United States Patent [191
`Hassel
`
`US005444184A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,444,184
`Aug. 22, 1995
`
`
`
`
`
`
`
`4,707,569 11/1987 Yoshimura et a1. 4,755,629 7/1988 Beggs et a1. 4,860,343 8/1989 Zetena, Jr. 4,873,393 10/ 1989 Friesen et a1. 4,941,729 7/1990 Hardin et a1. 5,065,133 11/1991 Howard 5,070,522 12/ 1991 Nilssen 5,280,137 1/1994 Ward 463341 1/1992 European Pat. Off. .
`
`
`
`
`
`
`
`
`
`
`
`[541
`
`METHOD AND CABLE FOR
`TRANSMITTING COMMUNICATION
`SIGNALS AND ELECTRICAL POWER
`BETWEEN TWO SPACED-APART
`LOCATIONS
`[75] Inventor:
`ARild Hassel, Drammen, Norway
`[73] Assignee:
`Alcatel Kabel Norge AS, Oslo,
`Norway
`[21] App1.N0.:
`16,065
`[22] Filed:
`Feb. 10, 1993
`Foreign Application Priority Data
`[30]
`
`
`
`Feb. 12, 1992 [NO] Norway [51] Int. GL6
`
`920544
`174/113 R; 174/113 C;
`H01B 7/00
`
`[52] US. Cl. [58]
`
`
`174/121 A; 340/8549; 379/90
`174/113 R, 113 A, 113 C,
`Field of Search
`174/115, 116, 110 R, 261, 121 R, 121 A, 107,
`121 SR; 379/90, 397; 307/11, 13,
`14, 16-18, 21,
`24, 28, 37, 42; 340/850, 854.9
`References Cited
`U.S. PATENT DOCUME S
`
`[56]
`
`nm?qnn?mné,
`233333444444
`J2,s,£1,Js,s,38,./,4,
`nm?mmnuw?wmm
`
`030974060 7“
`
`AAAAAAAAAAAA
`11122167852733
`
`
`
`wammmn7nmsss 999999999999
`
`8 677
`
`DRHMMhMSBmVB
`
`n N "I"
`
`mm m me u n a
`m . m " n m a
`
`
`mm n .m o e m . .10.
`nm N m "mtu m w No
`"e m . man u n u .m
`
`
`mean wmwemn.
`nmmw. e amyc
`.luuO C C.n O
`
`n
`
`wwt/nnnnwmnww
`BwwnunsxRAmm
`/771114///-I-/ 411...?44411
`
`7.."""1777.
`
`
`
`1....- 111.
`
`
`
`511///m8 111
`
`wemwctv?mhw
`
`tMtSaab S
`
`FOREIGN PATENT DOCUMENTS
`
`0076437 4/1983 European Pat. Off. .
`
`174/120 SR
`
`e?tmgoeh a cts
`nmcemmrsn
`Wmntete I tm amanmp
`‘Le dow e .E eeftpmtm
`
`
`dmoyPo. nt
`.inofnn. n Pd tePow.m
`
`o .uakomn
`spmmoawemum G .mm
`CCCbI mic
`
`1.m nd
`0t Shum 3
`cdn?td. a ,
`
`.
`
`ho C t
`
`t n h
`
`0 0e S
`
`3220392 10/1987 Germany .
`1257325 12/1971 United Kingdom .
`2188818 4/1986 United Kingdom .
`Primary Examiner-Leo P. Picard
`Assistant Examiner—Christopher Horgan
`Attorney, Agent‘, or Firm-Ware, Fressola, Van der
`Sluys & Adolphson
`ABSTRACT
`[57]
`This invention relates to a method for transmitting com
`munication signals and electrical power on a cable be
`tween two spaced apart locations, for example between
`a land based control center and an offshore installation.
`The communication signals are transmitted over at least
`
`mwdheman m d Tmtma D nom.ecs<m
`smagoo
`
`smwnvcdmctm 8 mm .moedo tnweumimd
`
`We. OICS
`
`twmsb If.
