Extech Instruments MG500 User Manual page 11

DC Motor Test
1. Disconnect the motor from the line.
2. To test the brush rigging, field coils, and armature, connect the RED lead to the grounded
motor housing and the GREEN lead to the brush on the commutator.
3. If the resistance measurement indicates a weakness, raise the brushes off of the
commutator and separately test the armature, field coils, and brush rigging by connecting
one lead to each individually, leaving the other connected to the grounded motor housing.
This also applies to DC Generators.
Testing Single Conductor Cables
1. Completely disconnect the cable
under test from its source and
destination.
2. Connect the test leads to the
cable as shown at right.
Testing Multi Conductor Cables
1. Completely disconnect the cable under test from its source and destination.
2. Refer to the diagrams below for three possible tests.
EARTH
LINE
Testing one conductor to
all of the conductors
Shop for Extech products at:
Core
EARTH
EARTH
LINE
GUARD
Testing one conductor
to earth
11
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Insulation Sheath Covering
GUARD LINE
GUARD
LINE
EARTH
One conductor to all
minus ground
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