(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) = (Power consumption)
(Efficiency)
Efficiencies of some electrical appliances are as follows:
Single-phase motor - a * . . e . - * . * * . . * . - 0.6 - 0.75
The smaller the motor, the
Three-phase motor * * a . - . * * * - * . . * * * 0.65 - 0.9
It-
lower the efficiency.
Fluorescent lamp - * * . * * . * * * . * * . . - . * * 0.7 - 0.8
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 57W by 1.2
- 2 and you will get the figure of the necessary
capacity of a generator. In other words, a generator with a rated output of 1OOOWcapacity
can light nine to fourteen 40W fluorescent lamps.
Example 2:
Generally speaking, a 400W motor means that its work load is 400W. Efficiency of this
motor is 0.7 and power consumption will be 400 + 0.7= 57OW. When this motor is used for
a motor-driven tool, the capacity of the generator should be multiplied by 1.2 to 3 and 570W
as explained in the
item(3).
Electrical appliance
Applicable limit
50Hz 60Hz
lncandesent lamp, heater, etc.
Fluorescent lamp, mercury lamp, etc.
approx.800W
I
approx.1 OOOW
approx. SOW
I
approx. 650W
Motor-driven tool, general-purpose motor, etc.
Water pump, compressor, etc.
approx. 500W
approx. 250W ’
approx. 600W
approx. 300W
Table 7-1
NOTES: Wiring between generator and electrical appliances
1.
Allowable current of cab/e
2.
Use a cable with an allowable current that is larger than the rated input current of the load
(electrical appliance). If the input current is larger than the allowable current of the cable used, the
cable will become excessively heated and deteriorate the insulation, possibly burning it out.
Table 7-2 shows cables and their allowable currents for your reference.
Cable length
If
a
long cab/e is used, a voltage drop occurs due to the increased resistance in the conductors
decreasing the input voltage to the load (electrical appliance). As a result, the load can be
damaged.
Table 7-2 shows voltage drops per 100 meters of cab/e.
- 14-
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