JPS5926584Y2 - oil-filled electrical equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to dual-rated oil-filled electrical equipment using the oil natural circulation cooling method and the oil feeding cooling method, and particularly relates to an improvement of the cooler piping drawing structure.

In dual-rated oil-filled electrical equipment with natural oil circulation cooling and oil feed cooling, an oil feed pump is inserted in series with the oil flow system during natural oil circulation.

The oil circulation force during natural oil circulation is very weak, and when the oil passes through the oil feed pump in the oil flow system, it suffers a lot of pressure loss, which reduces the oil circulation force and the required oil flow rate is insufficient. Resulting in.

To compensate for this, as shown in Fig. 1, check valves 4 are installed in parallel with the oil feed pump 3 installed between the oil-filled electrical equipment main body 1 and the cooler 2 at an angle θ. There is one that configures the route.

That is, the cooler 2 is disposed at a position slightly higher than the oil-filled electrical equipment body 1, and the upper end of the cooler 2 and the upper part of the oil-filled electrical equipment body 1 are connected by a common drawing 5.

A common lottery 6 is provided horizontally in the lower part of the cooler 2, and a lottery 7a is provided horizontally in the lower part of the oil-filled electrical equipment main body 1.

Further, the oil pump 3 is attached to this lottery 7a, and a lottery 7b extending vertically upward from the oil pump 3 is connected to the common lottery 6.

Further, a lottery 8 is provided at the bottom of the oil-filled electrical equipment 1, and this lottery 8 and the common lottery 6 are communicated via the check valve 4.

The cooler 2 is located at a high position, and the lottery on the oil pump 3 side is guided vertically downward with respect to the lottery 6, so the check valve 4
By arranging the insulating oil at an angle of θ with respect to this, the insulating oil flowing down from the cooler 2 flows to the lower side of the oil-filled electrical equipment main body 1 using the head, and when there is an upward flow, this is blocked and the oil is natural circulation cooling with less pressure loss.

FIG. 2 is a sectional view showing details of the check valve 4.

In the figure, 4a is an outer casing, 4b is a valve seat provided in the outer casing 4a, and 4C is in close contact with a valve seat 4b whose upper end is pivotally supported by a pin 4d and rotated counterclockwise from the bottom side of the figure. It is a valve body that closes the circuit, and when the oil pressure is weak and naturally circulates, the solid line arrow A
This check valve 4 is installed on the vertical axis in order to pass the insulating oil in the downward direction shown by with as little hydraulic loss as possible, and to reliably prevent the upward flow shown by the dotted arrow B. The structure is such that it is installed at an angle of θ as shown in the figure.

Note that 4e is a flange. Therefore, such a check valve 4
By providing the valve body 4C with an inclination of θ in parallel with the path of the oil feed pump 3, the valve body 4C hangs vertically downward due to gravity, and the valve is normally in an open state.

Therefore, although the resistance in the check valve 4 is small, during natural circulation, the insulating oil flows along the path of the check valve 4, avoiding the oil feed pump 3 side where the resistance is large.

On the other hand, since the oil pump 3 is driven during oil cooling, the insulating oil sent from the oil pump 3 is forcibly fed into the main body 1 of the oil-rich electrical equipment.

At the same time, since the hydraulic pressure is large, a part of the insulating oil that has flowed into the oil-filled electrical equipment main body 1 flows back toward the check valve 4, but due to this back flow, the valve body 4C is rotated counterclockwise, and the valve body 4C is rotated counterclockwise. A closed circuit is formed in close contact as shown by the dotted line.

This prevents backflow.

Therefore, all of the oil flow from the oil pump 3 enters the oil-filled electrical equipment main body 1 and flows to the cooler 2 after being internally cooled.

By the way, since the check valve 4 is opened and closed by hydraulic pressure, when the oil pump 3 is started, it closes due to the large pressure backflow, so the valve body 4C hits the valve seat 4b with a strong impact, causing a large impact. generate sound.

Further, if the oil flow pressure is low, the valve will not close completely, and when the oil flow pressure fluctuates due to fluctuations in the pump power supply voltage, etc., vibrations may occur between the valve body 4C and the valve seat 4b.

Furthermore, since there is a movable part called the valve body 4C and it is subjected to strong impact, there is a concern that this movable part may become loose due to aging.

The present invention was developed in view of the above circumstances, and is rated for both natural oil circulation cooling method and oil feed cooling method, and has bypass piping for oil natural circulation installed in parallel with the oil pump piping. By attaching to the bypass piping a double-pipe orifice having an outer pipe with a constant diameter and an inner pipe with a smaller diameter along the oil flow direction during natural oil circulation inside the outer pipe, To provide an oil-filled electrical device which eliminates the drawbacks, effectively prevents backflow when oil is fed by an oil pump, does not generate noise when backstopped, and does not deteriorate over time.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 3 is a sectional view showing the structure of a double-pipe orifice 30 used in place of the check valve 4 conventionally connected to a bypass piping section provided in parallel to the thread path of the oil feed pump 3. In the figure, numeral 31 is an outer tube of equal diameter with flanges 31a provided at both ends, and numeral 32 is an inner tube provided within this outer tube 31.

This inner tube 32 has one end fixedly attached to the inner wall of the outer tube 31, and the other end left in a free state.

The other end, ie, the free end, has a smaller diameter than the fixed end, and is formed, for example, in the shape of a funnel, and the wall thickness on the free end becomes thinner toward the tip.

In addition, the free end side should have a diameter sufficient for the oil flow rate required during natural oil circulation.

