the insulation resistance are complicated and risky. That is, the insulation resistance is usually measured using a circuit breaker connected to the high voltage equipment by a high voltage cable;
This is done between the main circuit secondary terminal of a high voltage switchgear such as an electromagnetic contactor and the ground terminal with the high voltage switchgear open, but the surface of the main circuit secondary terminal is insulated with tape, etc. to prevent electric shock. The insulating part must be removed for each measurement. Further, most of the high voltage switchgear is housed in a cubicle to prevent electric shock. Therefore, if there are high-voltage live wires inside the cubicle, it is dangerous to measure insulation resistance at the main circuit secondary terminals of the high-voltage switchgear located deep inside the cubicle, as there is a risk of touching the high-voltage live wires during the measurement. . In particular, in the case of a draw-out type high voltage switchgear that does not use a disconnector on the primary side of the high voltage switchgear, the main circuit secondary terminal is generally located on the back of the cubicle, and the main circuit primary terminal is a high voltage live wire. It is extremely dangerous to measure insulation resistance at the secondary terminals of the main circuit.

Therefore, in electrical equipment using high-voltage power supplies,
The development of a device that can be easily operated before insulation resistance measurement and that can safely measure insulation resistance is a major challenge.

The inventors of the present invention have made earnest efforts to solve the above problems. As a result, a lead-out terminal for measuring insulation resistance is provided in the secondary circuit of the high-voltage switchgear via a rectifying element and a resistor, and this lead-out terminal is placed at an arbitrary position where it can be easily measured. Then, they discovered that insulation resistance can be easily and safely measured with a simple configuration, and that the resistor has almost no effect on the measurement of insulation resistance, leading to the proposal of the present invention.

That is, the present invention is a high-voltage switchgear in which a lead-out terminal for measuring insulation resistance is provided in the secondary circuit of the high-voltage switchgear through a rectifying element and a series resistor.

In the present invention, known high voltage switching devices such as circuit breakers, electromagnetic contactors, switches, etc. are generally used.

By configuring the high voltage switchgear as described above, insulation resistance can be measured between the lead-out terminal for insulation resistance measurement and the ground terminal. Therefore,
The lead-out terminal for measuring insulation resistance can be provided at any convenient position. Therefore, there is no risk of touching the high-voltage live wire when measuring insulation resistance, and even in the case of the draw-out type high-voltage switchgear, there is no risk of touching the main circuit primary terminal of the high-voltage switchgear.
Measurements are taken safely. Further, even when the high-voltage switchgear is turned on and energized, the arrangement of the rectifying means in the sending direction prevents electrocution even if someone touches the lead-out terminal for measuring insulation resistance. In addition, even if a small animal such as a mouse touches the terminal and causes a ground fault, the current that flows is only a small amount of leakage current from the rectifying element.
It has the advantage of not activating safety devices, such as earthing relays, which are normally provided in high voltage circuits. Therefore, the lead-out terminal for insulation resistance measurement can be kept exposed at all times, and insulation resistance can be measured safely and easily. The resistance value of a resistor inserted in series for protection varies depending on the type of main circuit power supply, voltage, etc., and cannot be uniformly limited, but generally when a person touches the lead-out terminal for insulation resistance measurement while the current is on, the resistance value is 30mA, Hereinafter, it may be determined that a current of preferably 20 mA or less flows. For example, if the current is 3KV, 3-phase, 3-wire system with neutral point grounded,
In order to reduce the current to 20 mA or less, the resistance value R of the resistor may be determined so that R≧(3000/√3)/20×10 ^-3 ≒87KΩ. In addition, in order to keep the lead-out terminal for insulation resistance measurement even safer, it is a preferable embodiment to make the terminal so small that it cannot be grabbed by a person.

Generally, when measuring insulation resistance, the presence of a resistor having such a large resistance value in the measurement circuit is expected to have a considerable influence on the actually measured insulation resistance value. However, even if the resistor is present in the measurement circuit, the insulation resistance can be sufficiently measured in practice. In other words, the insulation resistance value measured at the lead-out terminal for insulation resistance measurement is displayed as the sum of the true insulation resistance value and the resistance value of the resistor, but the resistance value is smaller than the actual insulation resistance value. Since it is small, it has almost no effect on insulation resistance measurements. In particular, when the main circuit power source is AC and a reactor is used as the resistor, the reactor has an extremely small resistance value with respect to the DC power source used for measuring insulation resistance, so it is preferable because it does not affect the measurement of insulation resistance at all.

