LG LMC1575ST Service Manual

5-3
MEASUREMENT OF MICROWAVE POWER OUTPUT
The formula to calculate energy efficient is IEC method.
• Necessary equipment
1. Thermo-hygrometer (T
0
)
2. Electronic scale (m
c
, m
w
)
3. Digital thermometer (T
1
, T
2
)
4.
cylindrical container of borosilicate glass (min. thickness 3 mm * external diameter
190 mm* Height 90)
5. Stopwatch (T : Total time)
6. Digital Power Meter (Energy Consumption, Wh)
7. Oscilloscope, High Voltage Probe (Magnetron Filament heating-up time)
8. Insulation Glove (to move container)
•Test method
1) The MWO & A cylindrical container are at ambient temperature for at least 6 hr.
(T
0
should be 20 ± 1℃ )
2) The ambient temperature (T
0
) of room must be recorded by Thermo-
hygrometer.
3) The weight of empty cylindrical container #1 should be measured by Electronic
scale. . (m
c
, Unit: g)
4) A quantity over 1000g (Drinking water, initial temp. 8℃ ↓) is added to the
cylindrical container #2. The water temperature (T
1
) is measured immediately
when the water initial temperature (T
1
) is reached at 10 °C ± 0.2. And then, the
water (1000 ± 5 g) is poured into the cylindrical container #1 and its actual mass
obtained. (mw, Unit: g). The container is then immediately placed in the center
of the oven. Total time (T) is set.
5) Total time(T) can be obtained by repeat testing in other to raise the water
temperature, 10° C ± 0.2℃
For the measurement of the heating-up time of the magnetron filament can be
used in conjunction with an oscilloscope.
t is heating time, excluding the magnetron filament heating-up time. The MWO is
operated. Stop watch is used to count total time. And Energy consumption(Wh)
should be measured from start of operation until T2 is reached. (The MWO is
supplied at rated voltage ± 1 %)
6) The MWO is then switched off and the final water temperature(T
2
) is measured
within 60s. (Note: The water is stirred before its temperature is measured.)
MW power output (unit: W)
P = {4.187 x m
w
x (T
2
-T
1
) + 0.55 x m
c
x (T
2
-T
0
)} / t
Energy efficiency
η = (P x t) / (W x T) x 100
t : T(s) – MGT Filament heating-up time
W = Energy consumption(Wh) x 3600s / T
WATER LOAD
TURNTABLE
BOWL
Simple test method.
• Use this method if testing IEC method is impossible.
For exact result, use IEC method.
This method is for olny this model.
Test condition is different model by model.
1. Check max. power consumption of Micro wave mode.If it is not 1570W±80W,
Check that the inverter is problem.
2. Contain 1000CC. 10℃ water in cylindrical container.
3. Put the water in the microwave ovne and operate it for 45 seconds with max
power.
4. After operation,measure water temperature.
5. The water temperature should have a minimum temperature of 18℃.

LG LMC1575ST Specifications

General

Style	counter top
Color	stainless steel
Total Capacity	1.5 cu. ft.
Convection	no
Power Levels	10
Sensor Cooking	yes
Quick Start	no
Timer	yes
Interior Light	yes
Microwave Power	1, 250 watts
Voltage	120 volts
Current	15a

Weight and Dimensions

Depth	17 inch
Height	12 13/100 inch
Width	21 41/100 inch