Page 1 of 12 STANDARD SPECIFICATION FOR INSTRUMENT CABLES DOCUMENT NO : 44-LK-5100-00/J.02/0014-A4 Rev No. Issue Date Pages Rev Description Prepared A 12-08-08 12 Issued for Comments / Approval By Checked By Approved By RCK GDR BSP
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 2 of 12 TABLE OF CONTENTS 1.0 PURPOSE 2.0 SCOPE 3.0 TECHNICAL REQUIREMENTS 3.1 INSTRUMENT CABLES 3.2 DESIGN AND TESTING STANDARDS 3.3 CABLE CONSTRUCTION 3.4 CABLE DRUMS 3.5 IDENTIFICATION MARKS ON CABLES 3.6 CABLE GLANDS 3.7 JUNCTION BOXES 3.8 MULTI CABLE TRANSIT 4.0 RELATED DOCUMENTATION 5.0 ATTACHMENTS
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 3 of 12 1.0 PURPOSE 2.0 SCOPE The purpose of this specification is to define the minimum requirements of design and manufacture of instrument cables and related accessories. The scope of work shall include design, manufacture, testing and supply of instrument cables and related accessories. The inspection requirements shall be as per the inspection plan. 3.0 TECHNICAL REQUIREMENTS 3.1 INSTRUMENT CABLES This specification covers the requirements for instrument signal cables, thermocouple extension cables, RTD cables and power / control cables. 3.1.1 Single pair shielded signal / alarm cables shall be used between field instruments / switches and junction boxes / local control panels. 3.1.2 Single pair shielded thermocouple extension cables shall be used between thermocouple head and junction boxes / transmitters / local control panel mounted instruments. 3.1.3 Single triad shielded signal cables shall be used between RTD head and junction boxes / transmitters / local control panel mounted instruments. 3.1.4 For fieldbus compatible instrument single pair shielded cable shall be used between instrument to junction box/ local panel and to control room. Foundation Field bus shall be Type-A cable. Construction of same shall be as Per IEC 61158-2. Trunk cable shall be used of 1 Pair, 5 Pair, 12 Pair. 3.1.5 Separate Multipair/ multitriad cables shall be used between junction boxes/ local control panel and control room as per following applications. 4-20 ma signals (for conventional HART Transmitters) Foundation Field signals Thermocouple signals Resistance Temperature Detectors (RTD) signals Switch contacts / Proximity switch contacts Gas detectors 3.1.6 Power cables shall be used between power supply distribution boards and power consumers such as control panels, DCS / PLC cabinets, any instruments requiring power supply, etc. 3.1.7 Control cables shall be used for solenoid valves. 3.1.8 For solenoid valve signals and power supply to instruments, junction boxes shall be used.
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 4 of 12 3.1.9 The cable design shall generally follow BS 5308 Part-1 for various cables listed in clause 3.1.5 above. Thermocouple cables design shall comply with ANSI MC 96.1. The power and control cables shall be generally as per BS 6346. For these cables, equivalent IEC/IS specifications are also acceptable. 3.1.10 The insulation grade shall be 1100 V for all cables. 3.1.11 The primary insulation shall be cross-linked Polyethylene with temperature rating 70 deg.c conforming to BS- 5308 / IS 7098. Inner and outer sheath / jacket shall be made of extruded fire retardant, low smoke,low halogen, low toxic, polymeric compound having physical properties as per IS-5831 Type ST2. 3.1.12 All cables shall be armoured and suitable for operation when installed as follows: - Directly buried in the ground - Fastened to cable ladder rack or tray in the open air - In underground ducts - In overhead closed cable ducts 3.1.13 Running length of the cable shall be printed at least at every 5 metre interval. For multipair/ multitriad cables, pair identification shall be provided with numbers at interval of not more than 250 mm as per vendor s standard. 3.1.14 Contractor shall ensure a minimum of 20% of quantity of each type of cables supplied as spare including any special cable and in each multipair cables 20% pairs shall be kept as spare. 3.1.15 A pair of communication wire shall be provided for multipair / multritraid cables. Each wires shall be 0.5 mm 2 of plain annealed single or multi-strand copper conductor with 0.4 mm thick 70 Deg.C XLPE insulation. 3.1.16 All cables shall be fire retardant and low smoke. 3.2 DESIGN AND TESTING STANDARDS 3.2.1 Instrument signal, RTD and thermocouple cables Conductors Insulation: XLPE Armour: Inner & Outer Sheath-PVC: STANDARDS BS 6360/ IS 8130 for instrument signal and RTD cables and ANSI MC 96.1/IEC-60584-3 for thermocouple cables. Insulation shall be Cross-linked Polyethylene (XLPE) as per BS 5308 / IS 7098. Round wire armour galvanized steel as per IS 1554 Part 1 Extruded Fire Retardant, Low Smoke, Low Halogen, Low Toxic, PVC having physical properties as per IS 5831-Type ST2. Flammability and chemical properties shall be as follows: Oxygen Index: 30 (minimum) at room Temp as per ASTM-D-2863-77 Temperature Index: 250 Deg C (minimum) at Oxygen Index of 21 as per ASTM-D-2863. Light Transmission: 70% (minimum) as per IEC 1034. Flammability test: As per IEC 332 Part-1 & Part-3
