BACKGROUND

[0001] The present inventions relate generally to inspecting fluid-filled containers, and more particularly, to accessing the interior of the container through a side port.

[0002] One type of fluid-filled container that requires regular inspection is high voltage transformers filled with oil. Other types of fluid-filled containers that also require internal inspection include nuclear plants, portions of ship hulls, etc. In the case of high voltage transformers, conventional inspection techniques can be difficult and expensive. For example, the oil in the transformer is typically drained out and temporarily stored in a storage tank. The amount of oil that must be drained and stored can be as much as 30,000-40,000 gallons. After draining the transformer, a human inspector crawls into the interior of the transformer through an access port. Once inside, the inspector views the components of the transformer, performs tests, and captures images of the transformer components, etc. This can be dirty, time- consuming, challenging and possibly hazardous work for an inspector.

[0003] It has been proposed that transformer inspections could be done easier, cheaper and safer by using submersible robots. In this alternative, a submersible robot is placed within the transformer without draining the oil from the transformer. The robot then travels through the oil with fluid thrusters or the like to move around the transformer components inside of the transformer. The robot may be equipped with various sensors to inspect the equipment and report back to the inspection operator. For example, the robot may carry a camera to capture images of the transformer components.

[0004] Although submersible robots have the potential to significantly improve inspection techniques of transformers and other fluid-filled containers, access into the interior of the container has been envisioned as occurring through a top port of the container. That is, since the oil remains in the transformer without being drained therefrom during inspection, the most direct way to introduce the robot into the transformer is to open a port at the top of the transformer to gain access above the level of the oil therein. The robot can then be lowered into the oil through the top port without the oil spilling out of the transformer. [0005] However, some transformers are not provided with a top port for accessing the interior of the transformer. Instead, these transformers typically have a port on the side of the transformer below the level of the oil therein. While such designs are completely compatible with conventional inspection techniques that involve draining the oil from the transformer prior to inspection, special arrangements are needed to open the side port of a fluid-filled container for the introduction of a submersible robot while preventing the fluid therein from escaping through the open side port.

SUMMARY

[0006] An access chamber is described for introducing a submersible robot through a side port of a fluid-filled container without draining the fluid from the container. The access chamber is connected to the side port to provide fluid communication between the side port and the access chamber. The access chamber is then filled with fluid before the side port is opened. After the access chamber has been filled with fluid and the side port opened, the submersible robot moves through the side port from the access chamber to enter the container.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0007] The invention may be more fully understood by reading the following description in conjunction with the drawings, in which:

[0008] Figure 1 is a cross-sectional view of a transformer and an access chamber;

[0009] Figure 2 is a side view of the access chamber;

[0010] Figure 3 is a cross-sectional view of a first stage of introducing a submersible robot through a side port of the transformer;

[0011] Figure 4 is a cross-sectional view of a second stage of introducing the submersible robot;

[0012] Figure 5 is a cross-sectional view of a third stage of introducing the submersible robot;

[0013] Figure 6 is a cross-sectional view of a fourth stage of introducing the submersible robot;

[0014] Figure 7 is a cross-sectional view of a fifth stage of introducing the submersible robot; and [0015] Figure 8 is a cross-sectional view of a sixth stage of introducing the submersible robot.

DETAILED DESCRIPTION

[0016] Referring now to the figures, and particularly Figure 1 , a transformer 10 is shown. It is understood that while the description herein principally involves a high- voltage transformer 10, it is possible that the described inventions could be applied to other types of inspections as well, such as nuclear power plants, ship hulls, etc. The transformer 10 includes a container 12, or tank 12, that surrounds the internal components, including cores 14 and windings 16. On top of the container 12 are connection terminals 18 surrounded by insulating bushings 20 for connecting the power supply and power output cables 22. Although not shown in detail, but understood in the art, the connection terminals 18 are interconnected inside the container 12 to the transformer windings 16. Inside the transformer 10, the container 12 is filled with a fluid 24, such as oil 24 (e.g., mineral oil 24), to insulate, cool and preserve the internal components 14, 16 of the transformer 10.

[0017] On a regular basis it is necessary to inspect the internal components 14,

16 of the transformer 10. For example, heat damage, corrosion or other such conditions are important to identify before an actual failure of the transformer 10.

