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7. POWER TOOLS AND AMALL
APPLIANCES
This test would also apply to other similar equipment that has
a line cord. For double insulated power tools, the
megohmmeter lead shown connected to the housing would
be connected to some metal part lf the tool(e..g chuck,blade).
Note:The switch of the device must be in the “ON”position
and the main power should be disconnected.
MOTORS
AC-Disconnect the motor from the line by disconnecting the
wires at the motor terminals or by opening the main switch.
If the main switch is used and the motor also has a starter
then the starter must be held, by some means, in the “ON”
position. In the latter case, the measured resistance will
include the resistance of the motor, wire and all other
components between the motor and the main switch. If a
weakness is in dicated, the motor and other components
should be checked individually. If the motor is disconnected
at the motor terminals, connect one megohmmeter lead to
the grounded motor housing and the other lead to One of the
motor leads. DC-Disconnect the motor from the line. To test
the brush rigging,field coils and armature connect one
megohmmeter lead to the grounded motor housing and the
other lead to the brush on the commutator. If the resistance
measurement indicates a weakness,raise the brushes off the
commutator and separately test the armature, field coils and
brush rigging by connecting one megohmmeter lead to each
of them individually, leaving the other connected to the
grounded motor housing. The above also applies to DC
Gemerators.
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