JPS6132883B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulating structure composed of a composite of an air layer and an insulating partition wall for electrical equipment.

Examples of electrical equipment that often uses this type of insulation structure include switchboards, where bare live parts such as busbars and terminals of internal electrical components are connected between different poles, between the same poles across open poles, and between bare live charging parts. It is well known that the switchboard is used between the switchboard and the ground to reduce the size of the switchboard itself. However, in such an insulating structure, since the partition wall is an insulator, it is charged by the commercial power supply voltage during operation, and the partition wall has a potential. Therefore, if this potential is high, voltage detectors used to confirm safety during maintenance inspections may light up, and even if electrical safety has been proven, final safety cannot be confirmed. There is. This means that for insulation structures such as switchboards, which are required to ensure insulation against commercial power voltage as well as impulse voltages such as lightning surges, designs are planned based only on the values of both voltages, and the difference in frequency, i.e. For example 50 for power supply
Hz, 60Hz and approximately 10kHz in the case of impulse voltage were not taken into consideration, resulting in the residual charge from the low frequency commercial power supply. Here, the frequency of the impulse voltage is
The reason for setting Vi to approximately 10kHz is that the standard waveform of 1 x 40μs in the impulse voltage becomes 0.85Vp after 10μs from the wave front value Vp during its attenuation process, so this period is replaced by a sine wave angular change33 It is calculated using the following formula as °, and is a commonly used numerical value.

Vi=1(Sec)/10(μs)× ^10-6 ×33 ⁽
Γ ⁾ /360 ⁽ Γ ⁾ ≒10 (kHz) And for the switchboard, the International Electrotechnical Commission (IEC)
In Japan, design conditions and verification methods are stipulated in terms of safety for the human body, and safety can be confirmed using simple means such as a voltage detector without increasing the thickness of the air layer or bulkhead. The development of an insulating structure has been long awaited.

In view of the above, it is an object of the present invention to provide an insulating structure that ensures impulse voltage withstand characteristics, lowers the potential of charges charged on insulating partition walls by commercial power during operation, and proves safety and is inexpensive. shall be.

According to this invention, the above-mentioned purpose is achieved by combining an air layer and an insulating partition provided between bare live parts of different polarities, between bare live parts of the same polarity sandwiching an open contact part, and between a bare live part and the ground. In the insulating structure configured to ensure insulation between the impulse voltage and the commercial power supply voltage, the insulating partition wall is sandwiched between two insulating plates and a high-resistance thin material that is closely attached to each insulating plate and grounded. This is achieved by changing the voltage sharing between the impulse voltage and the commercial power supply voltage.

Embodiments of the present invention will be described below based on the drawings. First, the principle will be explained with reference to Figures 1 to 3. In Figure 1, there is a lower electrode 2 that is connected to the upper electrode 1 and is grounded. A partition wall 3 in which resistors R having . According to the present invention, since there is a frequency difference of about 200 times between the commercial power supply and the impulse voltage as mentioned above, the insulation structure is constructed such that the upper electrode 1 or the lower electrode 2 and the insulation partition wall change depending on this frequency difference. This takes advantage of the fact that the voltage polarity changes between the impulse voltage Vi and the commercial power supply voltage Va due to the impedance of the stray capacitance C between be. The relationship is shown in FIG. In Figure 3, the distance I between the electrodes 1 and 2 in Figure 1 is taken on the vertical axis, and the voltage V is taken on the horizontal axis, and an impulse voltage or commercial voltage having a predetermined voltage value Vm is applied between the electrodes 1 and 2 It shows the voltage change at each position between electrodes 1 and 2 when the voltage is applied. The curve in FIG. 3 shows the voltage distribution of a conventional insulation structure in which the resistor R is not provided on the partition wall 3, and the voltage at the position I ₃ where the partition wall 3 is provided is when an impulse voltage is applied and The same V ₃ is obtained in both cases when the commercial power supply voltage is applied. The curve , corresponding to this, shows the voltage sharing when a resistor R is added to the partition wall 3, the curve shows the voltage sharing when an impulse voltage is applied, and the curve shows the voltage sharing when a commercial power supply voltage is applied. As is clear from this, the bulkhead 3 was installed.
The voltage at the position I ₃ has different values from V ₂ and V ₁ , respectively. The voltage sharing value of the partition wall 3 is high when an impulse voltage is applied and becomes low when a commercial voltage is applied, and this value can be adjusted by selecting the value of the resistor R. Therefore, according to the present invention, it is possible to keep the voltage sharing value V ₁ low with respect to the commercial power supply voltage Va that is charged during operation and becomes the detection voltage while ensuring the impulse withstand voltage.

