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8'
(5)
Appliances without any indication as to
power
consumption
Some appliances have no indication as to power consumption; but instead the work load (output) is
indicated. In such a .case, power consumption is to
be
worked out according to the numerical formula
mentioned below.
(Output of electrical appliance)
(Efficiency)
=
(Power consumpition)
Eff iciencies.of some electrical appliances are as follows
:
Single-phase motor
................................
0.6
t0
0.75
The smaller the motor, the
Fluorescent lamp
...................................
0.7
to
0.8
(
lower the efficiedCY.
Example
1:
A
40W fluorescent lamp means that its luminous output is
40W.
Its efficiency is
0.7
and
accordingly, power consumption will be 40
+
0.7=
57W.
As
explained in Item
(2),
multiply
this power consumption value of
57
W by 1.2 to 2 and you will get the figure of the neces-
sary capacity of a generator. In other words, a generator with a rated output of 1 OOOW
capacity can light nine to fourteen
40
W fluorescent lamps.
Example
2
:
Generally speaking, a
400
W motor means that its work load is 400
W.
Efficiency of this
motor is
0.7
and power consumption
will
be 400+0.7=
570
W. When this motor is used for
a motor-driven tool, the capacity ofthe generator should be multiple of
570
W
by 1.2
to
3
as
explained in the Item
(3).
570
(W)
x
1.2 to
3
=
684
(W) to
1710
(W)
I
Frequency
I I
60
Hz
I
lncandesent lamp, heater, etc.
6000
W
Fluorescent lamp, Motordriven tool,
general-potpose
approx.
3000
W
Mercury lamp, etc. approx.
2000
W
Pump, compressor, etc.
approx.
1400
W
Table.
7-1
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21
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