Below given are the Technical Characteristics in manufacturing of cables:

1. Materials used in various types of cables
2. Insulation Material Properties
3. Resistance of Insulation Materials
4. Colour codes for Thermcouple Extension and Compensating Cables
5. Loop resistance for Thermocouple Conductors
6. Loop resistance for Copper Conductors

Click on each each of the above characteristic for more details.

1. Materials used in various types of cables

Instrumentation cable construction is of a very complex nature. There is a vast variety of sizes and construction used by various project consultants.

Listed below are various options available within cable constructions, allowing engineers to specify cables that are best suited to the application.

Conductor

Electrolytic grade, annealed plain or tinned copper, either solid or stranded. Thermocouple cables with matched pair of thermocouple alloys.

Insulation

Depending on conductor temperature, flame retardancy, electrical characteristics, compatibility and flexibility various insulating materials such as PVC, Polyethylene, XLPE, Silicon rubber, Mica tape etc.

Identification

Identification either by colour code and /or by no. printed tapes over pairs.

Electrical Screening

Electrical screening is provided over twisted elements and /or total cable to protect fidelity of the signal.

Inner Sheath

Material such as PVC, Polyethylene, FRLS PVC, LSF are used to serve as electrical bedding as well as chemical ingress barriers.

Armour

Galvanized steel wire or strips applied spirally over inner sheath or symmetrical or asymmetrical braid depending on final use of the cable.

Outer Sheath

The choice of sheathing material depends on the application requirements such as temperature, flame retardancy, smoke and acid gas emission limitations (Halogen free), resistance to chemicals and water, flexibility, exposure to UV and hazardous environment, anti-rodent and anti-termite properties. The materials used are PVC and Polyethylene LSF.

2. Insulation Material Properties

Insulation Material	Tensile strength	Elongation at break	Operating Temp.	Short Circuit Temp. Rating	Dielectric Constant	Dissipation Factor	Volume Resistivity
	N/MM²	%	C°	C°	10³Hz	10³Hz	Ω - Cm
PVC	>13	250	70	135	4~7	0.02~0.04	10
Polyethylene	>14	500	70	200	2.27	0.0003	10
XLPE	>15	500	90	250	2.3	0.005	10

POOR

FAIR

GOOD

Codes/Conductor combinations Characteristics of various standards of Extension and Compensating Cables			Colour code for Thermocouple Extension  and Compensating Cables
			British Standard BS 1843		American Standard ANSI MC 96.1		Indian Standard IS 8784		International Electro Technical Commission
Code	Conductor Combinations								IEC 584-3
	+ VE Leg	- VE Leg
KX	Nickel Chromium	Nickel Aluminium		+/- 2.5°C		+/- 2.2°C		+/- 2.2°C		+/- 2.5°C
VX	Copper	Copper- Nickel		+/- 2.5°C		2.2°C	-	-		+/- 2.5°C
TX	Copper	Copper- Nickel		+/- 1.0°C		+/- 1.0°C		+/- 1.0°C		+/- 1.0°C
JX	IRON	Copper- Nickel		+/- 2.5°C		+/- 2.2°C		+/- 2.2°C		+/- 2.5°C
EX	Nickel Chromium	Copper- Nickel		+/- 2.5°C		+/- 1.7°C		+/- 1.7°C		+/- 2.5°C
RX	Copper	Copper- Alloy		+/- 2.5°C		+/- 1.5°C		+/- 1.5°C		+/- 2.5°C
SX	Copper	Copper- Alloy		+/- 2.5°C		+/- 1.5°C		+/- 1.5°C		+/- 2.5°C
BX	Copper	Copper- Alloy	-	-		+/- 0.5°C		+/- 0.5°C	-	-

LOOP RESISTANCE (MAX) FOR THERMOCOUPLE CONDUCTORS at 20ºC OHM / Km.
THERMOCOUPLE   TYPE	KX	VX	TX	JX	EX	RX/SX
1)  20  AWG  Conductor	1910	980	980	1214	2312	280
2)  18  AWG  Conductor	1212	624	624	772	1470	175
3)  16  AWG  Conductor	746	385	385	475	905	110

LOOP RESISTANCE (MAX) FOR COPPER CONDUCTORS at 20°C OHM / Km.
SIZE IN SQ.MM.		0.5	0.75	18 AWG	1.0	1.5	2.5
Max. resistance at 20°C	Flexible Copper Plain Conductors	79.20	50.40	45.00	36.20	25.40	15.30
Max. resistance at 20°C	Solid Copper Plain Conductors	72.00	48.00	44.00	35.40	24.20	14.50