One solution for inspecting the components 14, 16 inside the container 12 of the transformer 10 is a submersible robot 26 (see Figure 8) which may use fluid thrusters to navigate through the oil 24 inside of the container 12. The submersible robot 26 may be provided with various sensors for collecting inspection information about the components 14, 16 inside the container 12. For example, it may be useful to provide the robot 26 with a camera for capturing images of the transformer components 14, 16.

[0018] Although various types of transformers 10 exist, the presently described transformer 10 has no access ports on the top of the transformer container 12. It is understood, for example, that the bushings 20 are not considered to be potential access ports even though there is a removable connection between the bushings 20 and the container 12. That is, the bushings 20 are connected to the internal components 16 and are also connected to the power cables 22, such that disassembly of the bushings 20 would be undesirable. Instead of having a top access port, the transformer 10 is provided with a side port 28. That is, the side port 28 is located below the level 30 of the fluid 24 inside of the container 12. Typically, the side port 28 is located along the lower half of the container 12, and most commonly, in the bottom quarter of the container 12.

[0019] In order to introduce a submersible robot 26 into the container 12 through the side port 28 without draining the fluid 24 out of the transformer 12, an access chamber 32 is connected to the side port 28 to provide fluid communication between the side port 28 and the interior of the access chamber 32. Various types of connections may be made, but in the present embodiment, and as shown in

Figure 3, the access chamber 32 is provided with an opening 34 through one side wall of the chamber 32. The opening 34 is sized to allow the opening 34 to slide over the side port 28 and the side port 28 to pass therethrough. Where the side port 28 has a flange 36 at the end of a pipe 38 and a cover 40 attached to the flange 36, the opening 34 may be sized larger than the flange 36. As will be understood, the access chamber 32 must be sealed around the side port 28 to prevent oil 24 from draining from the access chamber 32. In the present embodiment, this may be achieved with a flexible sleeve 42, or first sleeve 42, attached around the opening 34. The flexible sleeve 42 may be cinched around the pipe 38 with a pipe clamp, zip tie or the like 44. If desired, the sleeve 42 may be accessed to cinch it through the access opening 46 at the top of the chamber 32.

[0020] After the access chamber 32 has been connected to the side port 28, it may be desirable to place a bushing 48 (Figure 3) between the side wall of the access chamber 32 and the backside of the flange 36 so that the access chamber 32 engages the backside of the flange 36. It is also possible for the wall of the chamber 32 to be designed to directly contact the backside of the flange 36. Such

engagement may be useful to counter the pressure of the fluid 24 in the container 12 when the cover bolts 50 are removed. However, it is also possible for the weight of the access chamber 32 to resist the pressure or for the access chamber 32 to be anchored to the ground. Alternatively, it may be possible to remove the bolts 50 after the access chamber 32 has been filled with fluid 52 to reduce the need for anchoring.

[0021] As shown in Figure 3, a restraining member 54 may be pressed against the side port cover 40 to hold the cover 40 in place after removal of the cover bolts 50. This preferably occurs before the access chamber 32 is filled with fluid 52. As shown in Figure 4, the cover bolts 50 may then be removed after the restraining member 54 has been pressed against the cover 40 and before the chamber 32 is filled with fluid 52. Various types of restraining members 54 may be used. However, in the preferred embodiment, the restraining member 54 may be the end portion of a piston 56 of a hydraulic cylinder 58. More preferably, the hydraulic cylinder 58 is attached to the side wall of the chamber 32 opposite from the chamber opening 34 for the side port 28. It may also be desirable for the restraining member 54 to have a magnet 60 at the end thereof for engaging the cover 40. Thus, after the piston 56 is moved against the cover 40 and the magnet 60 contacts the cover 40 (Figure 3), the bolts 50 may be removed from the side port and the piston 56 may be retracted away from the side port 28 (Figure 7). As a result, the cover 40 is moved away from the side port 28 with the piston 56 in order to open the side port 28. Although it may be possible for the hydraulic cylinder 58 to be located within the interior of the access chamber 32, in the preferred embodiment the hydraulic cylinder 58 is outside the chamber 32. The piston 56 then extends through the wall of the chamber 32 to engage the side port cover 40. A second seal 62 is also provided in the wall around the piston 56 to prevent oil from leaking from the access chamber 32.

