Development and research of flexible fabric electric heaters

FIGURE 4. Drafting plan and pattern card 
 
For the production of the investigated fabrics on the loom, 6 heald frames were used. Of these, 4 healdes for 
background threads, and 2 for electrically conductive threads. 
Samples of electric heating fabrics with a plain weave were developed. As a warp and a weft, electrically 
conductive and non-conductive threads with a linear density of 50 and 25x2 tex, respectively, were used. The density 
of the fabric on the warp is 210 ± 3 end/dm, and on the weft is 170 ± 3 weft/dm. 
The obtained prototypes of the electrically conductive fabric actually represent a cotton fabric of a plain weave, 
into which an electrically conductive bus is included at a certain distance along the warp and weft. Copper wires with 
a diameter of 0,15 mm were used as current-supplying electrodes, which were located in the warp at a certain distance. 
Depending on the capacity of flexible woven electric heaters, the main parameters of electrically conductive fabrics 
have been developed. (U = 12, 24, 36 and 220 watts) [6-8]. 
When producing woven flexible electric heaters, a special device for wire threads was designed on the machine in 
order to prevent the difference in the use of electrical insulating and current-supplying electrodes, as well as their 
crimp during fabric formation. 
In the weaving process, internal stresses accumulate in the warp and weft yarns, which relax in time. 
It can be assumed that the relaxation processes taking place will in a certain way affect the electrical properties of 
the fabric. 
The change in the electrical properties of the fabric over time is due to two factors: a change in the electrical 
resistance of the fabric itself and a change in contact resistance, as a result of an improvement or deterioration in the 
contact between the electrically conductive yarns and the current-carrying electrodes. The number of microwires in 
the electrodes on the fabricated flexible electric heaters was equal to 10. The electrical resistance of the fabric was 
measured by the 2
th
and 4
th 
electrode method. 
It is known that with a 2
th
-electrode method, the measured electrical resistance is the sum of the resistance of the 
material sample and the contact resistance. 
The 4
th
-electrode method allows you to exclude contact resistances and measure only the resistance of the material 
sample. It is based on direct passing of a stabilized direct current of a certain value through a material sample and 
measuring the voltage drop in a given section using a digital voltmeter with a high input impedance (more than 10
6
Ohms). 
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