Patent Description:
A cable carousel, also known as a cable turntable, is a horizontal disc used for storing large lengths of cable during and after cable production, and during cable laying. The cable is typically optical fibre cable or electrical cable. A cable carousel is driven for rotation about a vertical axis. This can be achieved by the cable carousel having several wheels which run along circular horizontal rails on the ground, much like a railway. At least some wheels may be driven. Cable carousels can be large constructions, the biggest having a diameter of <NUM> metre and a capacity of <NUM> tonnes cable.

This conventional cable carousel has the drawback that it is expensive to build. Another drawback is that the wheels are driven by electric motors on the carousel, which means that electrical power must be transferred to the carousel by sliprings, which complicates the use of the carousel. A further drawback is that the operational reliability is lower than desirable. High operational reliability is very important, since an interruption of operation may lead to cable breakage with large economic consequences. A still further drawback is the large loading of the ground by the rails, which necessitates an extensive foundation for the rails.

Document <CIT>, entitled "Carrousel with water bearing", is considered to be comprised in the state of the art pursuant to Article <NUM>(<NUM>) EPC and discloses cable turntable assembly for use in storing and laying long lengths of pipe or cable, comprising: a rotatable turntable; a turntable support surface supporting the turntable for rotational movement; and a fluid bearing system between the rotatable turntable and the turntable support surface, the fluid bearing system comprising a pressurized fluid chamber and a sealing system comprising a sealing element extending at a circumference of the turntable to seal an annular gap at the outer circumference of the turntable.

Document <CIT> discloses a hydraulic rotatory and translatory device. Document <CIT> discloses an apparatus with a floating tank for taking-up of a cable.

Further relevant prior art is disclosed in documents <CIT> (providing a cable delivering device of a ship) and <CIT> (regarding a floatable spool apparatus).

The purpose of the invention is to solve or reduce at least one of the above problems, or at least provide an alternative to prior art.

The purposes of the invention are achieved by an apparatus according to claim <NUM>, and a method according to claim <NUM>. Further features, advantages and purposes of the invention and how they are achieved will appear from the description, the drawings and the claims.

The invention thus relates to an apparatus for storing cable, comprising a cable carousel rotatable about a vertical axis; and rotating means for rotating the carousel about the vertical axis, for allowing winding cable on the carousel and unwinding cable from the carousel.

Rotatability about the vertical axis may be provided by a radial bearing or by external, stationary, horizontal wheels arranged along the circumference of the carousel for securing the carousel laterally while allowing rotation. Rotating means for rotating the carousel about the vertical axis may be a belt, wheels or gears cooperating with the carousel.

According to the invention the carousel is received in a pool defined by a bottom and an outer wall. Further a seal is arranged in a pool gap between an outer side of the carousel and the pool outer wall. Portions of the carousel below the seal is liquidtight, and the seal, the portions of the carousel below the seal, the pool bottom, and the pool outer wall thereby define a closed chamber. Pressurised liquid in the closed chamber provides a positive pressure for supporting the carousel and allowing rotation of the carousel.

The pool may be made in any way. The pool bottom may be made from concrete or comprise a liquidtight membrane arranged on a foundation. "Liquidtight membrane" shall mean any kind of liquidtight foil, canvas, web or fabric. "Outer wall" shall mean any means that defines the pool. The seal may be attached to the carousel, and slide against the pool outer wall. The seal may be located at the edge of a carousel floor, and to provide the closed chamber, the carousel floor must then be liquidtight. Alternatively, the seal may be located on the carousel outer wall, and then the carousel floor as well as the carousel outer wall below the seal must be liquidtight to provide the closed chamber. In another embodiment the seal may be attached to the pool outer wall, and slide against the carousel. In this case, the carousel floor and the carousel outer wall below the seal must be liquidtight to provide the closed chamber. The seal must seal during sliding and endure long-term use, and may be made from rubber. Pressurised liquid may be supplied from a pump or from an external source. Preferably means for regulating a supply of pressurised liquid to the closed chamber and removal of liquid from the closed chamber regulates an elevation of the carousel. The apparatus comprises hold-down means for holding down the carousel, to keep the carousel horizontal.

