What is the purpose of a choke in a tube-light?

Forums Common electrical queries What is the purpose of a choke in a tube-light?

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  • #639 Reply

    Pradip
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    Why there is always a choke used with tubelights? What is the function of it? What will happen if a tubelight is directly connected across power supply without any choke?

    #642 Reply
    Profile photo of Dnyanesh
    Dnyanesh
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    First of all let’s see how starting process of fluorescent tube light is done.

    Fluorescent tube light has the choke( controls current flow), a starter (helps choke to increase emf), and a fluorescent tube(containing inert gas and Mercury).

    1. Ac current switches its direction every 1/50 th sec; as current goes through filaments inside the tube they goes heat up.

    2. Inside the starter there is a bimetallic switch operates when heat up by continue flow of current and open circuit the starter.

    3. The sudden open circuit of starter make magnetic fields collapse in choke.  Which results in high emf. (it is also known as Inductive Kick).

    4.This high  voltage heat up the mercury which in turn helps in ionization of inert gas. As ionization takes place tube become conductive and current starts  flowing through tube and starter is now open circuited.

    5. As mercury heats up more current starts flowing more in the tube which makes tube glows brighter.

    Now here we come to your answer, what will happen if we don’t use choke?

    As I mentioned in point 5 heating of tube is proportional to flow of current.

    Here choke is use for limiting the current to enough amps just to continue glowing the tube.

    If we don’t use choke the current will not limit as without choke circuit will become short circuit (refer to fluorescent tube light circuit) and it may results in break down of tube.

    So, the conclusion is choke behaves like inductor in the circuit. It manages flow of current and prevent the circuit from short circuit.

    So,  its not recommended to connect the tube without choke.

    Hope this’ll help you.

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