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(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 O O O W
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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