Safety Inspection And Tests After Repair And Maintenance In The Primary Circuit - Fluke PM3082 Service Manual

SAFETY INSPECTION AND TESTS
9 SAFETY INSPECTION AND TESTS AFTER REPAIR
AND MAINTENANCE IN THE PRIMARY CIRCUIT
9.1 GENERAL DIRECTIONS
- Take care that the creepage distances and clearances have not been reduced.
- Before soldering, bend the wires through the holes of the solder leads, or wrap the wires around
the leads in the form of an open U, or, maintain wiring ridigity by cable clamps or cable lacing.
- Replace all insulating guards and plates after performing all repairs.
9.2 SAFETY COMPONENTS
For safety reasons, components in the primary circuit may only be replaced by components indicated
in the replaceable parts list.
9.3 CHECKING PROTECTIVE GROUND
The correct connection and condition is checkeidby visual control and by measuring the resistance
between the protective ground connection at the plug and the cabinet/frame. The resistance shall not
be more than 0.5 £2, test current 25A. During measurement the line cable should be removed from
line power. Resistance variations indicate a defect.
9.4 CHECKING INSULATION RESISTANCE
Measure the insulation resistance at U = 500 V dc between the line connections and the protective
ground connections. For this purpose, set the mains switch to ON. The insulation resistance shall not
be less than 2 M£1
NOTE: The insulation resistance of 2 M il is a minimum requirement at 40 °C and 95% relative
humidity. Under normal conditions the insulation resistance should be much higher
(10... 2 0 M il).
9.5 CHECKING LEAKAGE CURRENT
The leakage current shall be measured between each pole of the line power supply in turn, and all
accessible conductive parts connected together {including the measuring ground terminal).
The leakage current is not excessive if the measured currents from the mentioned parts is <, 0.5 mA
rms (without filter capacitor) or 2 3.5 mA rms (with filter capacitor).
9.6 VOLTAGE TEST
The instrument shall withstand, without electrical breakdown, the application of a test voltage
between the supply circuit and accessible conductive parts that are likely to become energized. The
test potential shall be 1500 V rms or dc equivalent at supply-circuit frequency, applied for one second.
The test shall be conducted when the instrument is fully assembled, and with the primary switch in
the ON position.
During the test, both sides of the primary circuitJOf the instrument are connected together and to one
terminal of the voltage test equipment; the other voltage test equipment terminal is connected to the
accessible conductive parts.
9- 1