The invention also relates to a method for constructing the carousel and the pool according to the invention. In this method the carousel is fabricated in sections, typically from steel plates that are welded together. This can be done in a factory, which typically is not located at a construction site where the carousel is to be used. Further, according to the method of the invention, the pool is constructed at the construction site. The pool may be constructed of concrete, but other ways of constructing the pool are possible, e.g. making the outer wall from a self-supporting steel ring with a lower portion supported by the ground, and using a liquidtight membrane as the bottom. After the pool is constructed, the items for centring, driving, holding-down and levelling the carousel as well as valves, required tubes or hoses and instruments, are mounted. The carousel sections are then arranged in the pool, which is typically done by means of a lifting crane. The carousel sections are then assembled to form the carousel, which is typically done by placing gaskets between the sections and bolting them together. After the carousel is completed, pressurised liquid is filled in the pool, which lifts the carousel above the pool bottom. The operation of the apparatus according to the invention can then start.

The carousel sections will probably be fabricated by a different contractor than the pool.

The invention will now be described with reference to the accompanying drawings, in which:.

<FIG> is a cutaway perspective view of a cable carousel <NUM> for storing cable according to the invention, seen obliquely from above. Cable carousel <NUM> is composed of sections <NUM> which are welded steel constructions mainly made of plates. Sections <NUM> have upper and lower sides with the shape of a sector of a circle, and are held together by not illustrated bolts through bolt holes <NUM> in their lateral sides, as seen for the rightmost section <NUM>. The leftmost section <NUM> is radially cut through, and therefore no bolt holes are seen in this section. Together the cable carousel sections <NUM> form a carousel floor <NUM>, a carousel top <NUM> and a carousel outer side <NUM>. Gaskets between sections <NUM> ensure that at least carousel floor <NUM> is liquidtight. A coil of cable <NUM> is held in place on carousel top <NUM> by vertical posts <NUM> secured to carousel top <NUM>. Cable <NUM> can be passed to and from carousel <NUM> via a guide arm <NUM> not forming part of the invention.

Carousel <NUM> is received in a pool <NUM> which is circular about a vertical axis <NUM>. Pool <NUM> is defined by a concrete bottom <NUM> and an outer steel wall <NUM>. Pool outer wall <NUM> faces carousel outer side <NUM>, and a pool gap <NUM> is defined between them. A seal <NUM> is attached to carousel outer side <NUM> in the corner area between carousel outer side <NUM> and carousel floor <NUM>, and seals against pool outer wall <NUM> in pool gap <NUM>. As mentioned above, carousel floor <NUM>, i.e. the portions of carousel <NUM> below seal <NUM>, is liquidtight. Pool bottom <NUM> and pool outer wall <NUM> are also liquidtight, and together with carousel floor <NUM> and seal <NUM>, these elements form a closed chamber <NUM>. Closed chamber <NUM> is filled with pressurised liquid which provides a positive pressure that supports carousel <NUM> and makes carousel <NUM> movable.

A large cable carousel may have a capacity of <NUM> tonnes cable, i.e. the cable weighs <NUM><NUM> Newton. The radius of such a cable carousel may be <NUM> metres, i.e. the area of carousel floor <NUM> is πx20<NUM>=<NUM><NUM>. The contribution to the pressure in closed chamber <NUM> from the weight of the cable is thereby <NUM><NUM> N/<NUM><NUM>= <NUM> kN/m<NUM>= <NUM> x <NUM><NUM> N/m<NUM> =<NUM> bar.

<FIG> is a closer view of the lower left portion of <FIG>, seen in direction II. An extension of the concrete pool bottom <NUM> forms a foundation <NUM>. A base <NUM> made by welded steel plates is secured to the foundation <NUM> by anchor bolts <NUM>, and a centring wheel bracket <NUM> is attached to base <NUM> by bolts <NUM>. A free-running centring wheel <NUM> with a vertical rotation axis is attached to centring wheel bracket <NUM>. Centring wheel bracket <NUM> has adjustment slots <NUM> that allow horizontal adjustment relative to base <NUM>, which means that the horizontal distance between centring wheel <NUM> and carousel outer side <NUM> is adjustable. Adjusting this distance allows restricting the horizontal movement of carousel <NUM>. A horizontal stiffening plate <NUM> stiffens carousel outer side <NUM> and distributes the load from centring wheel <NUM>. <FIG> shows three centring wheels <NUM>, and there is one more for the cutaway portion of carousel <NUM>, i.e. there are a total of four centring wheels <NUM>, which allows centring carousel <NUM> in pool <NUM>.

