DC Motors
15
4.
When contact is made, the needle will first deflect in either the up scale
or down scale direction and then return to zero. Deflection will be in the
opposite direction when contact is broken.
5.
Relative polarities of the shunt and series fields are correct
(ampere-turns are cumulative) if the voltmeter needle deflects up scale
when contact is made and down scale when contact is broken.
6.
Relative polarities of the shunt and series fields are incorrect
(ampere-turns are differential) if the voltmeter needle deflects down
scale when contact is made and up scale when contact is broken. The
motor connections must be changed so that relative polarity is correct.
Relative polarity can be incorrect because of an error in the connections to
the control or because the series fields leads are improperly marked. In any
case, the motor connections must be changed so that relative polarity is
correct.
If only one series field terminal is available at the controller, use it and the
available armature terminal for the test. For example, use S-2 and A-l, if S-1
and A-2 arc connected together at the motor and not brought to the
controller.
Maintenance
Inspections
Regular inspection at intervals dependent upon service conditions is the best
insurance against costly maintenance and breakdown. Experience is the best
guide. Record inspection results and maintenance action required or
performed.
Cleanliness
Keep the interior parts of machines clean and dry. Remove dust, dirt,
corrosion, grease, oil and moisture. If used, ventilating air filters must be
kept clean or replaced to assure full volume of cooling air.
Lubrication - Frames DC180ATZ & DC210ATZ
DC180ATZ frame has oversize grease reservoirs to provide lifetime
operation in normal industrial applications. Where severe duty conditions
require regreasing, the following procedures should be followed:
!
ATTENTION:
Internal parts of this motor may be at line
potential even when it is not rotating. Before performing any
maintenance which could result in contacting any internal part, be
sure to disconnect all power from the motor. Failure to observe
this precaution could result in severe personal injury or death.
