Sharp R-3H57 Service Manual page 12

R-3H57
PROCEDURE
LETTER
6. Measure the final water temperature. (Example: The final temperature T2 = 21 C)
7. Calculate the microwave power output P in watts from above formula.
Initial temperature .................................................................................................. T1 = 11 C
Temperature after (47 + 2) = 49 sec. ..................................................................... T2 = 21 C
Temperature difference Cold-Warm ....................................................................
Measured output power
The equation is "P = 90 x T" ....................................................... P = 90 x 10 C = 900 Watts
JUDGMENT: The measured output power should be at least
CAUTION: 1 C CORRESPONDS TO 90 WATTS REPEAT MEASUREMENT IF THE POWER IS
MICROWAVE OUTPUT POWER (2 Litre water load)
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (with outer case fitted).
Microwave output power from the magnetron can be measured by way of substitution, i.e. it can be
measured by using a water load how much it can be absorbed by the water load. To measure the
microwave output power in the microwave oven, the relation of calorie and watt is used.
On the other hand, if the temperature of the water with V(ml) rises T (˚C) during this microwave heating
period, the calorie of the water is V x T.
The formula is as follows;
P = 8330 x
Our condition for water load is as follows:
Room temperature ................. 23 2˚C
Water load ...... 2000 ml
P = 75 x T
Measuring method:
A) The two water containers must be prepared.
The water container must be one (1) litre beaker made of Pyrex glass and its diameter approximately
12cm.
B) Put the one (1) litre water into each beaker (Each beaker has one litre water). The initial temperature
of the water should be 23 1˚C.
C) Mark T1 on the one beaker and mark T2 on the other one. And stir the water and measure the
temperature of water the thermometer and note them. The graduation of the thermometer must be
scaled by 0.1˚C at minimum and an accurate mercury thermometer is recommended.
D) Place the two (2) beakers as touching each other in the centre of the oven cavity.
E) Set the timer to 1 minutes and 51 seconds, start the oven at 100% power.
F) The time must be measured with stopwatch or wristwatch.
G) After 1 minutes and 51 seconds, stop the oven by opening the door.
H) Put the two (2) beakers out of the oven cavity and measure the temperature of the water by stirring
the water with thermometer and note them.
TEST PROCEDURES
INSUFFICIENT.
1000g
1000g
T1˚C
T/t
Initial temperature ...... 23 1˚C
COMPONENT TEST
Heat up for49 sec.
Power supply Voltage ............. Rated voltage
10
T1 = 10 C
15 % of the rated output power.
1000g
T2˚C
Heating time ...... 1 min. 51sec.