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Why Use PTC Ceramic Heating Elements?

Why Use PTC Ceramic Heating Elements?

Posted by Adelle Webber on

PTC Ceramic Heating Elements are Unique in Industrial Heating.

microscope in PTC lab

Industrial heating brings to mind huge furnaces, pouring hot lava-like metal, and long annealing ovens, but there is another subset of heating elements not talked about as often. The subset or point heating applications are lower temperatures and wattage than the larger heating furnaces. 

The smaller applications require less voltage and electricity but require precise temperature control at all times.  Positive temperature coefficient PTC heaters are ideal for these applications.

The tolerance for heating variations is much less than a 2,200 degree F metal or glass furnace. These applications require precise temperature control in mostly enclosed cabinets or other electronic devices. A medical device that must remain at a given temperature doesn't have room for elaborate control circuits, but controlling the temperature is crucial. 

Remote SCDA systems where electronics and controls need protection from extreme environments is another example. The PTC ceramic heating elements provide an ideal solution for both applications.

What does PTC Heater Mean?

PTC, Positive Temperature Coefficient, identifies the characteristics of the ceramic element. As the temperature of the ceramic device goes up due to a current flowing through it, the resistance increases. When a predesigned temperature approaches, the resistance of the circuit goes to infinity, effectively shutting off the current and heat.

This predefined control circuit adjusts to the ambient temperature of the surrounding air and limits the heat required to bring the unit to the set temperature. When the outside temperature is low, the lower the resistance of the circuit. More current, the temperature increases until reaching the set-point and the device shuts off.

An NTC, negative temperature coefficient device works oppositely. As the temperature goes up, the resistance in the circuit goes down.

Resistance wire, they type we see in many heaters, works on a different principle. When current is flowing through the wire, the resistance in the wire creates the heat. A separate device does control of the current in the circuit that senses temperature and restricts the flow of current. 

In some instances, a rheostat decreases or increases resistance to the circuit lowering the current and the heat. The actual resistance to the electrical current of the wire does not change.

What is the Electrical Formula for PTC?


electrical formula for PTC

A simple approach for you, amateur electrical engineers, Current = voltage/resistance, or 

I = V/R.  

Voltage is constant and stays the same. If the resistance of the circuit goes up, the current goes down or a positive coefficient.

Power or P = I X V or current times voltage. If voltage is again constant, then the power generated that produces heat is a function of the current.

More current more power and more heat. Less current, less energy, and less temperature.

If more heat or higher temperatures are needed, more voltage or current is required. Usually, the energy is determined by the available circuit voltages in the panel or device.

 

How are the PTC Ceramic Elements Made?

The ceramic materials are doped using barium titanate in a laboratory to create the precise temperature threshold required.  The heater can be designed for a specific application and temperature. For a more complete explanation read the post What is PTC, Your definitive guide to the PTC manufacturing process.

Are PTC Heaters Cheap to Run?

These heaters are highly energy efficient. Technically if a circuit uses no more electricity than necessary to reach a set temperature, the cost to run it would be less. Plus, there are no extra devices needed to control the temperature, which reduces costs. Base on those two factors, yes, PTC heaters are cheaper to run.  They are less costly than the typical resistive heater.
These heaters are very cost-effective to install and operate with little no maintenance required over the useful life of the device.  There is no better way to generate heat at lower costs for an industrial type of application.

Are There Different Types of PTC Electric Heating?

These self-regulating heaters are customarily prewired at the manufacturer and installed on other devices. The manufacturer ensures the quality and electrical isolation of the connections. The ceramic components are small and difficult to install without specialized tools.
Coupling the devices with the right heat transfer devices requires expertise taking advantage of design elements for different applications. This expertise and knowledge come from thousands of various installations under all types of environmental conditions. 
Their application type can identify the types of heaters using PTC Ceramic Elements.

Fan Heaters

The heating elements are mounted in the housing with a fan that blows air across the elements. This helps transfer the heat into a larger space. A home space heater containing a fan is a good example of how this type of heater works.

Convection Heaters

In this case, the heating element is attached to aluminum fins mounted in a cabinet such that the natural flow of air by convection circulates the heat generated by the element. This type of device would be mounted at the bottom of a cabinet heating air as it entered the bottom creating a natural flow and minimizing condensation from the outside air.

Surface Heaters

Designed with aluminum housing and attached directly to the surface of the component to be heated it transfers the heat from the ceramic element across the surface of the heat sink and attached surfaces.

Cartridge Heaters

Cartridges are similar to the elements that are placed in a hot water heater or another container where the contents need to be heated. The cartridges are sealed to the elements or liquids to be heated and inserted into the container. Outside leads connect to the electrical circuit inside. The temperature inside the container is limited to the design temperature of the PTC device in the cartridge.

Air Heaters

Similar to fan heaters but with special perforated surface areas that transfer the heat efficiently to air passing over the surface areas.
Each type or group have their characteristics making them more efficient for that specific application. When in doubt of what kind of component or device is right for your use, it is best to contact the experts.  Custom PTC heating elements can be manufactured for your specific application.

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