The present invention will be specifically described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.

The drawing shows a circuit diagram in which a high voltage switchgear according to a typical embodiment of the present invention is incorporated into electrical equipment when a three-phase AC power source is used in the main circuit. A rectifying element 4 and a resistor 5 are connected to one of the main circuit secondary terminals 3-3 of the high voltage switchgear 1.
In this embodiment, a lead-out terminal 6 for measuring insulation resistance is connected through the terminal. In addition, in the drawing, 8 is a high-voltage device, and each core wire 7-1 of the high-voltage cable,
It is connected to each high voltage secondary terminal 3-1, 3-2, 3-3 of the high voltage switchgear 1 through 7-2, 7-3. Moreover, 2-1, 2-2, 2-3 are each main circuit primary terminal of the AC high voltage switchgear 1. In the drawing, by connecting the measurement terminal of a known insulation resistance meter, for example, which compensates for the resistance value of the resistor 5, to the lead-out terminal 6 and the ground terminal provided at arbitrary positions,
The insulation resistance of each core wire 7-1, 7-2, 7-3 of the high-voltage cable, the AC high-voltage device 8, and each internal secondary circuit 9-1, 9-2, 9-3 of the high-voltage switchgear is measured.

Furthermore, when measuring the insulation resistance of each core wire of a high-voltage cable connected to the primary side of the high-voltage switchgear in electrical equipment in which a high-voltage switchgear is separately provided in place of the high-voltage equipment 8 in the drawings, the high-voltage switchgear of the present invention can be used. The device connects the insulation resistance measuring terminal to each main circuit secondary terminal of the high voltage switchgear shown in the drawing, to each core wire of the high voltage cable, or to each main circuit primary terminal of the high voltage switchgear separately provided above, through a rectifier. It can be configured as follows. In the example, only one set of three phases was shown, but
Even if a high-voltage insulation resistance measuring device is installed in each phase to measure the insulation resistance between the three phases, the desired effect can be achieved.

As described above, by using the high voltage switchgear of the present invention, the insulation resistance measurement of AC high voltage equipment, high voltage cables, etc. can be performed safely and easily with a simple configuration, and since it uses a rectifying element and a resistor, This means that alternating current is rectified into direct current, and even if you touch the measurement terminal while it is energized, the current flowing through your body becomes direct current with a half-wave rectified waveform, making it safer. Therefore, the present invention is extremely useful in today's world where eradication of industrial accidents and labor saving are in demand.

[Brief explanation of the drawing]

The drawing shows a circuit diagram of electrical equipment incorporating the high voltage switchgear of the present invention. In addition, 1 is a high voltage switchgear, 2
-1, 2-2, 2-3 are main circuit primary terminals, 3-
1, 3-2, 3-3 are main circuit secondary terminals, 4 is a rectifier, 5 is a resistor, 6 is a lead-out terminal for measuring insulation resistance, 7-1, 7-2, 7-3 are high voltage cables core wire, 8 is high voltage equipment, 9-1, 9-2, 9-3 are internal secondary circuits of high voltage switchgear, 10-1, 10-
2 and 10-3 indicate connection terminals of high-voltage equipment, respectively.

Claims (1)

[Scope of Claim for Utility Model Registration] A high voltage switchgear that connects a secondary circuit made of a high voltage cable to a high voltage device and switches on and off an alternating current high voltage current supplied to the high voltage device, comprising: In addition to providing a lead-out terminal for insulation resistance measurement in which a rectifying element and a resistor are connected in series with a high-voltage insulated wire from the main circuit secondary terminal,
The high-voltage switchgear is characterized in that the rectifying element is connected in series with the resistor so as to be in a forward direction when viewed from the lead-out terminal, and the current flowing through the lead-out path is set to 20 mA or less using the resistor. .