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5-8 Output Power of Magnetron
The output power of the magnetron can be measured by performing a water temperature rise test.
Equipment needed :
* Two 1-liter cylindrical borosilicate glass vessel (Outside diameter 190 mm)
* One glass thermometer with mercury column
NOTE: Check line voltage under load. Low voltage will lower the magnetron output. Make all temperature
and time tests with accurate equipment.
1. Fill the one liter glass vessel with water.
2. Stir water in glass vessel with thermometer, and record glass vessel's temperature ("T1", 10±1°C).
3. After moving the water into another glass vessel, place it in the center of the cooking tray. Set the oven to
high power and operate for 55seconds exactly. (3 seconds included as a holding time of magnetron
oscillation:)
4. When heating is finished, stir the water again with the thermometer and measure the temperature ("T2").
5. Subtract T1 from T2. This will give you the water temperature rise. (
△
T)
6. The output power is obtained by the following formula;
Output Power =
4.187 x 1000 x
△
T+0.55xMcx(T
2
-T
0
)
55 : Heating Time (sec)
52
52 : Counting Time (sec)
4.187 : Coefficient for Water
1000 : Water (cc)
△
T : Temperature Rise (T1-T2)
To : Room Temperature
Mc : Cylindrical borosilicate glass weight
7. Normal temperature rise for this model is 9°C to 11°C at 'HIGH'.
NOTE 1: Variations or errors in the test procedure will cause a variance in the temperature rise.
Additional power test should be made if temperature rise is marginal.
NOTE 2: Output power in watts is computed by multiplying the temperature rise (step 5) by a factor of 91
times the of centigrade temperature.
5-9 Microwave Heat Distribution - Heat Evenness
The microwave heat distribution can be checked indirectly by measuring the water temperature rise at
certain positions in the oven:
1. Prepare five beakers made of 'Pyrex', having 100 milliliters capacity each.
2. Measure exactly 100milliliters off water load with a measuring cylinder, and pour into each beaker.
3. Measure the temperature of each water load. (Readings shall be taken to the first place of decimals.)
4. Put each beaker in place on the cooking tray as illustrated in figure below. Start heating.
5. After heating for 2 minutes, measure the water temperature in each beaker.
6. Microwave heat distribution rate can be calculated as follows:
Minimum
Heat Distribution =
Temperature Rise
X 100(%)
Maximum
Temperature Rise
The result should exceed 65%.
CAUTION
MICROWAVE RADIATION
PERSONNEL SHOULD NOT ALLOW EXPOSURE TO MICROWAVE RADIATION FROM MICROWAVE
GENERATOR OR OTHER PARTS CONDUCTING MICROWAVE ENERGY.
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