(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 electkd amfiance) = (Power consumption)
(Efficiency)
Efficiencies of some electrical appliances are as follows:
Single-phase motor . . . . . . . . . . . . . . . 0.6 - 0.75
Three-phase motor . . . . . . . . . . . . . . . 0.65 - 0.9
t
The smaller the motor, the 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 ac-
cordingly, 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 500W capacity
can light four to seven 40W fluorescent lamps.
Example 2:
Generally speaking, a 400W motor means that its work load is 400W. Efficiency of this mo-
tor is 0.7 and power consumption will be 400 t 0.7 = 570W. When this motor is used for a
motor-driven tool, the capacity of the generator should be multipled by 1.2 to 3 and 570W
as explained in the
Item 3.
ELECTRIC DEVICES
Incandescent lamp, electric heater, etc.
Fluorescent lamp, mercury lamp, etc.
RANGE OF APPLICABLE LOADS
50 Hz
60 Hz
up to 450w
up to 550w
Up to approx. 350W
Up to approx. 450W
Motor-driven tools etc. Up to approx. 350W
Up to approx. 400W
I
Pump and compressor drive motors
Up to approx. 15OW
Up to approx. 18OW
Table 7- 7
NOTES: Wiring between generator and electrical appliances
1. Allowable current of cable
Use a cable with an allowable current that is higher than the rated input current of the load (elec-
trical appliance). If the input current is higher than the allowable current of the cable used, the
cable will become excessively heated and deteriorate the insulation, possibly buring it out.
Table 7- 2 she ws cables and their allowable current for your reference.
2. Cable length
If a long cable is used, a voltage drop occurs due to the increased resistance in the conductors so
that the input voltage to the load (electrical product) decreases. As a result, the load can be dam-
aged.
Trable 7-2 shows voltage drops per 100 meters of cable.
- 17-
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