Richards 137NP, Инструкция по эксплуатации, Страница: 39 / 53

31
c. Replacement of Buffer Washers
The shock of the breaker opening is deadened by two buffer stops, one on either side
of the mechanism assembly. The buffer washer used on these stops are made of a
material which combines the necessary shock-absorbing qualities with long life and
durability, and they should be replaced only by similar washers of the same material
obtained from the factory. These buffer washers are 1/8 inch thick when new. If,
after continued use, the thickness becomes less than 1/16 inch, they should be
replaced with new ones. To replace the buffer washers proceed as follows:
Refer
to Figure 16.
Close the protector and tie the latch, or block crosshead so that it cannot be tripped
accidentally. Remove the cotter pins which hold the buffer pins in place and then
remove the buffer pins. Replace the buffer washers with new ones and reassemble in
the protector. Before putting the cotter pins back, trip the protector and check to see
that the contact supporting frame strikes both buffer pins simultaneously. If not, add
or remove spacer washers under the heads of the buffer pins until it does. The
adjustment is correct when the following conditions exist.
When the breaker open and the contact supporting frame resting on the buffer stops,
the trip resetting plunger should be bearing on the reset cam and holding the
secondary latch in the reset position. When in this position the trip resetting plunger
should be just starting to compress its spring and move relative to the crosshead
frame. In no case should the spring behind the trip-resetting plunger be compressed
solid.
The complete trip mechanism may be removed as a unit by disconnecting the trip coil
leads, and removing the four screws holding the trip mechanism frame to the main
mechanism frame. The trip mechanism may then be lifted and removed completely.
CAUTION: The breaker must be in the “open” position before the trip
mechanism is unbolted from the mechanism.
K. Operating Motor
The operating motor is of the totally enclosed, universal ball-bearing type which requires
minimum maintenance. The motor should be inspected and cleaned periodically to insure
perfect operation. This can best be accomplished by removing the motor from the protector,
removing small hand wheel from the end of motor shaft by loosening the screws, removing
the brushes located on side of motor frame and removing the two studs holding the motor
frames together. This will permit complete dismantling of the motor for reconditioning and
inspection.
The motor is rated for intermittent service, and reasonable care should be exercised when
testing network protectors to avoid overheating of the motor by repeated operation.