LG LMV1762SB, Service Manual

Page: 26 / 48

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8. POWER OUTPUT MEASUREMENT
(1) Microwave power output measurement is made
with the microwave oven supplied at its rated voltage
and operated at its maximum microwave power setting
with a load of (1000 ± 5) g of potable water.
(2) The water is contained in a cylindrical borosilicate
glass vessel having a maximum material thickness
of
1
/
8
” (3 mm) and an outside diameter of approximately
7.6” (190mm).
(3) The oven and the empty vessel are at ambient
Temperature (T0) prior to the start of the test.
(4) The initial temperature (T1) of the water is
(10 ± 1) °C (50°F) It is measured immediately before the
water is added to the vessel. After addition of the water
to the vessel, the load is immediately placed on the
center of the turntable which is in the lowest position
and the microwave power is then switched on.
(5) The time t for the temperature of the water to rise
by a value T of (10 ± 1) °K is measured, where t is the
time in seconds and T is the temperature rise.
The initial and final water temperatures are selected so
that the maximum difference between the final water
temperature and the ambient temperature is 5°K.
(6) The microwave power output P in watts is calculated
from the following formula:
4.187 Mw(T2 –T1)+0.55Mc(T2 –T0)
t
is measured while the microwave generator is
operating at full power. Magnetron filament heat-up
time is not included. (about 3 seconds)
(7) The water is stirred to equalize temperature
throughout the vessel, prior to measuring the final
water temperature.
(8) Stirring devices and measuring instruments are
selected in order to minimize addition or removal of
heat.
P =
Where
P is the microwave power output, in watts
Mw is the mass of the water, in grams
Mc is the mass of the container, in grams
T0 is the ambient temperature, in °C
T1 is the initial temperature of the water, in °C
T2 is the final temperature of the water, in °C
t is the heating time in seconds, excluding the magnetron filament heat-up time.
WATER LOAD
TURNTABLE