How an Electric Iron works and what’s inside it? (with live preview)

Hey guys if you ever wondered why an electric iron turns on and off all by itself, then you are at the right place. Because in this post You will see teardown of an old Electric iron, what’s inside it and learn how it works.How an Electric-Iron works and what’s inside it?

I had this old – very old electric iron for a long time now. So for science, I am going open it and show you how actually does an Electric iron works.

 

Components inside an Electric iron are:

 

 

 

 

1. Thermostat:

 

 

  • Thermostat in an electric-iron is a device which changes its orientation or something like this according to the temperature.
  • This thermostat consists of a Bi-metallic strip. And as the name itself suggest, Bi-metallic means two metal strips.
  • Each of the two strips has a different ‘coefficient of thermal expansion’. One has higher whereas other has a lower coefficient of thermal expansion. So that one bends more than the other metallic strip at any particular temperature.
  • At higher temperature, Metallic strip 2 bents and pushes the Metallic strip 1 upward to a position where the electric connection between strip 2 and live wire breaks and Electric iron gets turned off (See image below)

 

 

 

2.  Heating element:

 

 

  • Heating element is the heart of any electric iron. It consists of a nichrome wire inside of a mica sheet.
  • This nichrome wire heats up as current passes through it due to I^2R loss. So longer the time of flow of current through it, more will be the heating of the Heating element.
  • Mica is chosen as a cover in a heating element because: (a) It is a very good insulator and (b) It can withstand a very high temperature.

 

3. Turning knob or tightening-screw:

 

 

  • Using this knob, we can adjust the temperature of the electric iron according to our need.
  • This knob is connected to a screw which controls how hard the contact or upper metallic strip must bend to separate and break the electric connection so that Electric iron gets turned off.
  • This means if I keep turning the screw, then the temperature required to bend this upper metallic strip also increases or you can say temperature required to break the electric connection increases.

4. Neon bulb:

  • This bulb is used as an indicator for Electric iron.
  • It is connected in parallel to the heating element.

 

Working:

**Watch the video given above to see the Electric iron in action

  •  Electric iron is connected to the power supply.
  • Neon bulb gets light-up indicating the start of heating process in the heating element.
  • Let’s say knob is at its lowest position. In this case, as soon as the temperature of strip 2 rises to100 degrees(let’s say); it bends enough to break the electric connection between strip1 and the live wire.
  • Now the electric iron is off.
  • After some time, strip 2 contracts to its original position and thus the electric connection is made again causing Electric iron to turn on.
  • Now let’s say knob is at its uppermost position. In this case, as soon as the temperature of strip 2 rises to 200 degrees(let’s say); it bends enough to break the electric connection between strip1 and the live wire.
  • Now the electric iron is off.
  • After some time, strip 2 contracts to its original position and thus the electric connection is made again causing Electric iron to turn on.

 

 

 

 

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