Screend Cable/Instrumentation Cables
 


SHIELDED / BRAIDED WIRES & CABLES

 

Cables used for process industry have to be shielded to avoid electrical interface disturbances, shielding is a metallic cover over the conductor or the cable itself with the facility to ground the metal, copper & aluminum are used for this purpose, based on the type of cable, it's insulation, bending radius required and mechanical protections required.

' Prestige' offers the complete range of shields designed specially as required by different type of cables along with customer requirements and specifications.


I. BRAIDED:

Multiple copper wires are braided over the conductor / single pair / 1 triad with a minimum coverage of 70% to 90% max., this braid can also used as an overall shield on multicore / multipair / multi triad cables where individually shielded conductors / pairs / triads are layed to form a multi core / pair / triad cable.

II. TAPED / SCREENED:

Aluminum bonded polyester tapes are wrapped along with a drain wire ( flexible tin plated copper wire rope ) in continuous contact with the aluminum side of the tape which is wrapped with an overlap of at least 20% creating a virtual screen.

III. DOUBLE SHIELDED:

In certain data networks the cable is double shielded i.e.: has two shields : the conductor is shield with Aluminum tape and overall shielding of the cable is done by copper braid shield. Here both the drain wire and outer copper shield is connected to ground or common mode to get best shielding results.

Shield chart ( suggested ):

Cable
Shield type
Shield wire/tape
Coverage
PTFE
Braided
Silver plated copper wire
90%
Silicon
Screened
Aluminum polyester tape
120%
Fibre glass
Braided
Tinned copper wire
70 to 90%
PVC/XLPE
Taped / Double shield
Aluminum polyester tape + Braided
120%


'High Temperature shielded ( varnished ):


Individual conductors are insulated with fibre glass braid and constructed jacket with fibre glass braid. A high temperature saturant improves abrasion resistance. A silicon saturant is also available on special order.
For details see Fiber Glass / Asbestors


Mechanical Shield:


Cables are armoured with an overall braid of Stainless Steel / Galvanized Steel wire to add high resistance to abrasion and mechanical damage and superior tensile strength. It is especially valuable in application where wire must undergo longitudinal stress such as those encountered in long vertical runs. These over braids furnish a minimum coverage of 85% and can be done on all types of cables.

 

MULTI CORE INSTRUMENTATION & CONTROL CABLES:


Prestige' Instrumentation & control cables are made as per customer requirements based on various parameters, with the choice of multipair construction, pair identification & proper shield to avoid electrical interface disturbances.

 

Cable
Conductor type
Wire Plating
PTFE
Stranded / Solid
Silver / Nickel plated copper wire
Synthetic
Rubber
Bunched / Solid
Tinned copper wire
Fibre glass
Bunched / Solid
Bare /Tinned copper wire
PVC/XLPE
Bunched / Solid
Tinned copper wire

Standard Characteristics of Instrumentation Cable

Test
0.5
0.75
1.0
1.5
2.5
Sq.mm
Sq.mm
Sq.mm
Sq.mm
Sq.mm
Mutual capacitance core to core(max).pF/metre <
250
250
250
250
250
L / R ratio (max). µH/Ω<
25
25
40
40
40
Conductor resistance @ 20°C. Ω / kM<
39.7
26.5
26.5
12.3
7.41
Insulation resistance Meg Ω / kM >
100
100
100
100
100
Core to core / screen / armour -
Resistance for 1 hour @ 20°C. Meg Ω / kM>
10
10
10
10
10
Screen to screen resistance -
1 hour @10°C. Meg Ω / kM>
1
1
1
1
1

MULTIPAIR THERMOCOUPLE EXTENSION / COMPENSATING CABLES

A Thermocouple measuring point is formed by joining two dissimilar metals as one circuit, which when exposed to different temperatures generates a net thermal electromotive force ( E.M.F.) Each thermocouple cable has two cores of such dissimilar conductors forming a pair and for multiple measuring points multi pair cable is used.
'Prestige' offers the complete range of cables suited for High Volt & Temperature application with various combinations of different conductors, insulations and shields as as per customer application & requirement.


INSULATION CHART
Material
Operating temp
PTFE
260°C
Synthetic Rubber
180°C
Fibre Glass Braid
250°C
XLPE
90°C
HRPVC
85°C
General Purpose PVC
70°C