The characteristics and quality of PTC elements directly determine the performance of PTC heater products. At present, the PTC heating elements commonly used in thermostatic heater products such as heater are high-temperature PTC elements, and the Curie temperature is higher than 120 ℃. Compared with low-temperature PTC elements, high-temperature PTC elements have great differences in manufacturing process and performance parameters. Good PTC characteristics are the basis of obtaining good heating performance.
Therefore, the following parameters should be considered when selecting PTC heater elements:
(1) Normal temperature resistance R25: for 110 ~ 220V voltage, R25 is generally 100 Ω ~ 10K Ω, and for 6 ~ 24V, R25 is 0.5 ~ 5 Ω. Generally, R25 is small, the initial current is large, the heating is fast, and the power is also large. But the withstand voltage ability is poor.
(2) The Curie temperature Tc should be moderate: under certain conditions, increasing TC can correspondingly increase the power consumption of the heater, but too high Tc (greater than 260 ℃) makes the electrode of PTC element easy to age, significantly shorten the service life, and often accompanied by thermal breakdown. Therefore, PTC heating elements with Curie temperature below 260 ℃ are generally selected.
(3) High withstand voltage: at least twice the service voltage to prevent electric breakdown.
(4) The resistance temperature coefficient should be large: generally greater than 14, so as to ensure that it is less affected by the change of ambient temperature.
(5) The initial impulse current shall be moderate: generally, the impulse current shall be less than twice the stable working current.