Note that I ₁ on the vertical axis of FIG. 3 indicates the position of electrode 1 in FIG. 1, and I ₂ indicates the position of electrode 2.

Next, one embodiment of the present invention will be explained with reference to FIG. The diagram corresponds to the above-mentioned principle establishment,
This is an insulating structure between live parts of the same polarity that sandwich the opening part. A busbar room 1 partitioned above a switchboard 11 having a side-by-side configuration, only a portion of which is shown in the figure.
2, a three-phase busbar 13 corresponding to the above-mentioned upper electrode 1 is disposed so as to penetrate between the rows of boards, and is supported by an insulating support 14 attached to the inner wall of the busbar chamber 12. . The insulating support 14 has power supply side disconnecting contacts 15 connected to the three-phase bus 13 for each phase.
are integrally provided. A load-side disconnection contact 16 is arranged below the busbar chamber 12 and is connected to a load supported by a support (not shown).
The power supply side disconnection contact 15 and the load side disconnection contact 16 each have a disconnection contact 17 that can be connected to and separated from them.
A drawer type with 18 and a disconnector 19 are connected. On the other hand, an insulating partition wall 20 corresponding to the above-mentioned insulating partition wall 3 is disposed between the three-phase bus bar 13 and the load-side disconnection contact 16 in the bus bar chamber 12 to ensure insulation therebetween. The insulating partition wall 20 is composed of two insulating plates 21 made of, for example, phenol resin, and a high-resistance thin film 22 coated with, for example, graphite-mixed varnish, which is sandwiched between them. The material should preferably have a surface resistance of 10 ⁶ Ω to ^{10 8} Ω, since the normal capacitance between a bare live part such as the bus bar 13 and a resistive surface such as the high-resistance thin film 22 is from several pF to several 100 pF. In addition to the above-mentioned materials, examples of such materials include paper mixed with graphite or carbon, and materials in which metal is vapor-deposited or ionomer bonded to a film. In this case, the partition wall 20 was constructed by sandwiching the high-resistance thin film 22 between two insulating plates 21, but this is because the high-resistance thin film is based on paper or film and is mechanically weak. This was done because it is vulnerable to arc heat in the unlikely event of an internal flash fault, and it is clear that there is no need to worry about it when only voltage sharing is considered. Therefore, it is natural that if one side is a grounded side wall or an inspection passage and there is no risk of mechanical damage or burnout, the insulating plate on that side can be omitted. In this way, 1
When a partition wall is made up of two insulating plates and a high-resistance thin film, it is difficult to adjust the resistance value. It's okay.

As described above, according to the present invention, the insulating partition wall can act like a ground plate for the commercial power supply voltage and as an insulating partition wall for the impulse voltage. Since the electrical potential charged by the voltage drop is lowered, the voltage detector does not light up, eliminating concerns during safety confirmation.Furthermore, since only a high-resistance thin film is added, it can be manufactured at low cost.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram for explaining the insulation structure of the present invention, Fig. 2 is a diagram showing the equivalent circuit of Fig. 1, Fig. 3 is a diagram showing the voltage division of Fig. 1, and Fig. 4 is a diagram showing the voltage division of Fig. 1. 2 is a cross-sectional view of an example insulation structure based on FIG. 1; FIG. 13... Three-phase bus bar (bare live part), 16... Load side disconnection contact (bare live part), 20... Insulating partition, 21... Insulating plate, 22... High resistance thin film.

Claims (1)

[Claims] 1 Composite construction of an air layer and an insulating partition wall provided between bare live parts of different polarities, between bare live parts of the same polarity, and between bare live parts and ground, ensuring insulation between impulse voltage and commercial power supply voltage. In the insulating structure, the insulating partition wall is composed of two insulating plates and a high-resistance thin film sandwiched between them and closely attached to each insulating plate and grounded, and the impulse voltage and the commercial power supply voltage are equal to each other. An insulating structure for electrical equipment, characterized in that the roles are changed.