GEH-2038 Control and Transfer Switch Type SBM
RATINGS
The switch is rated for a mechanical life of
500,000 operations.
The electrical rating is 600
volts, 20 amperes continuous.
The interrupting
rating depends on several factors; namely, voltage,
current and inductance of the circuit.
It
may be
necessary to use two or more contacts in series
to insure adequate interrupting ability on highly
inductive circuits.
The interrupting ratings are
shown in Table I.
TABLE I
Circuit
Non-Inductive
Inductive Circuit
Number of Contacts
Voltage
1
2(in
1
2(in
24 DC
10.0
30.0
8.0
25.0
48
DC
8.0
25.0
6.0
18.0
125 DC
5.0
15.0
4.0
10.0
250
DC
1.0
3.0
1.0
2.5
600
DC
0.4
0.8
0.3
0.7
115 AC
40.0
75.0
24.0
50.0
230 AC
25.0
50.0
12.0
25.0
460AC
12.0
25.0
5.0
15.0
600AC
10.0
20.0
8.0
12.0
CONSTRUCTION
The Type SBM switch is built up with a series
of stages which are nested into each other, an
operating shaft, a front support and a rear support.
The complete stack is tied together With two
tie bolts threaded into the front support. These tie
bolts also act as a bearing for the cam followers
in each stage. Each stage consists of four stationary
contacts and two moving contacts, (double break
construction) two cams and two cam followers.
The cams are mounted on the operating shaft. In
case only one contact is required in a stage, a
cam follower assembly is omitted.
CONTACT IDENTIFICATION
The contacts are marked for identification
using a standard system. On each side of the switch
............,
midway on the barriers, is a confined marking strip.
These strips are located between the two screws
which define a contact. The marking strip on the
right side, front view, looking toward the rear is
numbered 1, 3, 5, etc. starting at the panel end.
Those on the left side are marked 2, 4, 6, etc.
If
a contact is omitted the terminal screws are also
omitted for that contact.
ENCLOSURES AND MOUNTING
The basic switch is totally enclosed except for
an
opening in the bottom to allow for a visual in
spection of the contacts.
All switches are furnished for mounting in
panels 3/32 to 1/4 inch thick. Variation in panel
thickness is taken up by the use of two saddle
washers mounted between the handle and escutcheon.
INSTALLATION
RECEIVING
Immediately upon receipt of a switch, examine
it for any damage sustained in transit.
If
injury or
rough handling is evident, file a damage claim at
once with the transportation company and promptly
notify the nearest General Electric Apparatus Sales
Office.
The switches are completely assembled
and packed in individual cartons before shipment.
If
the switches are for stock purposes or not
for immediate installation, they should be left in the
shipping carton and stored in a clean dry location.
MOUNTING
For panel mounted switches, holes should be
provided in the panel as shown in Fig. 2.
To mount a switch on a panel, first remove
the handle and escutcheion, including where pro
vided, the position-indicating pointer and the curved
spring washers (saddle spring).
Next, hold the
switch in place on the back of the panel and insert
the mounting screws thz'"ough the escutcheon, panel,
and spacers (if used) into the switch front support,
but do not tighten the mounting screws. Attach the
pointer, saddle springs and handle.
Align the
escutcheon on the panel.
When mounting removable-handle switches be
certain that the shaft of the switch is properly
positioned, so the handle is easily removed before
the mounting screws are tightened.
MAINTENANCE
SERVICING
CONT ACT CLEANING
At regular intervals, the switch contacts should
be inspected for wear and burning. An opening at
the bottom of the switch has been provided for this.
(See Fig. 3)
If
the contacts are slightly pitted or
4
coated with sulphide, they should be cleaned with
a flexible burnishing tool similar to that included
in the XRT relay tool kit.
REPAffi AND REPLACEMENT
In some cases, it is desirable to either replace
a contact stage or to add an additional amount of
contacts.
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