GB2154784A - Improvements relating to electric cables - Google Patents

Improvements relating to electric cables Download PDF

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Publication number
GB2154784A
GB2154784A GB08504381A GB8504381A GB2154784A GB 2154784 A GB2154784 A GB 2154784A GB 08504381 A GB08504381 A GB 08504381A GB 8504381 A GB8504381 A GB 8504381A GB 2154784 A GB2154784 A GB 2154784A
Authority
GB
United Kingdom
Prior art keywords
mineral
cable
insulated
powdered
coloured
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08504381A
Other versions
GB8504381D0 (en
Inventor
Jeffrey Winstanley
John Thomas Roberts
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Balfour Beatty PLC
Original Assignee
BICC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BICC PLC filed Critical BICC PLC
Publication of GB8504381D0 publication Critical patent/GB8504381D0/en
Publication of GB2154784A publication Critical patent/GB2154784A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/16—Rigid-tube cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/36—Insulated conductors or cables characterised by their form with distinguishing or length marks
    • H01B7/361—Insulated conductors or cables characterised by their form with distinguishing or length marks being the colour of the insulation or conductor

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  • Insulated Conductors (AREA)

Abstract

A mineral-insulated cable comprises at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation which has been coloured to provide a means of identifying the particular type or range of mineral-insulated cable and/or the type of mineral insulation and/or the manufacturer of the cable.

