EXTECH EX380363 [8/10] Testing cables

Model 380363-EU-EN-V-3.1-1/12

Testing DC Motors

1. Disconnect the motor from the line.

2. To test the brush rigging, field coils and armature, connect one meter lead to the grounded

motor housing and the other 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 (one at a time). Leave one lead

connected to the grounded motor housing while testing the motor components. This also

applies to DC Generators.

Testing Cables

1. Disconnect the cable under test from the line.

2. Disconnect the opposite end of the cable to avoid errors as a result of leakage from other

equipment.

3. Check each conductor to ground and/or lead sheath by connecting one meter lead to ground

and/or lead sheath and the other meter lead to each of the conductors in turn.

4. Check insulation resistance between conductors by connecting meter leads to conductors in

pairs. Refer to diagram. In the diagram, note that the 3-conductor cable has two wires shorted

to the ground shield. This two-wire/shield connection is then connected to one side of the

meter. The remaining conductor is connected to the other side of the meter.