Starting of fluorescent tube light by using inverter circuit instead of choke and starter arrangement

Manish Debnath Int. Journal of Engineering Research and Applications www.ijera.com
ISSN: 2248-9622, Vol. 5, Issue 11, (Part - 5) November 2015, pp.57-61
www.ijera.com 57|P a g e
Starting of fluorescent tube light by using inverter circuit instead
of choke and starter arrangement
Manish Debnath
(B-tech in Electrical Engineering, NIT, Agartala (Tripura, India 799055)
ABSTRACT
A fluorescent tube light generally starts glowing when a large voltage is applied across its terminals at the time
of starting for a very short period, once it starts glowing then it will be able to continue with normal supply
voltage. Conventionally this needed high voltage, at the time of starting, is provided by the use of choke starter
arrangement.On the other hand, the circuit which converts the dc into ac is called inverter circuit. This paper
will discuss about an inverter circuit which can be used in place of choke starter arrangement. This inverter
circuit develops high voltage at the time of starting and after that its output voltage will come down to the
normal rated voltage level. This inverter circuit arrangement not only make the tube light performance faster but
also economically preferable.
Keywords–Diode, Fluorescent tube light, Heat sink,Inverter, 2N3055 (N-P-N transistor).
I. INTRODUCTION
In conventional choke starter arrangement a fair
amount of energy is wasted in choke and starter
during starting process and the fluctuation of light at
starting period is also a matter of strain to human eye.
This two drawbacks associated with conventional
method may be eliminated by using this inverter
circuit.In developing countries like India load-
shedding is a very common problem. Inverter is a
well-known temporary solution during load shedding.
This circuit can also fulfill the need of inverterduring
load shedding. Simply the same circuit can be used in
place of choke starter arrangement in normal time
and in load-shedding period this circuit can be
energized by battery or other DC source and as a
result we get an AC voltage as output for lighting
tube light, like normal supply condition.The
operation during load-shedding and normal supply
condition is controlled by a relay. The block diagram
of the operating system of inverter circuit is shown
below.
Fig.1 Block diagram of operation of Inverter circuit
II. Conventional starting process of
fluorescent tube light
Fig.2 Conventional starting method of fluorescent
tube light
RESEARCH ARTICLE OPEN ACCESS

In conventional starting method of a fluorescent
tube light, a starter and a choke has been connected in
the tube light circuit. The purpose of these two
accessories is explained as follows.
When AC supply voltage is given to its input
terminals full supply voltage appears across the
starter electrodes P and Q (shown in Fig.2). This
causes discharge in the argon gas with consequent
heating (the electrodes are enclosed in a glass bulb
filled with argon gas). Due to this bimetallic strip
heats up and bends and there by causes contacts P
and Q of the starter to close. When this happens, the
choke, the filament electrodes FF of the tube and
starter becomes connected in series across the supply.
A currents flows through the filament electrode FF
which heated them. Meanwhile, the discharge in the
starter tube disappears and after sometime the
electrodes P and Q move apart. The moving part of
the electrodes P and Q causes a sudden break in the
circuit this cause high value of emf to be induced in
the choke.
The direction of induced emf in the choke will be
such that it will try to oppose the fall of current in the
circuit (according to Lenz’s law). Therefore, the
polarity of the induced emf in the choke will be such
that the voltage appearing across tube terminals will
be equal to the addition of the supply voltage and the
induced emf in the choke. The voltage thus acting
across the electrodes FF is high enough to cause a
discharge occur in the gas inside the tube. Thus the
fluorescent tube starts giving light. Once the
discharge has occurred a much lower voltage (than
the value of the supply voltage at starting)is require
to maintain the discharge. Thereafter, the choke acts
only to reduce the voltage available across the tube.
A capacitor C connected across the starter terminals
to suppress the electromagnetic waves generated at
the gap due to sparking. The whole starting process is
shown graphically as follows.
Fig.3 Graphical representation of Conventional
starting process of fluorescent tube light(with choke
and starter)
From the above it is clear that the necessary
condition to start a fluorescent tube light is that we
have to apply a very high voltage across the filament
electrodes FF at starting to cause a discharge occur in
the gas inside the tube. Once the discharge has
occurred a much lower voltage (than the value of the
supply voltage at starting) is require to maintain the
discharge.
III. WORKING PRINCIPLE OF
INVERTER
An inverter is a device that changes or inverters
direct current (DC) input to alternating current (AC)
output. It doesn't "create" or "make" electricity, just
changes it from one form to another. DC in is
changed to AC out. The input voltage, output voltage
and frequency, and overall power handling depend on
the design of the specific device or circuitry. The
inverter does not produce any power; the power is
provided by the DC source. DC to AC inverters
efficiently transform a DC power source to a high
voltage AC source, similar to power that would be
available at an electrical wall outlet. Inverters [1] are
used for many applications, as in situations where
low voltage DC sources such as batteries, solar
panels or fuel cells must be converted so that devices
can run off of AC power. One example of such a
situation would be converting electrical power from a
car battery to run a laptop, TV or cell-phone.
Here our inverter circuit is working with the
principle of common emitter-biasing of BJT (bipolar
junction transistor). Here one n-p-n power transistor
(2N3055) is used as BJT. The collector terminals of
the transistor is connected with 12V dc and the output
signal of the RC oscillatory circuit is given to the
base terminal of the transistor. According to this base
signal the output is varied and as a result we get an
AC voltage as output.
The working diagram of n-p-n transistor
(2N3055) is shown below.
Fig.4 working diagram of n-p-n transistor (2N3055)
This output voltage is then increased to 230V
(approximately) with the help of a step-up
transformer. During working time n-p-n transistor
(2N3055) is heated up. To control this problem we
set-up N-P-N transistor (2N3055) on a heat-sink (as
shown in Fig.5 and Fig.10).