A horizontal support beam <NUM> is supported and held in place by a combined linear bearing/hydraulic cylinder <NUM> and a hydraulic cylinder <NUM>, which in turn are attached to base <NUM> by not illustrated bolts. A linear transducer <NUM> measures the elevation of support beam <NUM> relative to base <NUM>. A hold-down wheel <NUM> is rotatably attached to support beam <NUM>, with a horizontal rotation axis parallel to the radial direction of carousel <NUM>. Hold-down wheel <NUM> touches carousel top <NUM> and restricts vertical upwards movement of carousel <NUM>. An electric motor/gearbox unit <NUM> is attached to the end of support beam <NUM>, for driving hold-down wheel <NUM>, for rotating carousel <NUM>. A vertical stiffening plate <NUM> stiffens carousel top <NUM> and distributes the load from hold-down wheel <NUM>. <FIG> shows three hold-down wheels <NUM>, and there is one more for the cutaway portion of carousel <NUM>, i.e. there are a total of four hold-down wheels <NUM>.

<FIG> further shows an extension <NUM> of carousel floor <NUM>, forming a nose beyond carousel outer side <NUM>. Seal <NUM> is clamped between nose <NUM> and a flat bar <NUM> by means of bolts <NUM>.

Pool outer wall <NUM> is formed by a vertical steel plate with an angled portion <NUM> cast in concrete bottom <NUM>. Pool outer wall <NUM> has a circular sealing surface <NUM> facing carousel outer side <NUM>. Sealing surface <NUM> is smooth to allow seal <NUM> to slide and seal against it during rotation. Sealing surface <NUM> does not need to extend over the whole of pool outer wall <NUM>, it is sufficient that sealing surface <NUM> extends over the sealing area for seal <NUM> in various operating elevations of carousel <NUM>. An overflow line <NUM> has an overflow inlet <NUM> in sealing surface <NUM>. Pool outer wall <NUM> further has a pressure sensor <NUM> in its lower portion, below seal <NUM>, to measure the pressure in closed chamber <NUM>, and a liquid sensor <NUM> in its higher portion, to initiate an alarm if the liquid level in pool gap <NUM> reaches the height of liquid sensor <NUM>.

<FIG> further shows liquid lines with an external liquid supply <NUM> with an external supply valve <NUM>, an external liquid discharge <NUM> with an external discharge valve <NUM>, a pump <NUM>, a reservoir <NUM>, a reservoir valve <NUM>, a drain valve <NUM>, a pool inlet/outlet valve <NUM>, and a pool inlet/outlet line <NUM> with a pool inlet/outlet <NUM> in pool <NUM>. Reservoir <NUM> is illustrated much smaller than it really is. Reservoir <NUM> is located below pool <NUM>, to enable gravity draining from pool <NUM> to reservoir <NUM>.

The liquid may be an oil. Preferably, however, for both environmental and economic reasons, the liquid is water, possibly with additives such as glycol or another antifreeze, corrosion inhibitor and biocide.

To start the operation of carousel <NUM> in <FIG> and <FIG>, carousel <NUM> is placed on pool bottom <NUM> when dry. Seal <NUM> seals against pool outer wall sealing surface <NUM> in pool gap <NUM>. It is thereby created a closed chamber <NUM> defined by seal <NUM>, carousel floor <NUM>, pool bottom <NUM> and pool outer wall <NUM> below seal <NUM>. Assuming the liquid is water, water is initially supplied from external liquid supply <NUM>, which typically is the municipal waterworks, through external supply valve <NUM> and reservoir valve <NUM> to reservoir <NUM>, while pump <NUM> is stopped and the other valves are closed. In reservoir <NUM>, the water is mixed with additives. The water is supplied from reservoir <NUM> to pool inlet/outlet <NUM> by running pump <NUM> while reservoir valve <NUM> and pool inlet/outlet valve <NUM> are open, while the other valves are closed. Water then enters and pressurises closed chamber <NUM>, which lifts carousel <NUM> off pool bottom <NUM>.