`
`.lrs eosm
`a r ecu
`eatuwnbd % fer. Hr h
`cpmn .mo 8
`
`monhc?cc
`tc.me.msnd S Sr. He
`.mswmmbo
`
`.w 0 mm emm 0 PH SdtSH
`
`D-Link-1012
`Page 1 (of 9)
`
`

`
`US. Patent
`
`Aug. 22, 1995
`
`Sheet 1 of 3
`
`5,444,184
`
`D-Link-1012
`Page 2 (of 9)
`
`

`
`U.S. Patent
`
`Aug. 22, 1995
`
`Sheet 2 of 3
`
`5,444,184
`
`D-Link-1012
`Page 3 (of 9)
`
`

`
`US. Patent
`
`,184
`
`S3
`EL
`
`68
`
`A’!!!
`
`@zzv/
`
`D-Link-1012
`Page 4 (of 9)
`
`

`
`1
`
`5,444,184
`
`METHOD AND CABLE FOR TRANSMITTING
`COMMUNICATION SIGNALS AND ELECTRICAL
`POWER BETWEEN TWO SPACED-APART
`LOCATIONS
`
`The present invention relates to a method for trans
`mitting communication signals and electrical power on
`a cable between two spaced apart locations, in particu
`lar from a land based control center or an offshore
`installation, to a subsea installation. The invention also
`relates to cables for performing the method.
`
`10
`
`DESCRIPTION OF RELATED ART
`When new offshore oil and gas ?elds are developed,
`certain installations can be made subsea in order to
`avoid costly platform investments. It has been shown
`that well control can be performed over long distances.
`
`2
`ductors, and closed within an insulation sheath and
`outer armour, and having corrosion protection.
`In still further accord with the present invention, the
`cable comprises three paired power conductors for
`transmission of three-phase power, the three pairs being
`used for transmitting three communication channels.
`In further accord with the present invention, each of
`the conductors of the cable is multi-stranded or solid
`annealed copper.
`In still further accord with the present invention, the
`cable conductor insulation comprises thermoplastic
`polyethylene with a thickness required for transmission .
`of the rated power voltage.
`Further in accord with the present invention, the
`cable core is laid with insulating ?llers ?lled with a
`?lling compound, such as a petroleum jelly and
`wrapped with a polyester tape.
`Further still in accord with the present invention, the
`armour comprises two layers of galvanized steel wires
`laid in opposite directions.
`Experiments and studies have shown that the present
`invention provides for a method which solves the many
`questions raised. Neither the common mode signals nor
`the transformed power voltage need to be ?ltered or
`eliminated at the communication terminals. Transform
`ers and electronics are used in order to achieve the
`simplest total system.
`These and other objects, features and advantages of
`the present invention will become more apparent in
`light of the detailed description of a best mode embodi
`ment thereof, as illustrated in the accompanying draw
`mg.
`
`25
`
`30
`
`45
`
`SUMMARY OF THE INVENTION
`The present invention is to provide a method for
`operating wellhead controls from a shore based control
`center to a subsea well system with a distance up to 170
`km and more.
`In connection with a particular ?eld it seems feasible
`to arrange a manifold center approx 130 km from land.
`The different wells can be tied in to this manifold. The
`wells can be arranged in templates each having 3-5
`wells. The distance from the manifold center can be
`20-40 km.
`It is estimated that each template will require electri
`cal power in the order of 2 kW, and that a main cable
`leading from shore to the manifold should be capable of
`transferring power loads in the order of 20 kW. The
`35
`basic load will be power supply for electronics. In addi~
`tion, each template will have a local hydraulic supply
`which will be powered with electric motors. The elec
`tric motors will run only when the accumulator pres
`sure falls below a preset value. This will cause varia
`tions in the actual power demand. The communication
`signal transmission rate should be minimum 1200 baud.
`Basically we have tried to ?nd a solution comprising
`a cable which can transmit both electrical power and
`electrical signals over the required distance. Signal
`transmission over very large distances combined with
`power transmission is, however, a very challenging
`task, and raises a number of questions.