IV. STARTING OF FLUORESCENT
TUBE LIGHT WITH THE
INVERTER CIRCUIT
Fig.5The whole connection diagram of the inverter
circuit
In the previous para we are discussing the
normal operating function for running the tube light
after starting. But during starting there are certain
things happen which increase the output voltage or
secondary terminal voltage of the step-up transformer
very high (nearly thousand volts) than the normal
rated value of voltage which is about 230 V in this
case. In the circuit diagram it is shown there are four
capacitor of different values are connected. When the
switch of the supply is closed these capacitors are
immediately going to charging mode and a very high
current than normal rated value flow through the
several paths provided to the circuit including
through the coils of the two primary windings of the
step-up transformer. Here the step up transformer has
two primary windings and one secondary
winding.Now we will see how these high currents,
flow through the coils of the two primary windings of
the step-up transformer cause to increase the voltage
of the secondary winding at a very high value for a
very short period (few millisecond) at starting.
Fig.6 Step-up transformer of the inverter circuit
Let, the primary windings voltages are Vp1 and
Vp2, currents are Ip1 and Ip2, inductances are L1and
L2.
For simplicity consider voltage, Vp =Vp1=Vp2;
current, Ip = Ip1 = Ip2 and inductance Lp = L1 = L2.
So, Vp = Lp (dIp/dt)…………. (1)
Let, the starting process is completed during the
time period t0 to t1.
We can rewrite the equation (1) as follows,
Vp = Lp ( Ip/ t) (As we measure
the change from point t0 to t1)
Here the starting process is completed several
times faster than the conventional method.
We can assume t0 = 0 (just at switch on)
and t1= 0+
(just after the switch on)
So, t = (t1- t0) = very very small
At t = t0, let Ip = I0 but at the time of just switch
on there is no current flows through the primary
winding coils of the step-up transformer. Therefore,
the primary winding current is zero. So, I0 = 0.
At t = t1, let Ip = I1; here at t1(just after the switch
on) the current flows through the primary winding
coils (Lp) is very high as the capacitor are
immediately going to charging mode and the
charging currents mainly flow through the two
primary winding coils (Lp1 and Lp2).So, I1 is very
high.
So, Ip = (I1- I0) = I1 - 0 = very high
Here, Ip is very high and t is extremely small.
So, the ratio ( Ip/ t) is very high.
Therefore, primary side voltage,
Vp = Lp ( Ip/ t) is very high.
As the transformer is step-up with transformation
ratio, a = (Vs / Vp) = (230/12) = 19.17 ~ 20 (for
simplicity)
Then the secondary or output voltage of the
inverter circuit, Vs = a Vp ~ 20 * Vp (about twenty
times higher than primary) becomes very high.
So, a very high voltage (nearly thousand volts) is
appeared across the secondary side of the step-up
transformer for a very short duration at the time of
starting which is the most important condition for
startinga tube light. Here in the Fig.6 it is shown that
the two terminals of each filament (F) of the tube
light in both side are short circuited. So, this high
voltage of the secondary side of the step-up
transformer directly appeared between the two
filaments FF shown in the Fig.6. The voltage thus
acting across the electrodes FF is high enough to
cause a discharge occur in the gas inside the tube.
Thus the fluorescent tube starts giving light. After
that the output voltage of the inverter circuit is come
down to its normal rating voltage. Once the discharge
has occurred a much lower voltage (than the value of
the supply voltage at starting) is require to maintain
the discharge.
Now we will see the graphical character of
supply voltage, output voltage both at starting and
running.

Fig.7 AC supply voltage (230V and 50Hz)
Fig.8 output voltage value of the inverter circuit
during starting (voltage level coming down from high
voltage to normal rated voltage)
Fig.9 output voltage of the inverter circuit during
normal running condition (after starting the tube light
the voltage remains nearly 230V, 50Hz)
Here the output voltage waveform in normal
running condition is not exactly sinusoidal this may
not cause any problem during normal running
operation of the tube lightbut it can creates problem
in nearby connected communication devices. This
wave shape can be improved by using proper filter
circuit.
Table: List of the components used in the inverter
circuits
Sl.
no.
Name of the
apparatus
Specification Quantity
1. Step-up
transformer
12V (primary) to
230V(secondary)
1
2. Diode 3
3. Capacitor C1=C2=
16V,1000microf;
C3= 104kf, 100V;
C4= 0.1pf
4
4. Pin-board 1
5. Resistor R1=R2=R3=R4=
150 ohm
4
6. Transistor N-P-N (2N3055) 1
7. Heat sink Aluminum 1
REAL TIME IMAGE OF INVERTER CIRCUIT
Fig.10 Real time image of the inverter circuit
V. CONCLUSION
Here one thing is that at normal supply condition
first the AC (230V and 50Hz) is converted into DC
(12V) by a rectifier circuit then this DC is given to
the inverter circuit for lighting tube light. During,
load-shedding this inverter circuit is energized
directly by battery (12V) or other dc source. Here, the
operation is controlled by a relay which connects the
rectifier circuit to the inverter when the supply is ON
and connects the battery or DC source when supply is
OFF (during load-shedding period). The whole
process is controlled automatically. Where the places
are free from load shedding problems,there the use of
this inverter circuit is not so economicalas the cost of
the inverter circuit is just slightly less than
conventional choke-starter arrangement but one can
also get a faster operation experience with this
circuit. The working life of this inverter circuit is
more than conventional choke-starter arrangement
and during running condition the losses are slightly
less thantheconventional choke-starter arrangement.
The circuit construction is very complex than
conventional choke-starter arrangement but this is the
matter of concern for the manufacturers. On the other
hand, conventional choke-starter arrangement
connection with the tube is complicated, one cannot
easily make the connection without prior knowledge
but on can easily connect the tube with the output

terminals of this inverter circuit. The real benefits of
this circuit can be gotten when we use it in areas
associated with load-shedding problems. Here no
need to install double arrangements one for normal
supply and other for the load-shedding period, the
single circuit can performs the same task smoothly in
both the conditions and the result is that installation
cost come down about half of the conventional
method. The main drawback of this circuit is that the
output voltage waveform in normal running condition
is not uniform or exactly sinusoidal and sometimes it
may produce spike in output voltage wave, this may
not cause any problem during normal running
operation of the tube light butit can creates problem
in nearby connected communication devices. This
thing can be improved by using proper filter circuit.
REFERRENCES
[1] Eskom’s, “Renewable energy experience”
presented at village power 98, Oct 6-8,
1998.
[2] Yi Huang; Miaosen Shen; Peng, F.Z.; Jin
Wang; “Z-Source Inverter for Residential
Photovoltaic Systems”, IEEE Transactions
on Power Electronics, Volume 21, Issue 6,
pp. 1776 – 1782, Nov. 2006.
[3] M. N. Abdul Kadir and S. Mekhilef “Novel
vector controlmethod for three-stage
hybridcascaded multilevel inverter” IEEE
2011, Trans. Ind.Electron., vol. 58.
[4] L. A. Córdova, L. Empringham, P. Lezana
and C. A. Silva“Implementation and control
of a hybrid multilevel converter withfloating
dc links for current waveform improvement”
IEEE Trans. Ind.Electron., 2011 vol. 58,no.
[5] K. Jang-Hwan, S.-K. Sul, and P. N. Enjeti,
“A carrier-based PWM method with optimal
switching sequence for a multilevel four-leg
voltage source inverters”,IEEE Trans. Ind.
Appl., vol. 44, no. 4, pp. 1239–1248 ,
Jul./Aug. 2008.
Author’s Biography
Manish Debnath, received B-tech
degree in Electrical Engineering
from NIT, Agartala in the year
2014 (Enrollment no. 10UEE035).
His research interest includes
Power System, Power electronics
and Control System.
Email : debnathmanish123@gmail.com

Starting of fluorescent tube light by using inverter circuit instead of choke and starter arrangement

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