ALL-TEST
PRO
®
31 User Manual
©2011, ALL-TEST
Pro,
LLC
www.alltestpro.com
rev 2011-11F
33
Testing an Assembled DC Motor
Connect the ALL-TEST
PRO®
31’s ground lead (yellow lead) to an earth ground at the test point.
Series DC motor
DC series motors provide a special problem since the series field is constructed of a few turns of very
large wire to handle the high current through the armature and field. This combination provides a very
low impedance value. The best method of testing this type of motor is by trending, looking for changes,
particularly I/F and phase angle (Fi).
Testing Series Field
1.
Connect the instrument test leads to motor series field leads S1 & S2.
2.
Select the Motor Test from the main menu
(see Winding Test section)
.
3.
Adjust the test frequency to get the impedance value above 1 Ohm and below 999 Ohms.
4.
Record the test frequency, impedance and phase angle readings.
5.
Compare these results to series field readings from a similar motor or to a baseline reading on the
same motor and note any changes.
Testing the Armature Field
See the
Armature Testing
section below.
For Interpretation:
See the
DC Motor Analysis
section on page 34
Compound or Shunt DC motor
Testing Shunt Field
1.
Connect the instrument test leads to shunt field connectors F1 & F2.
2.
Select the Motor Test from the main menu
(see Winding Test section)
.
3.
Adjust the test frequency to get the impedance value above 1 Ohm and below 999 Ohms.
4.
Record the test frequency, impedance and phase angle readings.
5.
Compare these results to readings from a similar motor or to a baseline reading on the same
motor and note any changes.
Testing the Armature Field
See the
Armature Testing
section below.
Armature Testing
DC armatures are time consuming but relatively easy to test. There are three basic methods of testing
DC armatures.
·
Trending
·
Assembled
·
Disassembled
