Wire, Cable and Tubing Solutions from Alpha Wire Company

THERMOCOUPLE WIRE AND CABLE

TEMPERATURE MEASUREMENT AND CONTROL

The measurement of temperature is one of the most vital functions in the control of manufacturing and processing operations. As demands for greater quality, reliability and economy increase, the demands for more precise measurement and control increase. Newer and more sophisticated electronic circuitry is employed creating stringent demands on the wire and cable used to sense and transmit temperature measurements. To meet these ever-increasing demands, Alpha has a full-line of Thermocouple Grade Wire and Thermocouple Extension Wire and Cable. Complementing its line of Electronic Instrumentation Cable, Alpha now provides the industry with a complete line of wire and cable for manufacturing and process control, all produced to the highest standards of reliability and safety established by the government and industry.

THE THERMOCOUPLE

At the heart of all temperature measurements is the thermocouple. Although involving very complex design parameters, the fundamental concept of all thermocouples is the same. Two wires of dissimilar metal are joined together at one end. An increase in temperature creates an Electrocmotive Force (emf) or signal, which is transmitted through these wires to a monitoring device which "reads" this signal and displays it on a previously calibrated meter or Digital device.
The monitoring device is usually at a location some distance away from the actual thermocouple. To connect the thermocouple to the monitor requires wire or cable (for multiple thermocouple installations) that will maintain the integrity of the temperature-emf signal generated by the primary wires in the thermocouple.

CONDUCTOR MATERIALS

The range and accuracy of temperature measurement are dependent on the conductor materials employed. Pairs of various metal alloys will react differently with changes in temperature.
Chart (1) gives the temperature range and limits of error (tolerance) for the most popular alloy combinations. All Alpha thermocouple wire and cable is tested and calibrated to the standard limits of error as indicated. Where situations require closer tolerances, wire and cable calibrated to special error limits is available under special order.

LIMITS OF ERROR FOR THERMOCOUPLE GRADE AND EXTENSION WIRE^ CHART NO. 1

THERMOCOUPLE GRADE
ANSI Type	Material	Temperature Range °C	Standard Limits (±)	Special Limits(±)
J	Iron/Constantan	0 to 277 277 to 760	2.22°C 3/4%	1.11°C 3/8%
K*	Chromel/Alumel	0 to 277 277 to 1260	2.22°C 3/4%	1.11°C 3/8%
T	Copper/Constantan	-184 to -101 -101 to -59 -59 to +93 93 to 371	--- 2% .83°C 3/4%	1% 1% .42°C 3/8%
E	Chromel/Constantan	0 to 316 316 to 871	1.67°C 1/2%	1.25%°C 3/8%
R	Platinum 13% Rhodium/ Platinum	0 to 538 538 to 1482	1.39°C 1/4%	--- ---
S	Platinum 10% Rhodium/ Platinum	0 to 538 538 to 1482	1.39°C 1/4%	--- ---
B	Platinum 30% Rhodium/ Platinum 6% Rhodium	0 to 538 538 to 1482	±0.5% 1/4%	--- ---
THERMOCOUPLE EXTENSION
ANSI Type	Material	Temperature Range °C	Standard Limits (±)	Special Limits(±)
JX	Iron/Constantan	-18 to 204	2.22°C	1.11°C
KX	Chromel/Alumel	-18 to 204	2.22°C	1.11°C
TX	Copper/Constantan	-59 to 93	.83°C	.42°C
EX	Chromel/Constantan	-18 to 204	2.22°C	1.11°C
RX+	Platinum 13% Rhodium/ Platinum	24 to 204	6.67°C	---
SX+	Platinum 10% Rhodium/ Platinum	24 to 204	6.67°C	---
BX	Platinum 30% Rhodium/ Platinum 6% Rhodium	0 to 100	++	---

++Copper/copper compensating extension wires have no significant error in the 0 to 100°C range
^ The limits of error based on a of 0°C (32°F) per ANSI Circular MC 96. Percentages apply to actual temperature being measured.
+Copper/ Alloy #11 --- Compensating Extension Wires for Platinum/Platinum-Rhodium Thermocouples.
*Trademark, Hoskins Co.

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