Amprobe AMB-35 Insulation-Tester - Manual (Page 7)

11
9. POWER TOOLS AND SMALL APPLIANCES
This test would also apply to other similar equipment that has a power
cord. For double insulated power tools, one lead of the megohmmeter
must be connected to the housing. The other leads would be connected
to some metal part of the tool (e.g. chuck, housing bolt).
Note: The power switch must be in the “ON” position and the main power
should be disconnected.
MOTORS
Disconnect the motor from the line by disconnecting the wires at the
motor terminals or by opening the main switch. If a main switch is used
and the motor has a starter contactor then the starter contacts must be
held closed by some means, possible by energizing the coil. 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 problem is indicated, 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
hot motor lead.
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 problem, 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 Generators.
12
CABLES
Disconnect the cable from power. Also, disconnect the opposite end of the
cable to avoid any leakage due to the load. Check each conductor to
ground and/or lead source by connecting one megohmmeter lead to ground
and/or lead source and the other megohmmeter lead to each of the
conductors. Check insulation resistance between conductors by connecting
megohmmeter leads to conductors in pairs.
10. FUSE CHECK & REPLACEMENT
10-1 Testing the Fuse
1). Set the function switch to LoΩ position.
2). Connect the test leads to the input terminals and short then together.