Armature Open Circuit Test; Armature And Field Grounded Circuit Test - Ford VSG-411 Service Manual

05-6 Startina Svstem
05-6
TESTING (Continued)
Armature Open Circuit Test
An open circuit armature may sometimes be detected by
examining the commutator for evidence of burning. A spot
burned on the commutator is caused by an arc formed
every time the commutator segment, connected to the
open circuit winding, passes under a brush.
Armature and Field Grounded Circuit Test
The test will determine if the winding insulation has failed,
permitting a conductor to touch the frame or armature core.
To determine if the armature windings are grounded, make
the connection as shown. If the voltmeter indicates any
voltage, the windings are grounded.
Grounded field windings can be detected by first
disconnecting the grounded end of the winding where it
terminates at the frame, then making the connections as
shown. If the voltmeter indicates any voltage, the field
windings are grounded.
ARMATURE GROUNDED CIRCUIT TEST
TESTER k
FIELD GROUNDED CIRCUIT TEST