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MOTOR SERVICE PROCEDURE
Any competent motor shop that can overhaul AC induction motors
may service Brushless DC motors. There are differences that
must be observed in the permanent magnet rotor, the feedback,
and the bearings.
PERMANENT MAGNET ROTOR
the Brushless DC motor are constructed of a highly stable
material and will not demagnetize under normal conditions. The
motors can be disassembled and reassembled without affecting
the strength of the magnets.
HANDLE THE ROTOR WITH GREAT CARE SINCE THE
MAGNETS ARE BRITTLE AND CAN BE DAMAGED IF
DROPPED! DO NOT SET ON A STEEL SURFACE!
RESOLVER
- The resolver consists of two parts: a rotor
mounted on the shaft and the stator attached to the motor's end
bell at the non-drive end. These components must line up
properly if the motor is to operate correctly. See page 8 for the
encoder alignment procedure after re-assembling an encoder
equipped motor.
BEARINGS
-- Bearings are press-fit on the rotor shaft. The rear
(non-drive end) bearing is fixed in place by a bearing retainer
plate, and both bearings are slip fit into their housings. When
replacing bearings, they must be positioned up against the
bearing shoulder on the shaft.
DIS-ASSEMBLY OF THE MOTOR
Refer to exploded view drawing and parts list on page 4. This is
a general drawing, and not all details are shown.
1.
Before disassembling the motor, remove the rear cover
(#19) from the bracket (# 14) to expose the resolver.
2.
Make sure that there are marks on the end bells (#14
and #22), frame (#25), resolver assembly (#15), resolver rotor
(#17), and motor shaft (#2) to locate parts when the motor is
reassembled. Be sure those marks will not be obscured in the
process.
3.
Remove the resolver rotor (#17) from the shaft. It is
secured by two set screws (#16) 90° apart on the hub.
4.
Remove the two bearing retainer plate screws (#13) in
the non-drive end. In some cases this may require loosening the
two set screws (#18) holding the resolver assembly (#15) and
moving the resolver stator out of the way. This releases rear
bearing (#4) and allows removal of the shaft or end bell.
5. Remove four bolts (#11) that hold the drive end bracket
(#22) on. Some motors have hex nuts on overbolts that run the
length of the motor. Note the location of the lifting lugs (#21).
6.
Carefully slide the drive end bracket (#22) off of the
shaft (#2). Don't allow the end bell to scrape the shaft as it is
removed. Note carefully the location of parts that come loose as
the end bell is removed, such as the wave washer (#23) in the
front housing. The rotor stays in the frame assembly.
7.
The rotor (#2) may now be removed by sliding it
POW ERTEC "F" Series Motor Manual
- Permanent magnets used in
slowly out. The banding will protect the magnets against damage
while sliding out straight. Avoid jerky side to side movements.
While the rotor is out of the motor, protect the banding and
magnets from sharp blows and pointed objects.
8.
If only the rotor assembly is to be serviced, it is not
necessary to remove the resolver end bracket (#14). If the motor
stator is to be rewound, then the resolver end bracket should be
removed. Remove the two set screws (#18) holding the resolver
(#15) in place. Before removing the resolver, disconnect the
wires from the block (#31) in the motor junction box and tie a
string onto the wires. This will help cable reinstallation. Remove
the assembly.
DO NOT PULL ON THE WIRES OF THE CABLE OR ON
THE ASSEMBLY. Pull the outside cable jacket only.
RE-ASSEMBLY OF THE MOTOR
1.
Make sure the inside surface of the stator is smooth with
no foreign material (such as metal shavings) in the area. Also
check rotor assembly for foreign matter (like metals).
2.
Carefully slide the rotor (#2) into the stator assembly
(#25) slowly,
BEING VERY CAREFUL TO AVOID INJURY TO
THE HANDS OR
ARMS. Make sure you insert the rotor from the
drive end of the frame.
3.
Once the rotor is inside the stator assembly, the
resolver end bracket (# 14) may be installed. Make sure the
marks made before disassembly line up properly. Use long
screws to position the bearing retainer plate before pushing end
bell in. Replace bearing retainer plate screws (#13).
4.
Position the air baffle (#24 - not TENV motors), and
place the wave washer (#23) in position in the front housing.
Replace drive end bracket (#22) according to the marks made
before disassembly, being careful not to scratch the shaft.
5.
Reinsert four bolts (#11) into holes in the end bells of
the motor (don't forget the lifting lugs - #21), making sure the end
bells are seated properly in the ends of the frame.
6.
Install the resolver (#15) according to the orientation
marks and connect cable leads to the block in the junction box
(#31) according to the drawing on page 7.
7.
Reinstall rotor (#17) on the shaft aligning the marks.
8.
Turn the motor by hand to check for rubbing, scraping,
and make sure the shaft turns freely. Check for lengthwise and
sideways movement of the shaft.
9. Torque down all bolts and screws, and proceed to motor
resolver alignment or motor encoder alignment.
© copy right 2012 by P O WE R TEC Industrial Motors, Inc.
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