`Several systems have been studied for dealing with
`the above requirements, such as pure DC systems. An
`alternative solution is to use an AC cable with ?ber
`optic signal transmission. Still another alternative was
`to superimpose communication signals on the power
`voltage. A better solution is however provided with the
`present invention.
`According to the present invention, communication
`and electrical power are provided on a cable between
`two spaced-apart locations, wherein the communication
`signals are transmitted over at least two twisted pairs,
`the conductors of each twisted pair being connected in
`parallel to constitute a power conductor, and wherein
`the communication and power transmissions are sepa
`rated by transformers.
`In further accord with the present invention, the
`cable for transmitting the communication signals and
`electrical power between the two spaced-apart loca
`tions includes at least two power conductors, each
`being constituted by one pair of twisted insulated con
`
`55
`
`65
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 illustrates a typical ?eld layout,
`FIGS. 2 and 3 illustrate wiring diagrams, and
`FIGS. 4 and 5 illustrate crossection of two cables.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`In FIG. 1 is illustrated how a subsea ?eld installation
`1 is connected to a shore installation 2 via a cable 3. The
`installation on shore is not shown. The cable 3 leads to
`a manifold center 4 from which cables 5 and 6 lead
`respectively to templates 7 and 8 having a number of
`wells 9, 10 also.
`The cables 3, 5 and 6 shall as mentioned transmit
`electrical power as well as electrical control signals.
`The basic idea is to use three insulated twisted pairs as
`a three phase cable,—-or two insulated pairs as a none
`phase cable. Each pair is connected in parallel for the
`power transmission, and each pair is used as a signal pair
`for signal transmission.
`A wiring diagram for the three phase circuit is illus
`trated in FIG. 2, the shore side being on the left side of
`the drawing, or vice versa. Three signalling pairs 20, 21,
`22 are connected respectively to the low voltage side of
`transformers 23, 24 and 25. One of the pairs 20 may be
`used for transmitting signals to the offshore side on the
`right hand side of the drawing. A different pair 21 may
`be used for transmitting signals from a subsea installa
`tion to a shore installation, and the third pair 22 may be
`a spare pair. Alternatively, at least one of the pairs may
`be used for semi-duplex transmission of signals.
`The transformed signals pass respectively over three
`twisted cable pairs 26, 27 and 28 of a cable 29 to the high
`voltage side of a second set of transformers 30, 31 and
`
`D-Link-1012
`Page 5 (of 9)
`
`

`
`5,444,184
`3
`32, in which the signals are transformed to be connected
`to three signal pairs 33, 34 and 35 on the offshore side.
`Electrical power is transmitted from one star/delta
`connection 36 to a second star/delta connection 37 via
`three cable conductors which are constituted by the
`‘pair’-conductors 26, 27 and 28 of the cable 29. Each
`phase of the power is connected to the center of the
`high voltage winding of the transformers and do there
`fore not interfere with the signal transmission on the
`low voltage side of the transformers. No differential
`power voltage is connected to the signal pairs in the
`differential mode and the ?ltering task is therefore sev
`eral orders of magnitude easier than with conventional
`super imposed technique.
`In FIG. 3 is illustrated a similar circuit diagram for a
`one phase system. Two signal pairs 40 and 41 are con
`nected over two transformers 42 and 43 and two
`twisted cable pairs 44 and 45, two transformers 46 and
`47 at the other end of the cable 48 to two signal pairs 49
`and 50 on the other side of the transmission system. AC
`20
`power is transferred from one side 51 to the other 52 via
`the high voltage side of the transformers 42, 43 and 46,
`47 and the two ‘pair’-conductors 44 and 45.
`In FIG. 4 is schematically illustrateda crossection of
`a cable (29, FIG. 2) which is suitable for transmitting
`25
`power as well as signals over long distances. The cable
`comprises three pairs 60, 61 and 62 of twisted conduc
`tors. Each conductor is a multi strand or solid copper
`conductor 63 provided with insulation 64 to provide a
`high quality power conductor. Such a conductor is also
`a good conductor for signal transmission. This includes
`both the size of the conductor and the quality of the
`insulation.
