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What are PTC, Positive Temperature Coefficient, Heaters?

What are PTC, Positive Temperature Coefficient, Heaters?

Posted by Adelle Webber on

Positive Temperature Coefficient (PTC) Heater

Electrical & mechanical design Engineers have been using “Positive Temperature Coefficient” heaters in the equipment for years.  They recognize the unique properties of the PTC heaters that make them more reliable, safer, cost-effective than traditional resistance wire type heaters.  Consider the PTC heaters compared to resistant heaters as LED light bulbs are to incandescent bulbs.  They have comparable lower energy costs and a longer life.

What is Positive Temperature Coefficient?

If a material exhibits a positive temperature coefficient means that as its temperature increased its resistance to current raises proportionately.  Initially, the current through these devices will rise sharply with the low resistance but then decrease to zero when the design temperature is reached.  During manufacturing these devices are made to reach a specific temperature.

Ceramic Material Instead of Resistance Wire

Typical heating elements that use a resistance wire to generate heat, PTC heating elements are made as ceramic stones, based on barium titanate. These manufactured ceramic stones have very unique characteristics as semiconductors whose properties can be precisely determined during their design and manufacture.  PTC devices do not burn oxygen making them safer to used in controlled environments.  This also makes them more energy efficient.

 

How are PTC Devices Unique?

PTC Heaters cannot overheat. These unique factors make the devices self-limiting when their resistance increases the current through the device decreases.  They can also be considered self-controlling.  If the ambient temperature starts to decrease, the heater's resistance will decrease drawing more current and countering the cooling tendency. Conversely, any tendency to increase its temperature has the opposite effect.  Convection heaters do not have these characteristics.

The Curie Point

The PTC ceramics can be manufactured to have different fixed temperatures at which this dramatic resistance change takes place. This temperature point is called the Curie point of the PTC heater.  This point is the temperature control for the heater.

More Flexibility In Manufacturing

PTC heaters can be designed to operate at temperatures between -40F and 158F making them suitable for a wide array of equipment design applications.  The material used can be manufactured in unlimited shapes and sizes.  Custom shapes can be designed for specific applications.  The PTC material can be machined, drilled, bent, and shaped.

DBK’s Off-The-Self Products for Equipment Design Engineers

DBK’s line of products incorporates many of these characteristics into standardized off-the-shelf selections of shapes, sizes, and wattage. 

  • PTC Fan Heaters couple the devices with fans to better direct the heat within enclosures.
  • PTC Convection Heaters leverage heat exchanging fin structures to distribute the heat evenly without fans or other moving parts.
  • PTC Cartridge Heaters are embedded in silicone creating excellent heat transfer characteristics and high thermal efficiency.
  • PTC Surface Heaters utilize aluminum housings for highly effective heat transfer to flat surfaces.
  • HRKK PTC Air Heaters are designed with finned resistor heating elements that ensure balanced heat transfer with low airflows.
  • RFHSS Electromechanical Hygrostats are designed to control the relative humidity inside electronic enclosures.

DBK’s Thermostats are compactly designed for use inside electrical cabinets where additional temperature controls are needed.


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