.:: Welcome to Multicab Corporation ::.

Instrumentation

Triad & Quad Cables for Resistance Temperature Detector (RTD):

The electrical resistance of metal changes with temperature. This property is nowadays usedfor temperature measurements in industry. Of all usable metals platinum has found the most acceptance as :

It can be highly refined.
It resists contamination
It is mechanically and electrically stable over a large range oftemp.
The relationship between temp. and resistance is quite linear.
Drift and error with age and use are negligible

Due to its higher electrical output, Platinum Resistance Temp. Detector (RTD) furnishes an accurate input to temp. indicators,controllers,recorders,scanners, data-loggers and computers. It is used forTemp. measurement in the range -220 to 600 C. The max. temp. is determined by the type of insulation material used to enclose the platinum winding.

The most commonly used RTD is PT-100. The sensing element is made of platinum wire and itsresistance at 0 C is 100 Ohms.

Generally the resistance of the RTD forms an arm of the bridge circuit to measure the temperature as under

This configuration is used where the distance between the RTD and the measuring instrument is small and high accuracy is not required. Here a pair (2 core) cable is used for connectionIn a process plant there may be quite a distance between the RTD and its indicator. The resistances oflead wires and the change in them due to change in surrounding temp .may add to an error in themeasurement

To take care of lead wire resistance and the change therein due to change in ambienttemperature,three wire RTD is used and the connection ofthe same in the bridge circuit is as under.

This is the most commonly used and in this case a triad (Three Cores) cable is used for connecting RTD to the indicator/controller/recorder For very accurate readings either of the following circuits are used where a quad (Four Core) cable isused for connecting RTD to the measuring instrument.

Colour Code For Insulations

We provide colour code of Red, Yellow, Blue with number printing for core identification in triad cable. Some clients ask for Red, Yellow, Yellow or Red, Red, Yellow for identification. B.S. specification also does not specify any colour code for triad.

PVC/PE InsulatedOveraJl Shielded Triad Cables

Table details of conductors and insulation thickness
Norminal area of condector in sq m.m	Constrction details number/daimeter mm	Max resistance in o hm/km at 20 dag Multicore/multipair		Thikness of insutation in mm average/ minimum		Nominal core dimeter mm
0.50	7/0.30	39.0	39.7	0.6	0.44	2.20
0.75	7/0.37	26.0	26.5	0.6	0.44	2.50
1.00	7/0.43	18.1	18.4	0.6	0.44	2.60
1.50	7/0.53	12.1	12.4	0.6	0.44	2.80

Note: 1. Fortinned copper conductor ,the above resistance values will be higher by 0.6 %
2. As per International standards, which is also adopted by BIS and BS, the size of conductor is decided by its resistance only. The constructions of the conductor mentioned above and henceforth in this catalogue, are only indicative in nature. They may vary within the prescribed limits if any, laid by the standards.

12 Triad Overall Shielded Unarmoured Cable	12 Triad Overall Shielded Strip Armoured Cable

Dimensions of 0.5 sq mm multicore PVC/PE insulated Alu polyester tapped shield cables.

Number of Triads	ONE		TWO		FOUR		SIX		TEN		TWELVE
Cable type	Unarmd. Armd. Unarrnd. Armd. Unarmd. Armd. Unarrnd. Arrnd.								Unarmd. Arrnd. Unarrnd.			Armd.
Nom. Thickness of innersheath mm		0.80		0.80		0.80		0.80	1.00	1.00	1.00	1.00
Diameter over innersheath mm		6.40		11.2		12.5		15.4	18.0	18.0	19.5	19.5
Size of G.!. Armour mm		0.90		0.90		0.90		4xO.8		4xO.8		4xO.8
Diameter over armour mm		8.20		13.0		14.3		17.0		19.6		21.10
Nom. Thickness of oversheath mm	0.90	1.40	1.00	1.40	1.00	1.40	1.10	1.60	1.40	1.60	1.40	1.60
Nom. overall diameter mm	6.70	11.0	11.5	15.8	13.0	17.10 16.0		20.5	20.8	23.0	22.5	24.5
Normal Delivery Length +/- 5% Mtr	1000	1000	1000	1000	1000	1000	1000	1000	1000	.500	500	1000

PVC/PE Insulated Overall Shielded Triad Cables:

Dimensions of 0.75 sq mm multicore PVC/PE insulated Alu polyester tapped shield cables.

