Dielectric heating (1).pptx - DIELECTRIC HEATING \u2022Dielectric heating is also called high-frequency capacitive heating \u2022 It is used for heating

Dielectric heating (1).pptx - DIELECTRIC HEATING...

This preview shows page 1 - 6 out of 18 pages.

DIELECTRIC HEATING Dielectric heating is also called high-frequency capacitive heating. It is used for heating insulators like wood, plastics and ceramics etc. which cannot be heated easily and uniformly by other methods. The supply frequency required for dielectric heating is between 10-50 MHz and the applied voltage is up to 20 kV. The overall efficiency of dielectric heating is about 50%.
Image of page 1
DIELECTRIC HEATING
Image of page 2
DIELECTRIC HEATING When non – metallic parts such as wood, plastics are subjected to an alternating electrostatic field dielectric loss occurs. In dielectric heating these losses are made use of. The material to be heated is placed as a slab between metallic plates or electrodes connected to a high frequency AC supply. For producing sufficient heat, frequency between 10 and 30 MHz is used. Voltage applied will be in the range 600V – 3kV.
Image of page 3
DIELECTRIC HEATING The current drawn by the capacitor, when an ac supply voltage is applied across its two plates, does not lead the supply voltage by exactly 90 0 . There is always an in phase component of the current. Due to the in phase(active) component of the current, heat is always produced in the dielectric material placed in between the two plates of the capacitor. The electric energy dissipated in the form of heat energy in the dielectric material is known as dielectric loss. The dielectric loss is directly proportional to the frequency of AC supply given to the two plates of the capacitor. The dielectric loss is the molecular friction in the dielectric material when an AC electrostatic field is applied to it.
Image of page 4
DIELECTRIC HEATING Since insulators are poor conductors, they cannot be heated quickly from outside. In dielectric heating, the heat is produced within the material itself. The heat generation is uniform, therefore the dielectric material is heated uniformly.
Image of page 5
Image of page 6

You've reached the end of your free preview.

Want to read all 18 pages?

  • Fall '14
  • H N SHANKAR

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes