P Nominal
lamp power t Average
lamp life time( appr. 5
yrs) t Average
daily operation time(10 -
24hrs) t Average
operation time for a
year b Power
control coefficient (see Fig.1/A,
[1], and
[2]) a Dimming
coefficient (see
Fig.1/B) D Dimming
duty cycle (see
Fig.1/B) h Efficiency
of
ballast(P The energy
consumption for a year can be calculated
as follows: where W The quantity
(P Let consider two
different ballasts B1 and B2.
Therefore where W Assuming
W gives the yearly
saved energy if ballast B1 is substituted
with ballast B2. The energy saving
factor can be defined as
follows Therefore the energy
saving factor gives the yearly saved
energy as the percentage of the yearly
ideal energy consumption if the ballast B1
is substituted with ballast B2 where
W If no dimming
applied the expression for the energy
saving factor simplified to Fig, 3 shows a
diagram for the energy saving factor,
parameterized by b In this case no
dimming applied for ballast B1,
therefore Fig. 4 shows a
diagram for the energy saving factor,
parameterized by the efficiency of ballast
B1, where a The price of a high
efficient electronic ballast can be
essentially higher than a conventional
core & coil one. Therefore it is
important to know in advance the price
compensation time provided by the energy
saving of the more expensive electronic
ballast. C Price of
the ballast B1(conventional core
& coil) C Price of
the ballast
B2(electronic) q Cost of
energy[$/kWh] P Nominal
lamp power F Energy
saving factor W Average
yearly saved energy The
formula for compensation time can be
written as where
C P h b B1 0.82 1.05 B2 0.95 1.0 Energy and cost
savings are summarized in the following
table if the conventional core & coil
ballasts (CWA, efficiency: 80%(100W),
83%(250W) and 87%(400W) are substituted
with high efficient, for instance
Ballastronic's (95%) electronic ballasts.
Compensation time can be expected from one
to two years. This time can be essentially
less if dimming is applied. [1]
Unglert,M.C., [2]
Melis,J., Copyright
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