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 5 of 12 Cat. A Corrosivity of combustion gases: ph-index> 4.3, Electrolytic conductivity < 100 micro S/cm as per IEC 754-2 Toxicity index: Maximum 05 Gases to be extracted HCL, HBr, HF, CO, CO2, NO, SO2, HCN as per NES-713. HCL shall be first gas to be extracted Inner Sheath and outer sheath thickness: Min. Inner sheath thickness and outer sheath thickness shall be as per IS:1554(P-1)1988 (should not be less than 0.5 mm). Outer Sheath Colour: Blue Inner Sheath Colour: Black Testing of the instrument BS 5308 signal and RTD cables. Testing / Calibration of ANSI MC96.1 / IEC-60584-2 thermocouple cables. Dimensions: BS 5308 3.2.2 Power and control cables STANDARDS Conductors IS : 8130 / BS 6360 Insulation-XLPE Insulation shall be Cross-linked Polyethylene (XLPE) as per BS 5308 / IS 7098. Armour Round wire armour galvanized steel as per IS 1554 Part 1 Inner & Outer Sheath-PVC Extruded Fire Retardant, Low Smoke, Low Halogen, Low Toxic, PVC having physical properties as per IS 5831- Type ST2. Flammability and chemical properties shall be as follows: Oxygen Index: 30 (minimum) at room Temp as per ASTM-D-2863-77 Temperature Index: 250 Deg C (minimum) at Oxygen Index of 21 as per ASTM-D-2863. Light Transmission: 70% (minimum) as per IEC 1034. Flammability test: As per IEC 332 Part-1 & Part-3 Cat. A Corrosivity of combustion gases: ph-index> 4.3, Electrolytic conductivity < 100 micro S/cm as per IEC 754-2 Toxicity index: Maximum 05 Gases to be extracted HCL, HBr, HF, CO, CO2, NO, SO2, HCN as per NES-713. HCL shall be first gas to be extracted. Testing and Dimensions of the cables Inner Sheath and outer sheath thickness: Min. Inner sheath thickness and outer sheath thickness shall be as per IS:1554(P-1)1988, should not be less than 0.5 mm. Power Cables: Black Control Cables: Blue with black bands (4 bands at 90 o apart) IS : 1554 Part I, BS 6469 / BS 6346
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 6 of 12 3.3 CABLE CONSTRUCTION The various mechanical / electrical parameters indicated here are indicative and the contractor shall be responsible to select / design the cables as per applicable standards. 3.3.1 Instrument signal cables (4 20 ma or switch contacts): ITEMS Conductor i) Single Pair ii) 6/ 12 Pair 7 stranded / 0.53 mm dia (1.5 mm 2 ) stranded annealed tinned copper conductors of electrolytic grade copper. 7 stranded / 0.53 mm dia (1.5 mm 2 ) annealed tinned copper conductors of electrolytic grade copper. 3.3.2 RTD cables: Insulation Cross-linked Polyethylene (XLPE) as per BS 5308/IS 7098. Inner & outer PVC, fire retardant, low smoke, low halogen, low toxic, polymeric sheath compound. Pairs Two insulated conductors shall be uniformly twisted together to form a pair at least 10 twists per metre. Maximum DC Shall not exceed 12.3 ohms/ km at 20ºC for cables with 1.5 mm 2 resistance conductor. Mutual BS 5308 Part 1 capacitance L/R ratio of BS 5308 Part 1 adjacent cores /pairs Shield Shield shall be aluminium backed mylar / polyester tape bonded together with the metallic side down helically applied with either side having 25% overlap and 100% coverage. The minimum shield thickness shall be 0.05 mm in case of single pair and 0.075 mm in case of multipair cable. Drain wire Drain wire shall be provided for individual pair and overall shield with 0.5 mm 2 multistranded bare tinned annealed copper conductor continuously in contact with aluminium side of shield. The drain wire resistance including shield shall not exceed 30 ohm/km. Electrostatic noise rejection ratio shall be over 76 db. Colour coding Individual pair core insulation : Blue & Black Inner jacket : Black Outer jacket : Blue for intrinsically safe application and blue with black bands (4 bands at 90 o apart) for non IS applications. ITEMS Conductor 1 Triad 7 stranded / 0.53 mm dia (1.5 mm 2 ) annealed tinned copper conductors of electrolytic grade copper. 6/ 8 Triad 7 stranded / 0.53 mm dia (1.5 mm 2 ) annealed tinned copper conductors of electrolytic grade copper. Insulation Cross-linked Polyethylene (XLPE) as per BS 5308 / IS 7098 Inner & outer sheath PVC, fire retardant, low smoke, low halogen, low toxic, polymeric compound.
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 7 of 12 Triads Maximum DC resistance Mutual capacitance L/R ratio of adjacent triads Shield Drain wire Colour coding Three insulated conductors shall be uniformly twisted together to form a Triad at least 10 twists per metre. Shall not exceed 12.3 ohms/ km at 20ºC for cables with 1.5 mm 2 conductor. BS 5308 Part 1 BS 5308 Part 1 Shield shall be aluminium backed mylar / polyester tape bonded together with the metallic side down helically applied with either side having 25% overlap and 100% coverage. The minimum shield thickness shall be 0.05 mm in case of single triad and 0.075 mm in case of multitriad cable Drain wire shall be provided for individual pair and overall shield with 0.5 mm 2 multistranded bare tinned annealed copper conductor continuously in contact with aluminium side of shield. The drain wire resistance including shield shall not exceed 30 ohm/km. Electrostatic noise rejection ratio shall be over 76 db. Core insulation : Red, Yellow and Blue Inner jacket : Black Outer jacket : Blue for intrinsically safe application and blue with black bands (4 bands at 90 apart). 3.3.3 Thermocouple cables: ITEMS Conductor i) Single pair cable 16 AWG or 1.5 mm 2 solid conductors Conductor material should be as follows: K type T/C Nickel / Chromium; Nickel / Aluminium (KX), Class 1. Insulation Cross-linked Polyethylene (XLPE) as per BS 5308 / IS 7098 Colour code: Nickel / Chromium: Green Nickel / Aluminium: White Pairs Two insulated conductors shall be uniformly twisted together to form a pair at least 10 twists per metre. The lay length of adjacent pairs / Triads in case of Multipair cables shall not be equal, to reduce cross-talk. Mutual capacitance BS 5308 Part 1 L/R ratio of BS 5308 Part 1 adjacent pairs Core inductance Shall not exceed 4 mh/km. However, for J-type thermocouple inductance could be 8 mh/km. Shield Shield shall be aluminium backed mylar / polyester tape bonded together with the metallic side down helically applied with either side having 25% overlap and 100% coverage. The minimum shield thickness shall be 0.05 mm in case of single pair and 0.075 mm in case of multi pair cable Drain wire Drain wire shall be provided for individual pair and overall shield with 0.5 mm 2 multistranded bare tinned annealed copper
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 8 of 12 Colour coding conductor continuously in contact with aluminium side of shield. The drain wire resistance including shield shall not exceed 30 ohm/km. Electrostatic noise rejection ratio shall be over 76 db. Outer sheath colour - Green Inner sheath colour - Black Note: All thermocouple extension cable shall be matched and calibrated in accordance with IEC-60584-2 / ANSI MC 96.1 3.3.3 Control cables. ITEMS Conductor 2 Core / Multi-core type 7 stranded / 0.53 mm dia (1.5 mm 2 ) annealed tinned copper conductors of electrolytic grade copper. 3.3.4 Power cables. Insulation Cross-linked Polyethylene (XLPE) as per BS 5308 / IS 7098 Inner & outer sheath PVC, fire retardant, low smoke, low halogen, low toxic, polymeric compound. Maximum DC resistance Shall not exceed 12.3 ohms/ km at 20ºC for cables with 1.5 mm 2 conductor Core Identification IS : 1554 / BS 6746 ITEMS Conductor 7 stranded / 0.67 mm dia. (2.5 mm 2 ) annealed tinned copper conductors of electrolytic grade copper. The size of the conductor specified here is minimum. However, the exact size of the conductor shall be selected based on the length of cable and power consumption. For higher conductor sizes, aluminium can be considered. Insulation Cross-linked Polyethylene (XLPE) as per BS 5308 / IS 7098 Core Identification IS-1554 / BS 6746 Colour coding Outer sheath colour Black Neutral wire insulation colour Black Phase wire insulation colour Red Ground wire insulation colour - Green 3.3.5 Special Cables 3.3.5.1 Ethernet cables EIA/TIA 568 A Category 5, 4 pair 0.5 mm2 (24 AWG) solid conductors, with plastic foil wrapping. Overall screen to consist of aluminium bonded polyester tape and tinned copper wire. Overall sheath shall be light grey PVC. 3.3.5.2 Fibre optic cable 62.5 / 125 micron multimode, graded index, glass silica fibre core, mechanical protection provided by round galvanized steel armour with polyester laminated tape layered over inner sheath. Outer sheath shall be orange.hdpe conduit shall be orange colour. 3.3.5.3 Foundation Fieldbus(FF) cables colour code:
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 9 of 12 FF Trunk cables shall be Orange with 4 Black longitudinal stripes at 90 deg apart. FF Spur cables (IS) shall be Orange with 4 Blue longitudinal stripes at 90 deg apart. 3.3.6 Any other special cables such as co-axial cable or cables with glass insulation, required for instruments shall also be supplied as per requirements. Vendor shall ensure that these cables are armoured type and shall meet all other requirements specified in clause 3.3.1 through 3.3.5, as applicable. 3.3.7 Cable Testing:- Vendor shall submit routine and Acceptance test certificates, in original at the time of delivery of cables. 3.3.7.1 Type Test:- Certificate from independent test house for the following tests shall be furnished by the vendor for the FRLS low halogen sheathed cable. a) Flammability Test as per IEC 60332, Part-III, Cat A. b) Electrostatic noise Rejection test. c) Oxygen Index, Temperature rating, light transmission, ph Index, electrical conductivity and toxicity index for the cable 3.3.7.2 Routine Test and Acceptance test :- Each of the following tests to be carried out by vendor during various stages of manufacturing. Purchaser shall review the related documentations. In addition, the following test shall be carried out for checking properties of low halogen FRLS sheathing material. a) Light Emission test as per IEC-1034. Acceptance norms shall be minimum 70% b) Determination of the degree of acidity of gases evolved during combustion as per IEC 754-2 (ph value to be minimum 4.3 and conductivity to be maximum 100 micro Siemens/cms c) Toxicity Index as per NES-713. Value shall not exceed 5 d) Tear Resistance as per BS 7655 Section 6.1 e) Abrasion test method as per BS 6724 Annexure E These tests shall be carried in presence of purchaser or his authorized representatives. Immediately after completion of the electrical test the ends of the cable shall be sealed to prevent ingress of moisture with suitable of rubber/pvc caps. 3.4 CABLE DRUMS 3.4.1 Cables shall be drummed in continuous lengths on cable drums. For protection during transport and storage, battens shall be fitted around the entire periphery of the drum. 3.4.2 Drum identification shall be painted black on both sides of drum with permanent oil paint. The following information shall be given on the drums as a minimum: - Drum identification number - Voltage grade - Type of cable. - Number of cores and cross-sectional area - Cable quantity - Purchaser's order number and item number
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 10 of 12 - Total weight of cable and drum 3.5 IDENTIFICATION MARKS ON CABLES: 3.5.1 Signal Cables: Outer Embossing: Following embossing should be in bold fonts at outer sheath at every 5 meter interval. Type of Cable i.e. Signal Cable No of Pairs i.e. 1, 6, 12 etc. Core Size i.e. 1.5 sq mm etc. Sequential meter marking shall be embossed at every 1 meter interval Individual pairs Embossing and identification: Core no shall be printed on each core for identification at regular interval of 250 mm or so. The pair numbers shall be available on individual pair by method of polyester number tape also. 3.5.2 Control Cables: Following embossing should be in bold fonts at outer sheath at every 5 meter interval. Type of Cable i.e. Control Cable No of Cores i.e. 2, 4, 10, 12, 24 etc. Core Size i.e. 1.5 sq mm Sequential meter marking shall be embossed at every 1 meter interval 3.5.3 Thermocouple Cables: Outer Embossing: Following embossing should be in bold fonts at outer sheath at every 5 meter interval. Type of Cable i.e. T/C Cable No of Pairs Core Size i.e. 16 AWG Temperature Range Sequential meter marking shall be embossed at every 1 meter interval Individual pairs Embossing and identification: Each core of pair shall be numbered for identification at regular interval of 250 mm or so. 3.6 CABLE GLANDS 3.6.1 Cable glands required for glanding all cables at both ends shall be supplied by contractor. 3.6.2 A minimum of 20% of cable glands shall be supplied as spare. 3.6.3 Cable glands shall be of SS 316 and double compression type suitable for armoured cables. 3.6.4 All cable glands shall be weatherproof to IP-66. Flameproof glands wherever required shall be supplied with Ex(d) certification suitable for Gas Groups IIA / IIB / IIC. All cable glands shall be with LSF shrouds. 3.6.5 For all field items and junction box end, NPT threaded cable glands shall be used and for control room / control panel end, cable glands shall be ET threaded types.