When carousel <NUM> has been lifted off pool bottom <NUM>, it is horizontally movable. Carousel <NUM> is centred in pool <NUM> by means of the four centre wheels <NUM>. This centring ensures that seal <NUM> seals properly.

Closed chamber <NUM> is filled until carousel top <NUM> touches hold-down wheels <NUM>. To ensure enough friction between hold-down wheels <NUM> and carousel top <NUM> to enable transfer of rotation, the downward force from hold-down wheels <NUM> is regulated by the pressure in linear bearing/hydraulic cylinder <NUM> and hydraulic cylinder <NUM>. As discussed above, a load of <NUM> tonnes of cable causes a pressure of <NUM> bar in closed chamber <NUM>. A load of perhaps a few tonnes from hold-down wheels <NUM> will therefore have little influence on the pressure in closed chamber <NUM>.

To prevent carousel outer side <NUM> from hitting pool outer wall <NUM>, and to ensure that seal <NUM> seals properly, it is required to make carousel outer side <NUM> parallel with pool outer wall <NUM>. This is achieved by levelling carousel <NUM>, i.e. making carousel top <NUM> horizontal, which is achieved by adjusting all hold-down wheels <NUM> to the same elevation.

Electric motor/gearbox unit <NUM> is then started to drive hold-down wheels <NUM> to rotate carousel <NUM>. Since carousel <NUM> is centred in pool <NUM>, and since pool <NUM> is circular about vertical axis <NUM>, carousel <NUM> now rotates about vertical axis <NUM>, as illustrated in <FIG> with reference numeral <NUM> for a rotational direction that allows winding cable <NUM> on carousel <NUM>. Carousel <NUM> is now in operation, and cable <NUM> can be wound on and unwound from carousel <NUM> by means of guide arm <NUM>, as illustrated in <FIG>.

During operation, hold-down wheels <NUM> touches carousel top <NUM>, and the elevation of carousel <NUM> can thereby indirectly be measured by linear transducer <NUM>. Carousel <NUM> may be raised during operation by raising linear bearing/hydraulic cylinder <NUM> and hydraulic cylinder <NUM>, and at the same time adding water to closed chamber <NUM>, which is carried out as during initial filling of water. Carousel <NUM> may be lowered during operation by lowering linear bearing/hydraulic cylinder <NUM> and hydraulic cylinder <NUM>, and at the same time removing water from closed chamber <NUM>, which is carried out by opening drain valve <NUM>. The force from hold-down wheels <NUM> may be regulated during operation by regulating the pressure in linear bearing/hydraulic cylinder <NUM> and hydraulic cylinder <NUM>, without changing the amount of water in closed chamber <NUM>. The pressure in pool <NUM>, i.e. closed chamber <NUM>, is measured by pressure sensor <NUM>.

Normal operating elevation of carousel <NUM> is maybe <NUM> above pool bottom <NUM>. If for some reason carousel <NUM> rises above normal operating elevation, carousel <NUM> will be lowered, as discussed above. However, if the lowering fails and carousel <NUM> rises so high that seal <NUM> is level with or above overflow inlet <NUM>, liquid will flow into overflow inlet <NUM> and further through overflow line <NUM> to reservoir <NUM>. This removes liquid below seal <NUM>, and carousel <NUM> is lowered. When carousel <NUM> has been lowered so much that seal <NUM> again is below overflow inlet <NUM>, the flow of liquid into overflow inlet <NUM> stops, and the lowering of carousel <NUM> stops.

To close down the operation, pool <NUM> can be emptied by opening drain valve <NUM>, while the other valves are closed. Reservoir <NUM> can be emptied by running pump <NUM> while reservoir valve <NUM> and external discharge valve <NUM> are open, and the other valves are closed.

