ELECTRONIC CHOKE VS ELECTRICAL CHOKE

Actually electronic ballast is preferred via electrical ballast
      Hello readers, Today i'm here with a completely new topic.  Many of them find that electronic ballast or chokes are used in tube lighting nowadays.  Most of them wondered what is wrong with the oldest type of choke.  Let us see the detailed information of both in this article.

click this text to learn more about the magnetic circuits.

PARTS IN TUBE LIGHT:


  • BALLAST
  • STARTER(ELECTRIC TYPE)
  • SWITCH
  • DISCHARGE TUBE



TUBE LIGHT WORKING:
       Actually a tube light working involves in the following process:

  1. When we switch on the tube light the maximum current flows across the tubelight via the ballast and the starter.  At first no discharge happens thus no output is obtained.
  2. At first we can see a glow in the starter this is because the gases in the starter starts ionising due to the maximum voltage and hence the bimetallic strip melts and conduction to the tube starts.
  3. Then the voltage gradually decreases since the voltage drop is created in the ballast which is an inductor, again it breaks away from the fixed contact and high surge of current flows through the tube light.
  4. Gas discharge in the tube light thus got achieved.  The current instead of going through the starter goes through the tube because tube light has low resistance when compared to that of the starter.  
  5. Thus discharge of mercury produces ultraviolet radiation which in turn excites the phosphor powder coating in the tube light thereby delivering the white visible light
  6. Thus after the ignition of the tube light starter can be removed from the tube light since it is inactive. (P.S starter is only used for electrical ballast type tube lights not in the electronics type)
MAGNETIC BALLAST WORKING:

          Actually a magnetic ballast or electrical type ballast is an inductive coil.  It will look like a transformer but this is not transformer.  It is just some copper wire wounded over the core material which makes it look like a transformer.  Generally inductors are known for opposing any change in input current passing through them since it has lagging power factor and thus it is used in this circuit.
           Actually as seen in the working of the tube light the electrodes should be at a high temperature for a tube light to start.  During this initial position the ballast will oppose the input current from the mains since at first it goes straightly into the starter and preventing damage.  The starter which is in series with the ballast works as a switch which is initially in on condition after the current exceeds the rated current value the starter material melts and becomes open circuit.

           Thus leading the current passing through the tube light.  The high current produced for discharge is created by the opposing current stored in the inductor.  Thus lighting the circuit. Due to the presence of air medium the current through it ionizes and resistance decrease progressive thus the current goes on increasing.  The inductance coil now acts as a reactive load and limits the current as mentioned anove.

          Since magnetic ballasts are not as sophisticated as electronic ballasts and can be problematic, they are being replaced by the electronic versions. Magnetic ballasts are found in the light socket in between the plug for the light bulb and the power cord.

           In magnetic ballasts, current flows through coils of copper wire before moving on to the light bulb. Most of the current gets caught in the magnetic field it generates, with only small increments moving on to the light bulb. The current that is passed on depends on the thickness and the length of the copper coil. This inconsistent flow of the current is what causes the lights of the lamp to flicker and also creates the buzzing sound.


       The magnetic ballast method creates a huge amount of inductive reactive power, simultaneously exceeding the magnitude of active power, but this reactive power can easily and cheaply be compensated without risk of any interferences.



ELECTRONIC BALLASTS:
     
            Electronic ballast is given with our conventional A.C source with 220V at  50 – 60 Hz Frequency. The electronic ballast has a rectifier which first converts AC voltage into the DC voltage.  By using capacitors the DC current obtained from the rectifier is filtered.  The filtered D.C current is then passed through a series of induction coils that are separated from one another.Now filtered DC voltage is fed to the high frequency oscillation stage where oscillation is typically square wave and frequency range is from 20 kHz to 80 kHz. Hence output current is with very high frequency.


WORKING:
             As soon as D.C voltage is filtered by the capacitor configuration the D.C voltage is high frequency coils were the oscillation will depend on the input voltage and frequency.  A small amount of inductance is provided can be considered with the high rate of change of the current and high frequency generation in the electronic circuit.  The inductance formula is given by
                       
                                                    I=L(dI/dT)
             Generally more then 440+ voltage is required to glow.  when the switch is on the voltage across the lamp becomes 1000 v.  Once the discharge process exceeds the limited current will flow through the lamp and prevent short circuiting.  In a running condition of fluorescent lamp electronic ballast acts as a dimmer to limit current and voltage.

EMI FILTER:
It is used to block any electomagnetic interference once if any.

RECTIFIER:
It is used to convert A.C to D.C

HALF BRIDGE RESONANCE OUTPUT:
It converts dc to square waved voltage with high frequency.


A small amount of inductance is provided to be associated with high rate of change of current on high frequency to generate high valued . Generally more than 400 V is required to strike the gas discharge process in fluorescent tube light. When switch is ON, initial voltage across the lamp becomes 1000 V around due to high valued , hence gas discharge takes place instantaneously. Once the discharge process is started, the voltage across lamp is decreased below 230 V up to 125 V and then this electronic ballast allows limited current to flow through this lamp. This control of voltage and current is done by control unit of the electronic ballast. In running condition of fluorescent lamp electronic ballast acts as a dimmer to limit current and voltage.

The electronic ballast does not – or should not – produce substantial amounts of fundamental reactive power . The decisive argument put forward for its use is, however, the energy saving achieved, not so much by lower internal losses in the ballast itself, but rather by an efficiency improvement of the lamp when operated at the high frequency supplied from the output terminals of such electronic ballast. For this reason they feed less power into the lamp than a magnetic ballast does. However, electronic ballasts are several times more expensive than the plain passive magnetic models and much more susceptible to certain disturbances and are likely to become themselves a source of disturbances. Unlike the magnetic ballasts, which as a law of physics can follow only one principle of working and only one basic design, power electronics provide a lush choice of design variants and working principles to design electronic circuits for operating fluorescent lamps.

DIFFERENCE BETWEEN THEM:

Another difference is that electronic ballasts change the frequency of the electrical current without changing the voltage. While magnetic ballasts in fluorescent lamps work at a frequency of 60 hertz, electronic ballasts greatly increase that frequency to 20,000 hertz.

Due to such a high frequency, you will not see the lights flickering and will not hear a buzzing sound with fluorescent lamps using electronic ballasts.

Electronic Ballasts vs. Magnetic Ballasts
In addition to not flickering and being quieter than magnetic ballasts, electronic ballasts are preferred because it has many other advantages. They are smaller in size and weigh less. They are also great for the environment and your bank account because they are energy efficient and therefore lower your monthly energy bill.

Another advantage is that electronic ballasts can be used in lamps that are in parallel and series mode. If one of the lamps goes out, this will not affect the other lamps even though all the lamps are using the same ballast.

Also, if you want to replace your magnetic ballast with an electronic ballast, this is cheap and relatively easy to do.

10 REASONS WHY WE PREFER ELECTRONIC BALLASTS:

  1. It increases the lifetime of the lamp.
  2. Ballast loss is less and negligible most of the time.
  3. Weight is minimum
  4. Size is very minimum
  5. No startup vibrations
  6. No flicker in the tube
  7. No RF interface
  8. It creates low noise too
  9. Its only operates in supply voltage.
  10. The startup is instantaneous since the electronic choke is faster.

SEE THIS VIDEO FOR BETTER UNDERSTANDING THE CONCEPT OF BALLAST:




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2 June 2017 at 04:59 ×

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