Description

SPECIFICATION Improvements relating to electric cables This invention relates to electric cables of the kind comprising at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation. Such cables are generally known as, and shall be referred hereinafter to as, "mineral-insulated cables".
The object of this invention is to provide a mineral-insulated cable which can be easily identified from other mineral-insulated cables at the end of a length of finished cable.
In accordance with the present invention a mineral-insulated cable comprises at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation which has been coloured to provide a means of identifying the particular type or range of mineral-insulated cable and/or the type of mineral insulation and/or the manufacturer of the cable.
Preferably, the powered mineral insulation is coloured by blending with substantially white mineral insulating powder an electrically suitable powdered pigment or pigments, but, in some circumstances, any other method of colouring the powdered mineral insulation may be employed e.g. coating the white mineral powder with a coloured pigment or pigments.
Preferably, also, the or each visually coloured pigment does not undergo any appreciable colour change at temperatures below 500"C and remains electrically stable at these temperatures. Suitable pigments may, for example, be chosen from cadmium pigments, lead pigments, chromium pigments, cobalt pigments and ultramarines.
Preferably only one coloured powdered mineral insulation is used per cable.
Where two or more conductors are to be insulated from one another and the enclosing metal sheath, two or more powdered mineral insulations of two or more colours differing from one another may be used to form around each conductor a definite region differing in colour from the region around the or each other conductor, thus providing not only means for identification of the type of mineralinsulated cable but also to identify specific conductors within that cable.
Preferably the coloured powdered mineral insulation contains no more than 2% by weight pigment.
By using specifically coloured pigments in specific cable types, a complete range of mineral-insulated cables containing, for example, siloxanes as impregnants can be identified from each other and from those mineral-insulated cables containing no impregnants without the need of special tools or of specially trained personnel. The coloured powdered mineral insulation is consistent throughout the entire length of the final cable, and thus, by cutting the cable at any point along its length, the cable can be easily identified by the colour or colours of the powdered mineral insulation.
Example 1 A mineral-insulated cable containing, as an insulant, powdered magnesium oxide impregnated with mono-methylpolysiloxane and, to identify this mineral-insulated cable from other mineral-insulated cables containing no siloxane impregnant, 2% by weight of a blue coloured pigment being a reaction product of high temperature calcination of cobalt and aluminium oxides.
Example 2 A mineral-insulated cable designed for use at low voltages containing, as an insulant, powdered magnesium oxide and to identify this mineral-insulated cable from other mineral-insulated cables of higher voltage rating, 2% by weight of a red coloured pigment of calcined cadmium sulphoselenide containing inert barium sulphate as an extender.
1. A mineral-insulated cable comprising at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation which has been coloured to provide a means of identifying the particular type or range of mineralinsulated cable and/or the type of mineral insulation and/or the manufacturer of the cable.
2. A mineral-insulated cable as claimed in Claim 1, wherein the powdered mineral insulation is coloured by blending with substantially white mineral insulating powder an electrically suitable powdered pigment or pigments.
3. A mineral-insulated cable as claimed in Claim 2, wherein the or each pigment does not undergo any appreciable colour change at temperatures below 500C and remain electri cally suitable at those temperatures.
4. A mineral-insulated cable as claimed in Claim 2 or Claim 3, wherein the or each pigment is any one of cadmium pigments, lead pigments, chromium pigments, cobalt pigments and ultramarines.
5. A mineral-insulated cable comprising two or more conductors insulated from each other and from the enclosing metal sheath by at least two tightly compacted powdered mineral insulations of two or more colours differ
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to electric cables This invention relates to electric cables of the kind comprising at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation. Such cables are generally known as, and shall be referred hereinafter to as, "mineral-insulated cables". The object of this invention is to provide a mineral-insulated cable which can be easily identified from other mineral-insulated cables at the end of a length of finished cable. In accordance with the present invention a mineral-insulated cable comprises at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation which has been coloured to provide a means of identifying the particular type or range of mineral-insulated cable and/or the type of mineral insulation and/or the manufacturer of the cable. Preferably, the powered mineral insulation is coloured by blending with substantially white mineral insulating powder an electrically suitable powdered pigment or pigments, but, in some circumstances, any other method of colouring the powdered mineral insulation may be employed e.g. coating the white mineral powder with a coloured pigment or pigments. Preferably, also, the or each visually coloured pigment does not undergo any appreciable colour change at temperatures below 500"C and remains electrically stable at these temperatures. Suitable pigments may, for example, be chosen from cadmium pigments, lead pigments, chromium pigments, cobalt pigments and ultramarines. Preferably only one coloured powdered mineral insulation is used per cable. Where two or more conductors are to be insulated from one another and the enclosing metal sheath, two or more powdered mineral insulations of two or more colours differing from one another may be used to form around each conductor a definite region differing in colour from the region around the or each other conductor, thus providing not only means for identification of the type of mineralinsulated cable but also to identify specific conductors within that cable. Preferably the coloured powdered mineral insulation contains no more than 2% by weight pigment. By using specifically coloured pigments in specific cable types, a complete range of mineral-insulated cables containing, for example, siloxanes as impregnants can be identified from each other and from those mineral-insulated cables containing no impregnants without the need of special tools or of specially trained personnel. The coloured powdered mineral insulation is consistent throughout the entire length of the final cable, and thus, by cutting the cable at any point along its length, the cable can be easily identified by the colour or colours of the powdered mineral insulation. Example 1 A mineral-insulated cable containing, as an insulant, powdered magnesium oxide impregnated with mono-methylpolysiloxane and, to identify this mineral-insulated cable from other mineral-insulated cables containing no siloxane impregnant, 2% by weight of a blue coloured pigment being a reaction product of high temperature calcination of cobalt and aluminium oxides. Example 2 A mineral-insulated cable designed for use at low voltages containing, as an insulant, powdered magnesium oxide and to identify this mineral-insulated cable from other mineral-insulated cables of higher voltage rating, 2% by weight of a red coloured pigment of calcined cadmium sulphoselenide containing inert barium sulphate as an extender. CLAIMS
1. A mineral-insulated cable comprising at least one conductor insulated from an enclosing metal sheath, or where there are two or more conductors from each other and from the enclosing metal sheath, by a tightly compacted powdered mineral insulation which has been coloured to provide a means of identifying the particular type or range of mineralinsulated cable and/or the type of mineral insulation and/or the manufacturer of the cable.
2. A mineral-insulated cable as claimed in Claim 1, wherein the powdered mineral insulation is coloured by blending with substantially white mineral insulating powder an electrically suitable powdered pigment or pigments.
3. A mineral-insulated cable as claimed in Claim 2, wherein the or each pigment does not undergo any appreciable colour change at temperatures below 500C and remain electri cally suitable at those temperatures.
4. A mineral-insulated cable as claimed in Claim 2 or Claim 3, wherein the or each pigment is any one of cadmium pigments, lead pigments, chromium pigments, cobalt pigments and ultramarines.
5. A mineral-insulated cable comprising two or more conductors insulated from each other and from the enclosing metal sheath by at least two tightly compacted powdered mineral insulations of two or more colours differ ing from one another, to form around each conductor a definite region differing in colour from the region around the or each other conductor.
6. A mineral-insulated cable as claimed in any of the preceding Claims, wherein the coloured powdered mineral insulation contains no more than 2% by weight pigment.
7. A mineral-insulated cable substantially as hereinbefore described in Example 1 or Example 2.
GB08504381A 1984-02-20 1985-02-20 Improvements relating to electric cables Withdrawn GB2154784A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB848404408A GB8404408D0 (en) 1984-02-20 1984-02-20 Electric cables

Publications (2)

Publication Number Publication Date
GB8504381D0 GB8504381D0 (en) 1985-03-20
GB2154784A true GB2154784A (en) 1985-09-11

Family

ID=10556884

Family Applications (2)

Application Number Title Priority Date Filing Date
GB848404408A Pending GB8404408D0 (en) 1984-02-20 1984-02-20 Electric cables
GB08504381A Withdrawn GB2154784A (en) 1984-02-20 1985-02-20 Improvements relating to electric cables

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB848404408A Pending GB8404408D0 (en) 1984-02-20 1984-02-20 Electric cables

Country Status (1)

Country Link
GB (2) GB8404408D0 (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB629923A (en) * 1947-12-04 1949-09-30 Ralph Poole Improvements in or relating to electric cables

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB629923A (en) * 1947-12-04 1949-09-30 Ralph Poole Improvements in or relating to electric cables

Also Published As

Publication number Publication date
GB8504381D0 (en) 1985-03-20
GB8404408D0 (en) 1984-03-28

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Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)