The hydraulic cylinders and the electric motors for the hold-down wheels and the pump may be controlled locally or remotely from a control system. The valves may be manual or actuated and remote controlled from the same control system. The sensors may have local displays or be connected to the control system. The control system may have various degrees of automation.

Base <NUM>, centring wheel bracket <NUM>, centring wheel <NUM>, support beam <NUM>, hold-down wheel <NUM>, electric motor/gearbox unit <NUM> and associated illustrated elements together with not illustrated elements such as bolts and wiring, form a combined centring, driving, hold-down and levelling unit for cable carousel <NUM>. <FIG> shows three such units, and there is one more for the cutaway portion of carousel <NUM>. However, any number of three or more such units can be used. Further, it is not required to combine the elements carrying out these functions into one unit, they might as well be separate.

<FIG> shows another embodiment of the invention. Pool outer wall <NUM> is made of a steel sheet made from steel coil, which is cast in and backed by a foundation in the form of a concrete ring <NUM> extending around pool <NUM>. A membrane <NUM> forming pool bottom <NUM> is arranged on a foundation <NUM> of sand, and the edge of membrane <NUM> is also cast in concrete ring <NUM>, underneath pool outer wall <NUM>. A pool inlet/outlet <NUM> is formed by a penetration through membrane <NUM>. Pool <NUM> also has a drain tube <NUM> to the ground, closed by a plug <NUM>.

Concrete ring <NUM> forms a foundation for a foot <NUM>, which is anchored to concrete ring <NUM> by anchor bolts <NUM>. Foot <NUM> supports a combined centring, driving, hold-down and levelling unit which is identical to that in <FIG>, and a description of the elements included in this centring, driving, hold-down and levelling and their function as well as other items similar to <FIG> will not be repeated.

Pool outer wall <NUM> has a recess formed by an opening <NUM> through the steel sheet and an indentation in concrete ring <NUM> behind opening <NUM>. The lower edge of this recess defines an overflow inlet <NUM>, and the upper edge of the recess defines an overflow outlet <NUM>. Pool outer wall <NUM> further has a pool gap liquid outlet <NUM> leading to a pool gap outlet line <NUM>. Pool outer wall <NUM> further has a pressure sensor <NUM> in its lower portion, below seal <NUM>, to measure the pressure in closed chamber <NUM>, and a liquid sensor <NUM> in its higher portion, to initiate an alarm if the liquid level in pool gap <NUM> reaches the height of liquid sensor <NUM>.

Carousel <NUM> has a liquid reservoir <NUM> defined by carousel outer side <NUM>, a reservoir floor <NUM> and a reservoir roof <NUM>. Reservoir roof <NUM> has a vent <NUM>, and carousel top <NUM> has a vent <NUM>. Liquid reservoir <NUM> communicates with pool gap <NUM> via an opening <NUM> in carousel outer side <NUM> at the bottom of reservoir <NUM>, above seal <NUM>.

<FIG> further shows liquid lines with an external liquid supply <NUM> with an external supply valve <NUM>, an external liquid discharge <NUM> with an external discharge valve <NUM>, a pump <NUM>, a pump valve <NUM>, a pump bypass valve <NUM> and a pool inlet/outlet valve <NUM> in a pool inlet/outlet line <NUM> leading to pool inlet/outlet <NUM>.

The embodiment of the invention shown in <FIG> has no external reservoir. This means there are no place outside carousel <NUM> to store liquid when pool <NUM> and carousel reservoir <NUM> is empty or carousel <NUM> is outside pool <NUM>. The embodiment in <FIG> is therefore particularly suited when the liquid is water without additives which can be drained directly to the ground.

To start the operation of carousel <NUM> in <FIG>, carousel <NUM> is placed on pool bottom <NUM> when dry. Seal <NUM> seals against pool outer wall sealing surface <NUM> and seals pool gap <NUM>. It is thereby created a closed chamber <NUM> formed by seal <NUM>, carousel floor <NUM>, pool bottom <NUM> and pool outer wall <NUM> below seal <NUM>. Assuming the liquid is water, water is initially supplied from external liquid supply <NUM>, which is assumed to have a pressure above pool operating pressure. As an example, external liquid supply <NUM> may be the municipal waterworks, which may have a pressure of <NUM> bar. Further, for a particular design, the pool operating pressure have been estimated to <NUM> bar, taking the weight of carousel <NUM>, the weight of cable <NUM> and the forces from hold-down wheels <NUM> into consideration. Due to the pressure difference, water flows from external liquid supply <NUM> to pool inlet/outlet <NUM> by opening external supply valve <NUM> and pool inlet/outlet valve <NUM>, while pump <NUM> is stopped and the other valves are closed. Further start-up of the operation is as for the embodiment in <FIG>, and this is therefore not repeated.