Number of Triads	ONE		TWO		FOUR		SIX		TEN		TWELV
Cable type	Unarmd. Armd. Unarmd. Armd.				Unarmd. Armd. Unarmd. Armd.				Unarmd. Armd.		Unarmd. I
Nom. Thickness of innersheath mm		0.80		0.80		0.80		0.80	1.00	1.00	1.00
Diameter over innersheath mm		7.00		12.3		14.0		17.0	20.0	20.0	21.7
Size of G.!. Armour mm		0.90		0.90		4x 0.8		4xO.8		4 x 0.8
Diameter over armour mm		8.80		14.1		15.6		18.6		21.6
Nom. Thickness of oversheath mm	0.90	1.40	1.00	1.40	1.10	1.60	1,10	1.40	1.40	1.60	1.60
Nom. overall diameter mm	7.20	11.60	12.8	16.9	14.6	19.0	17.7	22.0	22.8	25.0	25.0
Normal Delivery Length +/- 5% Mtr	1000	1000	1000	1000	1000	1000	1000	1000	500	500	500

Dimensions of 1.00 sq mm multicore PVC/PE insulated Alu polyester tapped shield cables.

Number of Triads	ONE		TWO		FOUR		SIX		TEN		TWELVE
Cable type	Unarmd. Armd. Unarmd. Armd.				Unarmd. Armd. Unarmd. Armd.				Unarmd.	Armd.	Unarmd.	AI
Nom. Thickness of innersheath mm		0.80		0.80		0.80		0.80	1.00	1.00	1.00	1.
Diameter over innersheath mm		7.20		12.6-		14.4		17.5	20.50	20.5	22.0	2:
Size of G.!. Armour mm		0.90	0.90			4xO.8		4xO.8		4x 0.8		4
Diameter over armour mm		9.00		14.4		16.0		19.1		22.1		2
Nom. Thickness of oversheath mm	0.90	1.40	1.00	1.40	1.10	1.60	1.10	1.40	1.40	1.60	1.40	1.
Nom. overall diameter mm	7.50	11.8	13.0	17.2	15.0	19.4	18.0	22.5	22.3	25.5	25.2	2i
Normal Delivery Length +/- 5% Mtr	1000	1000	1000	1000	1000	1000	1000	1000	500	500	500	5C

Dimensions of 1.5 sq mm multicore PVC/PE insulated Alu polyester tapped shield cables.

Number of Triads	ONE		TWO		FOUR		SIX		TEN		TWELVE
Cable type	Unarmd. Armd. Unarmd. Armd.				Unarmd. Armd. Unarmd. Armd.				Unarmd.	Armd.	Unarmd.	AI
Nom. Thickness of innersheath mm		0.80		0.80		0.80		0.80	1.00	1.00	1.00	1.1
Diameter over innersheath mm		7.60		13.5		15.2		18.8	22.0	22.0	24.0+	24
Size of G.!. Armour mm		0.90		4xO.8		4xO.8		4 xO.8		4xO.8		4:
Diameter over armour mm		9.40		15.1		16.8		20.4		23.6		25
Nom. Thickness of oversheath mm	0.90	1.40	1.00	1.60	1.10	1.60	1.40	1.60	1.60	1.60	1.60	U
Nom. overall diameter mm	7.80	12.2	14.0	18.5	16.0	20.2	20.0	23.8	25.2	27.0	27.2	29
Normal Delivery Length +/- 5% Mtr	1000	1000	1000	1000	1000	1000	1000	500	500	500	500	50

Thermocouple Extension and Compensating.Cables:

It was observed that when a junction of two dissimilar metals is heated., an emf is generated and it is Proportional to temp.difference between the hot junction and the point where it is measured. This principle is now universally used in the industry to measure and control the temperature in process.The junction is known as Thermocouple.The following junctions i.e Thermocouples have been standardised the world

Code	+ ve Leg	- ve Leg	EMF at 100°C in milli volt ref. jn at 0°C	Recomended Remarks working temp in celsius
K	Chromel (alloy of Chromium & Nickel)	Alumel(alloy ofAluminium& Nickel)	4.09	O°C to 1100°C Most commonly used
T	Copper	Constantan(alloy ofCopper & Nickel)	4.28	-185°C to 300°C For low temp. & cryogenic applications
J	Iron	Constantan	5.27	20°C to 700°C Used in reducing Atmosphere
E	Chromel	Constantan	6.32	O°C to 800°C Highest EMF output
R	Platinum+ 13% Rhodium	Platinum	0.647	O°C to 1600°C Very high temp measurements
S	Platinum+ 10 % Rhodium Rhodium	Platinum	0.645	O°C to 1500°C Very high temp. measurements
B	Platinum+ 30 % Rhodium	Platinum + 6 % Rhodium	0.033	100°C to 1500°C Mainly used in glass industry

1 I 2 I 3 I 4 I 5

top