In the orifice 30 having such a configuration, the inflow from the free end side of the inner tube 32, that is, the direction of the dotted arrow B, is the check direction, and the inflow from the fixed end side, that is, the direction of the solid line arrow A, is the forward direction.

The opening on the free end side of the orifice 30 has a diameter sufficient for the flow rate for forward flow, and the diameter gradually becomes narrower for the flow, so it is suitable for natural circulation flow with low resistance and weak pressure. However, there is almost no pressure loss and the natural circulation flow is not disturbed.

However, for reverse flow (flow in direction B), a large pressure loss occurs because the flow collides with the free end side of the inner tube 32 having a small diameter from the wide outer tube 31.

Such an orifice 30 is connected in the forward direction between the drawings 6 and 8, which are bypass piping, in place of the check valve 4 of the apparatus shown in FIG.

In this way, during natural oil circulation, the insulating oil flows in the direction of arrow A, which is the natural circulation oil flow direction, so the internal cross section of the orifice first acts as a kind of reducer, and then, after rapidly expanding the cross section, it moves to Lottery 8. Insulating oil leaks.

For the pressure loss due to oil flow, the pressure loss is the coefficient ζ, and the speed is V
(cm/5ec), gravitational acceleration g = 980 (cm
/5ec2), approximately ζ×! It can be expressed as

(g) When the diameter of the outer tube 31 of the orifice 30 is made twice the diameter of the inner tube 32, the pressure loss coefficient ζ of the double tube orifice having the shape as shown in FIG. 3 is about 0.6.

Comparing the pressure loss coefficients in the oil feed pump 3 and the double-pipe orifice 30, and designing the double-pipe orifice 30 to have a sufficiently lower value, most of the oil flow will flow to the bypass piping side. The oil will flow into the oil-filled electrical equipment 1 through the provided double-pipe orifice 30, and if the inner pipe 32 of the double-pipe orifice 30 is set to have a sufficient opening diameter for oil natural circulation. Natural circulation can be carried out without any hindrance.

On the other hand, when oil is fed by driving the oil feed pump 3, the insulating oil discharged from the oil feed pump 3 is once sent into the oil-filled electrical equipment main body 1.

The oil is then sent to the cooler 2 through the draw 5, which is a cooler piping at the top of the oil-filled electrical equipment main body 1, but a portion flows back to the orifice 30 via the draw 8, which is a bypass pipe.

The direction of flow into this double-tube orifice 30 is the B direction in FIG. 3, and as described above, the orifice 30 exhibits high resistance to the reverse flow in the B direction.

Therefore, the pressure loss coefficient ζ within the orifice 30 is very large, and is 10 or more.

Therefore, the insulating oil flowing back through the orifice 30 suffers a pressure loss determined by the above-mentioned pressure loss coefficient.

Therefore, due to the oil flow during oil transfer, the main body of electrical equipment 1 → cooler 2
→ Pressure loss in the system of oil-filled electrical equipment 1 → Oil-filled electrical equipment 1 → Oil pipe 8 → Orifice 30 → Oil-filled electrical equipment 3 → Oil-filled electrical equipment main body 1 If the value is set to a sufficiently small value in comparison, most of the oil flow will flow to the system of oil-filled electrical equipment main body 1 → cooler 2 → oil feed pump 3 → oil-filled electrical equipment main body].

Although it is not possible to completely prevent the oil flow from flowing backward through the double-pipe orifice 30, the amount is small, and although it enters the oil-filled electrical equipment main body 1 via the oil feed pump 3 without being cooled, the oil temperature remains low. It has little effect on the rise.

In this way, in oil-filled electrical equipment equipped with both the oil natural circulation cooling method and the oil feed cooling method, a bypass pipe is installed in parallel with the oil feed pump, and a double pipe orifice is installed in this bypass pipe to suppress backflow. Since this bypass piping route is used as a route for natural oil circulation, during natural oil circulation, the bypass piping route allows cooling by natural circulation without any problems with almost no pressure loss. In some cases, the orifice can suppress backflow due to oil supply, allowing each of the two cooling methods to be used effectively.In addition, a double pipe orifice is used to suppress backflow, so there are no moving parts, so there is no rattling due to aging. Furthermore, it is possible to provide an oil-filled electrical device having a drawing structure that is inexpensive and stable in operation, without vibrations or impact noises caused by unstable operation due to oil pressure fluctuations.

The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof. In particular, the structure of the double-pipe orifice is shown in Fig. 3. It is not necessary that the inner tube has a funnel-like shape as shown, but it is sufficient that the inner tube has a different diameter so that the pressure loss varies greatly depending on the oil flow direction.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the configuration of oil-filled electrical equipment, Figure 2
The figure shows the structure of a conventionally used check valve, and FIG. 3 shows the structure of a double pipe orifice used in the device of the present invention. 1...Oil-filled electrical equipment body, 2...Cooler, 3...Oil pump, 5, 6, 7 a, 7
b, 8... Lottery, 30... Orifice, 31... Outer tube, 32... Inner tube.

Claims (1)

[Scope of utility model registration request] In oil-filled electrical equipment equipped with three methods: oil natural circulation cooling method and oil feeding cooling method, a bypass pipe line is provided in parallel to the pump line that sends oil to the oil-filled electrical equipment main body by the cooler,
An oil-filled electrical device characterized in that an orifice is provided inside the conduit with an orifice whose diameter changes from small to small along the oil flow direction to serve as a flow path during oil natural circulation cooling.