Design

Common specifications for an electrical panel heating include:

  • heating a medium or mass in a given time
  • maintaining this temperature
  • ensuring a homogeneous temperature distribution

 

Procedure

 

Estimating the Power

The power required depends primarily on the insulation of the system or on the heat conduction properties of the matrix. If the heat generated in the Knitted Heating Fabric is well dissipated, the heating can also be operated with higher electric power without thermally overstressing the components. A first approximative value for the maximum output of tool heatings in the composite industry is 1000 - 1500 W/m².

 

If you know the area to be heated you can calculate the required power of the power supply unit.

 

Selecting the Power Supply Unit

Small heating areas (max. 1,5 m²) tend to have small resistances. According to the formula

this means achieving high heating power even at low voltage (DC voltage up to 60V).

 

CoTexx® Knitted Heating Fabric may be operated at higher voltages, but this requires increased security precautions. The advantages of a higher voltage include high heating powers for large resistors, low ohmic losses in spite of relatively small conductor cross-sections in the input leads and inexpensive power supplies, for example by using phase controls. At an operating voltage higher 50V AC or 70V DC the security policies of the Low Voltage Directive must be complied. It is recommended to install own circuits for the connected heaters, which are fused separately via earth leakage circuit breakers.

 

For many applications, which dispense with a complex temperature control, the use of laboratory power supplies offers an alternative. They are inexpensive and can be controlled precisely.

 

Based on the maximum values of current and voltage, it is possible to calculate the optimum resistance of the heater, in which the maximum power is achieved, by using Ohm's law.

 

Arrangement of Knitted Heating Fabric Webs

For this purpose, several iterations are necessary.

 

The first step is to determine the length of the knitted heated fabric which is necessary to cover the entire surface to be heated. Available standard widths as well as the electrical resistance per meter are listed in "Technical Data".

 

The simplest design variation is the connection in series of all webs. By adding the individual resistances yields the total resistance.

 

Is this resistance too high and the maximum power is thus not achieved at a fixed voltage, the resistance can be reduced by parallel connection of multiple heating panels. To ensure that all circuits produce the same amount of heat, all fields must have the same resistance. In addition, the width of the knitted webs can be varied.

 

Feel free to contact us for further information
hotline: 0800 6677373
telephone: +49(0)8259 8287-81
info@cotexx.com