[0022] Referring to Figures 3 and 4, after the restraining member 54 has been pressed against the cover 40, the cover bolts 50 may be removed by reaching into the chamber 32 through the top access opening 46. It may also be desirable at this stage (before filling the chamber 32) to mount a wireless communication antenna 64 (e.g., Wi-Fi, Bluetooth) inside of the chamber 32 near the side port 28 (e.g., on the flange 36). As shown in Figure 2, it may be desirable for a portion of the chamber 32 to have a transparent wall 66 in order to be able to see inside of the chamber 32 when moving the restraining member 54, engaging the cover 40, navigating the robot 26, etc. For example, the top half of the chamber 32 could be made of transparent plastic 66. For durability, the bottom portion 68 could be metal 68.

[0023] Referring to Figure 5, after the cover 40 has been engaged with the restraining member 54 and the bolts 50 removed, the access chamber 32 may be filled with fluid 52. Preferably, the fluid 52 is compatible with the fluid 24 within the container 12 of the transformer 10 and may be a matching type of fluid.

[0024] As shown in Figure 6, a duct 70 may then be attached to the access opening 46 of the chamber 32, and the duct 70 may also be filled with fluid 72. It is understood that the access chamber 32 and duct 70 may both be filled with oil 52, 72 at the same time after the duct 70 has been attached. However, it is believed that filling the chamber 32 and the duct 70 in two separate steps may be preferred to minimize the introduction of air bubbles in the fluid 52, 72, which can be a problem if any air bubbles pass into the interior of the transformer container 12. It is also understood that the access chamber 32 could be provided with an integral duct that is not separable therefrom. However, it is believed that it will be easier to use the access chamber 32 with the access opening 46 being provided (e.g., accessing the bolts 50, mounting the antenna 64).

[0025] As shown in Figure 6, the duct 70 extends upward so that the top opening 74 of the duct 70 is above the level 30 of the fluid 24 in the transformer container 12. It may be desirable for the duct 70 to have one or more bends 76 that bend away from the transformer container 12 to provide clearance for various structures that may be attached to the outside of the container 12. Once the duct 70 is installed, the duct 70 may be filled with fluid 72, which again is preferably compatible with the transformer fluid 24 and may match the transformer fluid 24. The fluid 52, 72 in the duct 70 and access chamber 32 may be filled so that the level 78 of the fluid 52, 72 in the duct 70 and access chamber 32 is equivalent to or above the level 30 of fluid 24 in the transformer container 12. As shown in Figure 7, the restraining member 54 may then move the cover 40 away from the side port 28 to open the port 28. An advantage of filling the duct 70 to the level 30 of the transformer fluid 24 or above is that the fluid 24 in the transformer 10 does not drain out of the side port 28 due to the fluid pressure of the fluid 52, 72 in the access chamber 32 and the duct 70. It is understood that it is possible for the transformer 10 to be provided with an expansion tank or other auxiliary oil storage compartment in fluid communication with the interior of the transformer tank 12. If the level of transformer fluid 24 in such auxiliary storage is above the top of the tank 12, the level 30 of the transformer fluid 24 would necessarily be determined by such auxiliary storage.

[0026] As shown in Figure 8, after the access chamber 32 and duct 70 have been filled with oil 52, 72 and the side port 28 opened, the submersible robot 26 may be introduced through the top opening 74 of the duct 70. Fluid thrusters or other propulsion systems may then be used to move the robot 26 down through the duct 70, the access opening 46, the access chamber 32, the side port 28, and finally into the transformer container 12. Once in the transformer container 12, the robot 26 performs inspection of the internal components 14, 16 of the transformer 10 and may capture images or perform other tests. Communication with the robot 26 (including navigation and/or image retrieval) may be performed through the antenna 64 in the access chamber 32. After inspection is complete, the robot 26 may be navigated out of the transformer container 12 through the side port 28, and the steps described above may be reversed to close the side port 28 and remove the access chamber 32 from the site. As shown in Figure 2, a drain port 80 may be provided at the bottom of the access chamber 32 to drain the oil 52, 72 from the access chamber 32 and the duct 70 after the inspection has been completed.

[0027] While preferred embodiments of the inventions have been described, it should be understood that the inventions are not so limited, and modifications may be made without departing from the inventions herein. While each embodiment described herein may refer only to certain features and may not specifically refer to every feature described with respect to other embodiments, it should be recognized that the features described herein are interchangeable unless described otherwise, even where no reference is made to a specific feature. It should also be understood that the advantages described above are not necessarily the only advantages of the inventions, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment of the inventions. The scope of the inventions is defined by the appended claims, and all devices and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.