As for the embodiment in <FIG>, the elevation of carousel <NUM> is measured by linear transducer <NUM>. If it is desirable to lower carousel <NUM> during operation, water can be removed from closed chamber <NUM> by opening pool inlet/outlet valve <NUM>. If it is desirable to discharge the water, external discharge valve <NUM> is also opened, while pump <NUM> is stopped and the other valves are closed. It is assumed that external liquid discharge <NUM> has atmospheric pressure, and, since the pressure in closed chamber <NUM> is above atmospheric, water will flow from closed chamber <NUM> to external liquid discharge <NUM>. Alternatively, the fluid may be stored in liquid reservoir <NUM> in carousel <NUM>. If this is desirable, pump bypass valve <NUM> is opened together with pool inlet/outlet valve <NUM>. Since pool gap <NUM> is open to the atmosphere and therefore has atmospheric pressure, and since the pressure in closed chamber <NUM> is above atmospheric, water will flow from pool closed chamber <NUM> to pool gap <NUM>. From pool gap <NUM> water will flow through reservoir opening <NUM> into carousel reservoir <NUM>. Vent <NUM> in reservoir roof <NUM> and vent <NUM> in carousel top <NUM> ensures that the water level is the same in pool gap <NUM> and carousel reservoir <NUM>.

If it is desirable to raise carousel <NUM> during operation, water can be added to closed chamber <NUM> by opening external supply valve <NUM> and pool inlet/outlet valve <NUM>, while pump <NUM> is stopped and the other valves are closed. Alternatively, fluid may be supplied from liquid reservoir <NUM> in carousel <NUM>. If this is desirable, pump <NUM> is run while pump valve <NUM> and pool inlet/outlet valve <NUM> are open, and the other vales are closed. Water is thereby pumped from pool gap <NUM> to pool closed chamber <NUM>. As the water level in pool gap <NUM> sinks, water is refilled from carousel reservoir <NUM> through reservoir opening <NUM>.

If carousel <NUM> rises above normal operating elevation and lowering as discussed above fails, and carousel <NUM> rises so high that seal <NUM> is level with or above overflow inlet <NUM>, liquid will flow from closed chamber <NUM> into overflow inlet <NUM> below seal <NUM>, through the recess formed by opening <NUM>, and through overflow outlet <NUM> into pool gap <NUM> above seal <NUM>. This removes liquid below seal <NUM>, and carousel <NUM> is lowered. When carousel <NUM> has been lowered so much that seal <NUM> again is below overflow inlet <NUM>, the flow of liquid from below seal <NUM> to above seal <NUM> stops, and the lowering of carousel <NUM> stops.

To close down the operation, carousel reservoir <NUM> can be emptied by running pump <NUM> while pump valve <NUM> and external discharge valve <NUM> are open, and the other valves are closed. Then pool <NUM> can be emptied by opening pool inlet/outlet valve <NUM> and external discharge valve <NUM>, while the other valves are closed.

<FIG> shows another embodiment of the invention. Most of <FIG> is identical to <FIG>, and only elements and functions different from <FIG> will be described.

Pool outer wall <NUM> is made by a circular steel plate with an angled portion <NUM> and braces <NUM> cast in the concrete foundation <NUM>. Seal <NUM> is by means of bolts <NUM> clamped to pool outer wall <NUM> between an upper flat bar <NUM> welded to pool outer wall <NUM> and a lower flat bar <NUM>. A pool gap drain line <NUM> extends from an inlet <NUM> in pool gap <NUM> to reservoir <NUM>.

