Siemens RL Series, Instructions Manual

Page: 37 / 76

Maintenance
Contact Replacement (See Figure 9)
The contact structure
consists of main current carrying contacts and arcing contacts
arranged so that initial contact make and final contact break is
by means of the arcing contacts. The actual contact surfaces
are clad with an alloy facing which greatly reduces mechanical
wear and arc erosion,
When inspection of the alloy facing indicates that the contacts
should be replaced, it should be noted that hinge contact
fingers (53, 55), main contact fingers (46) , and arcing contacts
(61 ) are spring loaded. Therefore , care must be used in
removal and installation of any of the contacts.
M a i n Contact Fin gers (See Figure 9)
With the circuit breaker contacts open and the stored energy springs
discharged, the main contact fingers ( 46) may be removed by
loosening screws (44, 45) enough to relieve the compression on
springs (47, 48). There are two springs behind each finger. It is
important that they be positioned properly upon reinstallation. If
difficulty is experienced in correctly positioning these springs, the
upper and lower primary disconnects ( 1 68
Figure 18),
may be
removed from each phase and the circuit breaker tipped to rest on
the ends of the Sideplates (2) and (3). After the contact fingers are
replaced, connector (37) should be positioned in the center of the
slot in the molded base to assure correct alignment of the primary
disconnect fingers.
Stationary Arcing Contact (See Figure 9)
The stationary arcing contact is a part of a connector (37) and may
be replaced by proceeding as above. In this case, screws ( 44, 45)
must be removed. However, to provide clearance for removal of
connector the backpanel (33) may have to be loosened by removing
screws (5S, 59 and 23,
Figure
I
7).
By
removing pin (98 and 99
Figure
1 8), the entire assembly can be lifted out.
Hinge Contact Fingers (See Figure 9)
H inge contact fingers (53, 55) may be removed as follows:
Remove backpanel. Remove lower connector (49) and moving
contacts by removing screws (59). On all
RL
Breakers springs ( 54,
56) are unloaded by rotating the moving contacts toward a horizontal
position relative to the stationary contact (49). Remove screws (70)
to remove moving contacts. Slide fingers
(53, 55)
sideways to
remove. Replace fingers by compressing spring ( 56, 54) in position
and inserting the fingers from the side. Holding connector (49) in a
vise, and using a tool such as 1 8 -657-143-2 79 aids the operation.
Movable Arcing and Main Contact (See Figure 9)
Either movable arcing contact ( 6 1 ), or main contact (62), or both,
may
be removed and replaced as fol lows:
IMPORTANT: Extreme care should be taken to hold the assembly
firmly to retain spring seat (83, 84) and spring (8 1, 82) upon removal of
the screws (78).
1 7
Remove
lower
connectors and moving contacts
a�
described in the
preced ing
sec
t i on
.
The complete movable contact assembly may
now be brought to the bench. The location of spacers should be
noted.
Loosen
n
u
t
s
( 80)
and remove
screws
(78)
from pin (7 1 ),
alternate
several
turns each side to prevent binding. (The reverse
procedure is followed for reinstallation.)
The movable
arcing
contacts or main contacts may now be replaced.
Compress spring (8 1 , 82)
to
engage screws (78). Care should
be taken to replace spacers correctly. Check alignment and
adjustment
or contacts upon reassembly.
Tripping Actuator Operation and Replacement
When the overcurrent trip device senses a circuit condition
that
r
e q u i res the circuit breaker to open, it produces an output
that is f e d to the tripping actuator. This device then causes the
circuit breaker contacts to open and isolate the circuit
Mounted on the circuit breaker, the tripping actuator is held in
a charged position by a permanent magnet. When the
overcurrent trip device issues a trip signal, the coil of the
tripping actuator is energized, which causes the magnetic flux
to s h i
ft
to
a
new path, releasing the stored energy of a spring
l o c ated inside the tripping actuator. The spring provides the
energy to trip the breaker, moving the trip-flap clear of the
toggle l a t c h
.
If the spri ng-loaded armature does not reset during trip
operation, spacer washers may be added to obtain positive
re set of the a rmature .
I
f adding spacers does not cause the
armature to be
r
es et
,
the tripping actuator should be replaced
(i f breaker mechanism is not at fault).
Note: Do not a
t
tem pt to disassemble the tripping actuator as
this may destroy the magnetic field set up by the permanent
magnet and will render the actuator latch inoperative until
magnetized
When replacing
a tripping actuator, the coil leads must be
c o nn ected to the terminal block of the trip device in the correct
po
l
a
ri
t
y relationship.
The black lead of the coil must be connected to terminal 6, the
red lead of the coil connected to terminal 7, and the blue lead
of the c o
i
l
to terminal 8 of the static trip
device.
Static
Trip
I l l Overcurrent Devices
When the Static Trip device or tripping actuator has been
re p l a ced
,
the circuit breaker should be tested to ensure proper
operation of
all
components. Refer to 'Static Trip Ill
I nf ormation and I nstruction Guide', SG-31 1 8 , and 'Portable
Te st Set I nstructions', S G-31 38, for the information on testing
the static tripping system on a circuit breaker.
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