`The lay up is somewhat conservative with respect to
`diameter increase as the pairs are laid up as circular
`elements. This will eventually give potential for a corre
`sponding diameter/weight reduction.
`The conductors shown consist of stranded, annealed
`copper wires. The insulation consists of a thermoplastic
`polyethylene. Each conductor is insulated for a certain
`operating voltage.
`The insulation material should be capable of being
`processed within tight tolerances. This is very impor
`tant for the signal/noise transmission properties. The
`material should have high dielectric strength, low di
`45
`electric constant, low tan delta, high insulation resis
`tance and the water absorption is very low.
`Polyethylene is preferred in order to be compatible
`with the existing technology for molding of joints and
`penetrators.
`The lay up is as follows: Two insulated conductors
`are twisted in a pair con?guration to improve signal
`crosstalk and the power (harmonic) related noise immu
`nity during normal operations and transient conditions.
`Each twisted pair will act as one power phase as the
`conductors are connected in parallel.
`The three twisted pairs are laid up to form a three
`core cable. The cable core is laid up with insulating
`?llers 65, 66 and 67, ?lled with a ?lling compound 68
`and wrapped with polyester tape 69. The ?lling is done
`to prevent moisture penetration and thereby obtain
`stable electrical performance. The compound may be
`petroleum jelly, not harmful to any cable components.
`A polyethylene sheath 70 is extruded over the laid up
`pairs.
`65
`The cable armour shown consists of two layers of
`round galvanized steel wires 71, 72. The outer layer of
`armour wires are laid in the opposite direction of the
`
`4
`inner layer. The counter helical wire armour is torsion
`balanced. This feature is preferable to avoid twisting of
`the cable especially during the laying operation. If the
`manifold center (4, FIG. 1) is some kind of surface
`installation, the cable must have a dynamic riser which
`requires a two layer torsion balanced armour.
`Over the armour wires 71,72 there is applied a corro
`sion protection layer 73. This layer can be servings of
`jute impregnated with asphalt, or servings of a bitumen
`impregnated polypropylene yarn which is less prone to
`microbiological degradation. Alternatively the outer
`serving can be an extruded layer of polyethene. This
`gives a better corrosion protection, but has disadvan
`tages as this prohibits a continuous earthing of the ar
`mour wires.
`In FIG. 5 is illustrated the crossection of a cable (48,
`FIG. 3) having two twisted pairs 80/81 and 82/83 mak
`ing up a star quad and the core of a cable 84 similar to
`that described in connection with FIG. 4. The outer
`layers may be as in FIG. 4. The conductors are shown
`as solid wires 85.
`When making cables as long as some 130 to 170 km it
`will normally be necessary to make factory joints. In a
`factory joint the copper conductor is usually jointed by
`means of brazing. Such conductor joint gives electrical
`resistivity equal or less than the cable conductor. It
`gives mechanical strength close to cable conductor
`itself (approx. 90%) and it gives no diameter increase.
`The dielectric in the joint is primarily a molded joint.
`Alternatively, the melting and heat shrinking tube tech
`nique can be used. When the jointing of the conductors
`is completed, the lay-up of the cable elements takes
`place. Since there are only a minor diameter increase on
`each power core, this will not cause problems in the
`further production of the cable.
`Field joints or repair joints of the conductors are
`basically equal to the factory joints, but jointing of the
`conductors and insulation will have to be done when
`the cable is in a laid up con?guration.
`Studies have shown that the above described cable
`alternative for long distance communication is a reliable
`solution.
`I claim:
`1. Apparatus for transmitting communication signals
`‘and electrical power signals between two remote loca
`tions, comprising:
`at least two twisted pairs having at least one twisted
`pair for transmitting the communication signals,
`and having conductors connected in parallel for
`transmitting electrical power signals; and
`transformer means being connected to said at least
`two twisted pairs for separating the transmission of
`the communication signals and the electrical power
`signals.
`2. Apparatus according to claim 1, wherein said appa
`ratus includes a cable having said at least two twisted
`pairs and at least two power conductors, each of said at
`least two power conductors being constituted by one
`pair of twisted insulated conductors, and said cable also
`having an insulation sheath, an outer armour and a
`corrosion protection layer for enclosing said at least
`two twisted pairs.
`3. Apparatus according to claim 2, wherein the cable
`further comprises three paired power conductors for
`transmission of three phase power, the three paired
`power conductors being used for transmitting three
`communication channels.
`
`60
`
`35
`
`40
`
`D-Link-1012
`Page 6 (of 9)
`
`

`
`5,444,184
`5
`4. Apparatus according to claim 2, wherein each of
`said at least two power conductors comprises a multi
`strand or solid annealed copper wires.
`5. Apparatus according to claim 4, wherein the cables
`further includes conductor insulation surrounding said
`multi strand or solid annealed wires which is made of
`thermoplastic polyethylene with a thickness required
`for transmission of the rated power voltage.
`6. Apparatus according to claim 2, wherein the cable
`has a core with insulating ?llers, is ?lled with a ?lling
`compound such as a petroleum jelly and wrapped with
`a polyester tape;
`7. Apparatus according to claim 2, wherein the outer
`armour comprises two layers of galvanized steel wires
`wound in opposite directions.
`8. Apparatus according to claim 1, wherein said appa
`ratus is arranged in a three phase circuit for connection
`to a star/delta power connection, comprising:
`three twisted pairs;
`three pairs of transformers, each having a high volt~
`age side; and
`each of said three twisted pairs being connected be
`tween respective high voltage sides of a corre
`sponding one of said three pairs of transformers.
`
`5
`
`25
`
`6
`9. Apparatus according to claim 8, wherein each
`transformer of said three pairs of transformers has a
`respective center of the high voltage side for connect
`ing to a separate phase conductor of the star/delta
`power connection.
`10. Apparatus according to claim 8, wherein said
`apparatus is arranged in a one phase circuit for connec
`tion to AC power connections, comprising:
`two twisted pairs;
`two pairs of transformers, each having a high voltage
`side; and
`each of said two twisted pairs being connected be
`tween respective high voltage sides of a corre—
`sponding one of said two pairs of transformers.
`11. Apparatus according to claim 10, wherein each
`transformer of said two pairs of transformers has a re
`spective center of the high voltage side for connecting
`to a separate phase conductor of the AC power connec
`tions.
`12. Cable for transmitting electric power and commu
`nication signals, characterized in that the cable has a
`core comprising at least two power conductors, each
`having two twisted, insulated conductors and being
`surrounded by an insulation sheath, armour and corro
`sion protection.
`
`35
`
`45
`
`50
`
`55
`
`65
`
`* *
`
`* * *
`
`D-Link-1012
`Page 7 (of 9)
`
`

`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENT NO. :
`DATED
`:
`
`5 , 444 , 184
`August 22, 1995
`
`INVENTOWS) I
`
`Arild Hassel
`
`It is certified that error appears in the above-indentified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`On the title page, item [75]
`
`delete "ARild Hassel" and insert --Arild Hassel——.
`
`Signed and Sealed this
`
`Twelfth Day of December, 1995
`
`Emu,“
`
`BRUCE LEHMAN
`
`Commissioner of Parents and Trademarks
`
`D-Link-1012
`Page 8 (of 9)
`
`

`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENTNO._:
`DATED
`:
`INVENTOWS) 1
`
`5,444,184
`August 22, 1995
`Arild Hassel
`
`it is certified that error appears in the above-indentified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`On the title page, item [75]
`
`delete "ARild Hassel" and insert --Arild Hassel——.
`
`Signed and Sealed this
`
`Twelfth Day of December, 1995
`6014“ W
`
`BRUCE LEHMAN
`
`Commissioner of Parents and Trademarks
`
`Am‘
`
`Arresting O?icer
`
`D-Link-1012
`Page 9 (of 9)