– 42 –
PROCEDURE FOR MEASURING
MICROWAVE ENERGY LEAKAGE
CAUTIONS
• Be sure to check a microwave emission prior to
servicing the oven if the oven is operative prior to
servicing.
•
The service personnel should inform the
manufacturer, importer, or assembler of any certified
oven unit found to have a microwave emission level
in excess of 4 mW/cm
2
and should repair any unit
found to have excessive emission levels at no cost
to the owner and should ascertain the cause of the
excessive leakage. The service personnel should
instruct the owner not to use the unit until the oven
has been brought into compliance.
• If the oven operates with door open, the service
personnel should;
— Tell the user not to operate the oven.
— Contact the manufacturer and CDRH (Center for
Devices and Radiological Health) immediately.
NOTE:
Address on CDRH:
Office of Compliance (HFZ-312)
Center for Devices and Radiological Health
1390, Piccard Drive,
Rockville, Maryland 20850
• The service personnel should check all surface and
vent openings for microwave emission testing.
• Check for microwave energy leakage after every
servicing. The power density of the microwave
radiation leakage emitted by the microwave oven
should not exceed 2 mW/cm
2
.sq.
And always start measuring of an unknown field to
assure safety for operating personnel from radiation
leakage.
NOTE:
The standard is 4 mW/cm
2
.sq. while in the
customer’s home. 2 mW/cm
2
.sq. stated here is
manufacturer’s own voluntary standard for units in
customer’s home.
EQUIPMENT
• Electromagnetic energy leakage monitor (NARDA
8100B, HOLADAY HI-1501)
• 600 cc glass beaker
• Glass thermometer 100°C or 212°F
MEASURING MICROWAVE ENERGY
LEAKAGE
• POUR 275 ± 15cc of 20 ± 5°C, 68 ± 9°F water in a
beaker which is graduated to 600 cc, and place the
beaker in the center of the oven.
• Set the energy leakage monitor to 2,450 MHz and
use it following the manufacturer's recommended
test procedure to assure correct result.
• When measuring the leakage, always use the 2 inch
(5cm) spacer supplied with the probe.
• Operate the oven at its maximum output.
• Measure the microwave radiation using an
electromagnetic radiation monitor by holding the
probe perpendicular to the surface being measured.
Move probe along shaded area
Probe scanning speed
Less than 2.0 cm/sec
MEASUREMENT WITH THE OUTER
CASE REMOVED
• When you replace the magnetron, measure
microwave energy leakage before the outer case is
installed and after all necessary components are
replaced or adjusted.
Special care should be taken in measuring the
following parts.
— Around the magnetron
— The waveguide
Fig. 42
Fig. 43
WARNING :
AVOID CONTACTING ANY HIGH
VOLTAGE PARTS
