PTC Heater Facts

Reference Temperature:

The temperature point at which the PTC begins to self limit. The higher the reference temperature, the higher the power potential. This temperature is measured in the composition of the ceramic material.

Application Temperature:

The temperature relationship of the various elements within the application. Nominal application temperatures are when all these elements are at stabilized temperatures and when they are in balance with one another. This temperature changes as heatsink environment changes. This is the temperature that the PTC controls by self regulation.

Heatsink Environment:

The conditions of the environment that would affect the heater's ability to transmit heat and that would influence the application temperature. On an air heater example this would mean: air flow, material masses within the application, open or closed systems and ambient temperatures.

PTC Stone:

Synonyms are stones, pills and ceramic. The size, reference temperature and number of stones determine the power potential of the element.

Self Regulation:

The PTC automatically adjusts resistance in an effort to maintain the highest possible power output that the heatsink environment will permit. The energy being supplied to the PTC is balanced with the thermal energy being dissipated into the heatsink environment. Temperature is regulated when an equilibrium is reached.

Dynamic Range:

The actual wattage range of the element in application, derrived from the heatsink environment. For example: A HR09 air heater could be capable of a dynamic range from 700 to 100 Watts or less. The element is able to produce 700 Watts in good heatsink environment. If airflow velocity suddenly fell to zero, the element would safely self limit to around 100 Watts. Similarly in extremes of ambient temperature, the elements actual wattage might reduce to 600 W or increase to 900 Watts. The dynamic range is application specific. Each application, with it's unique airflow and ambient air temperature characteristics, will result in a different dynamic range.

PTC Positive
Temperature Coefficient:

As temperature increases so does the resistance of the element.

Temperature Control:

The PTC element controls application temperature by automatically adjusting it's power output as needed. The capacity of heatsink environment influences the power output of the heater and therefore the application temperature. Wattage ultimately determines temperature in the application. The benefit of the PTC is that it will maintain a stabilized power/temperature output with any constant heatsink condition. In the event that the target temperature is not being achieved or is too low, the element could be made larger to increase wattage, or for example on an air heater application, the air flow could be slowed down to increase the exit air temperature. Controls can be eliminated as long as the element can respond to all heatsink conditions within it's dynamic range potential to maintain the target temperature within the accepted tolerances.

Power:

Watts

Inrush Current:

Maximum current that occurs for a few seconds after switching on. Inrush current does not depend on ambient heatsink, it depends on applied voltage.