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 11 of 12 3.7 JUNCTION BOXES 3.7.1 Junction boxes shall be of die-cast aluminium alloy (LM-6) epoxy painted body. All junction boxes shall be weatherproof to IP 66 as a minimum. Flame proof junction boxes wherever required shall be supplied with Ex (d) certification. All flame proof JB s shall be provided with labels for isolating power supply before opening cover. All JB s for intrinsic safe signals shall be identified on name plate accordingly. 3.7.2 Junction box shall have screwed covers. 3.7.3 Junction box sizes shall be standardized to two types accommodate 44 terminals and 88 terminals. This includes separate terminals for shields and 20% spare terminals. All terminals shall be suitable for 4mm 2 conductors. 3.7.4 Each JB shall be provided with 2 multi-cable entries with one plugged with weather proof, explosion proof plugs as required. 3.7.5 Plugs shall be Ex (d) certified for flameproof junction boxes. 3.7.6 Telephone sockets and plugs shall be provided in all junction boxes. 3.7.7 In general separate junction boxes shall be used for the following: - Thermocouples / RTDs / SMART Transmitter / Positioner - Non SMART Transmitters (Analog Transmitters for Anti-surge control etc.) - Switches / Push Buttons - Solenoid valves - Power - Alarm - Shutdown - Gas detector ( Separate JB s for intrinsic safe, non-intrinsic safe circuits ) In general all alarm signals shall be taken to DCS and all shutdown signals to PLC. Accordingly separate junction boxes shall be provided to Alarm and Shutdown signals. 3-way junction boxes shall be used for connecting the field transmitter, field mounted analog I.S. indicator in series with control room receiver. 3.8 MULTI CABLE TRANSIT 3.8.1 The cable entry into the Satellite Rack Room/control room, analyser rooms/ shelters shall be through Multi Cable Transit Blocks (MCT). The MCT s shall be sized, supplied and installed at site by contractor. The required cutout sizes and frames sizes shall be calculated and shall be co-ordinated with control room contractor. 3.8.2 The MCT frames shall be of Standard RGB type of Brattberg or Roxtex and of steel construction. The maximum height of frame shall not exceed 600 mm unless otherwise specified. The MCT frames provided should be suitable to withstand blast intensity for which blast proof control room has been designed. The MCT shall be supplied complete with insert blocks, spare blocks, stay plates, end-packing etc. 3.8.3 Contractor shall size and provide MCT considering 50% spares for each cable size/cable OD. Contractor shall also provide 50% spare insert blocks in each cable size / O.D. as loose supply. Intrinsically safe cables, low power cables, non-intrinsically safe cables and power cables for instruments (110 V AC or above) shall be suitably separated from each other cables within the MCT frame and shall be routed through separate MCT blocks.
STANDARD SPECIFICATION FOR INSTRUMENT CABLES Page 12 of 12 3.8.4 Separate MCT frame shall be considered for electrical cables. The MCT shall be installed as per the recommended practice of supplier. No spare space shall be left uncovered in the frame and shall be filled with dummy block of suitable size. 4.0 RELATED DOCUMENTATION Nil 5.0 ATTACHMENTS Nil