In <FIG> carousel outer side <NUM> has a sealing surface <NUM>, and seal <NUM> slides against this surface. An overflow tube <NUM> has an inlet <NUM> and an outlet <NUM> located in carousel outer side <NUM>, with overflow inlet <NUM> below overflow outlet <NUM>. In normal operating elevation both overflow inlet <NUM> and overflow outlet <NUM> are below seal <NUM>, and overflow tube <NUM> has pool operating pressure. If carousel <NUM> for some reason rises so high above normal operating elevation that overflow outlet <NUM> is level with or above seal <NUM>, liquid will due to the higher pressure in overflow tube <NUM> flow from overflow outlet <NUM> into pool gap <NUM>. Liquid thereby flows from closed chamber <NUM> below seal <NUM> to pool gap <NUM> above seal <NUM>, and carousel <NUM> is lowered. When carousel <NUM> has been lowered so much that overflow outlet <NUM> again is below seal <NUM>, the flow of liquid from below seal <NUM> to above seal <NUM> stops, and the lowering of carousel <NUM> stops.

If the liquid level in pool gap <NUM> rises to pool gap drain line inlet <NUM>, liquid will flow by gravity from pool gap <NUM>, through pool gap drain line <NUM> to reservoir <NUM>. If the liquid level in pool gap <NUM> rises further, liquid sensor <NUM> will detect the presence of liquid and initiate an alarm.

Sealing surface <NUM> is a smooth portion of carousel outer side <NUM>, in the sealing area for seal <NUM> in various operating elevations of carousel <NUM>. Overflow outlet <NUM> is located in sealing surface <NUM>. Overflow inlet <NUM> can be located anywhere below seal <NUM> when carousel <NUM> is in the normal operating elevation. Overflow inlet <NUM> can e.g. be in carousel floor <NUM>.

<FIG> is a cutaway view of another cable carousel <NUM> according to the invention, supported by another pool <NUM> according to the invention. The outer portion of carousel <NUM> in <FIG> is identical to carousel <NUM> in <FIG>. In addition, carousel <NUM> in <FIG> has an inner side <NUM> defining a carousel central opening <NUM>, and pool <NUM> has an inner wall <NUM> defining a pool centre portion <NUM>. Carousel inner side <NUM> surrounds pool inner wall <NUM>, i.e. pool centre portion <NUM> is located in carousel central opening <NUM>. Pool centre portion <NUM> is shown as an empty space. It can, however, be anything that is not in conflict with pool <NUM> or carousel <NUM>, e.g., a foundation for a lifting crane or a platform. An inner seal <NUM> between carousel inner side <NUM> and pool inner wall <NUM> seals between them and maintains the pressure in closed chamber <NUM>.

Claim 1:
An apparatus for storing cable, comprising:
- a cable carousel (<NUM>) rotatable about a vertical axis (<NUM>);
- rotating means (<NUM>) for rotating (<NUM>) the carousel (<NUM>) about the vertical axis (<NUM>), for allowing winding cable (<NUM>) on the carousel (<NUM>) and unwinding cable (<NUM>) from the carousel (<NUM>);
- a pool (<NUM>) defined by a bottom (<NUM>) and an outer wall (<NUM>); wherein the carousel (<NUM>) is received in the pool (<NUM>);
characterized in that the apparatus further comprises:
- a seal (<NUM>) arranged in a pool gap (<NUM>) between an outer side (<NUM>) of the carousel (<NUM>) and the pool outer wall (<NUM>); portions of the carousel (<NUM>) below the seal (<NUM>) are liquidtight; the seal (<NUM>), the portions of the carousel (<NUM>) below the seal (<NUM>), the pool bottom (<NUM>), and the pool outer wall (<NUM>) thereby define a closed chamber (<NUM>); and
pressurised liquid in the closed chamber (<NUM>) provides a positive pressure for supporting the carousel (<NUM>) and allowing rotation (<NUM>) of the carousel (<NUM>); and
- hold-down means (<NUM>, <NUM>, <NUM>, <NUM>) for holding down the carousel (<NUM>), to keep the carousel (<NUM>) horizontal; wherein the hold-down means are vertically adjustable (<NUM>, <NUM>), to adjust the elevation of the carousel (<NUM>).